Estudo exploratório da Síndrome Hipoplasia Cartilagem-Cabelo no Brasil: uma abordagem genômica, proteômica e de análise estrutural de RNA / Exploratory study of Hypoplastic Cartilage-Hair Syndrome in Brazil: a genomic, proteomic and RNA structural analysis approach

A Hipoplasia Cartilagem-Cabelo (do inglês, Cartilage Hair Hypoplasia; CHH) é uma doença autossômica recessiva descrita por McKusick et al., em 1964 em crianças da comunidade Amish. Clinicamente, os pacientes apresentam displasia óssea metafisária em diferentes graus de gravidade. Além disso, também pode ser observado hipotricose e imunodeficiência. Já no âmbito molecular, a condição se caracteriza por variantes patogênicas do gene RMRP. Apesar de ter sido delineada há quase 60 anos, ainda não existe uma correlação genótipo-fenótipo bem compreendida. Este trabalho é uma continuação do trabalho de mestrado realizado no IFF/Fiocruz, durante 2017 e 2018, no qual foi descrita uma coorte de 23 pacientes brasileiros com CHH em que foram encontradas diversas variantes patogênicas. Dentre estas, a variante g.196C>T destacou-se por sua elevada frequência no grupo estudado, diferentemente do observado em pacientes de outras nacionalidades, sugerindo um possível efeito fundador (EF) para a população brasileira. Esse trabalho teve por objetivo realizar diferentes ensaios moleculares para auxiliar na compreensão da CHH, além de investigar a hipótese de uma origem ancestral comum da variante g.196C>T. O estudo foi dividido em 4 eixos, sendo três relacionados às pesquisas de caráter exploratório dos mecanismos da doença e um dedicado à análise do EF. Dentro deste último, utilizando um painel de marcadores do tipo TAG SNPs cuidadosamente selecionados, foi observado que cromossomos de diferentes regiões brasileiras carregando o nucleotídeo T na posição196 do gene RMRP compartilharam o haplótipo T/C/G/A (16/17 haplótipos), apontando para uma origem comum desta substituição de base no gene RMRP. Adicionalmente, foram realizadas análises de proteômica comparativa, evidenciando que o perfil proteômico dos leucócitos de pacientes e controles expressam proteínas que traduzem vias moleculares distintas, além de apresentar diferenças de expressão de proteínas importantes relacionadas aos fenótipos clínicos da doença. Também foram realizados ensaios de RT-qPCR que mostraram que tanto os níveis do RNA RMRP, quanto dos dois pequenos RNAs derivados de RMRP, estavam significativamente reduzidos nos pacientes em relação ao grupo controle. Por fim, com o intuito de tentar prever o impacto das variantes na estrutura tridimensional do RNA, foi realizada uma análise in silico que mostrou que as alterações patogênicas identificadas nos pacientes ocorreram tanto em regiões conservadas entre espécies de mamíferos quanto em domínios essenciais para o complexo ribonucleoproteico. Duas alterações estão localizadas em regiões associadas à biogênese dos pequenos RNAs derivados de RMRP. Além disso, foi possível observar que certas variantes podem alterar o pareamento de bases e a topologia da estrutura das alças da molécula, o que poderia influenciar na montagem do complexo RNAse MRP. Em conjunto, os dados desta tese lançam luz sobre diversos pontos ainda não explorados para CHH, além de dar suporte para novos estudos que tenham por objetivo viabilizar uma medicina de precisão, contribuindo para minimizar os impactos da doença e para a promoção da qualidade de vida dos pacientes.

Cartilage Hair Hypoplasia (CHH) is an autosomal recessive disease described by McKusick et al. in 1964 in the Amish community. Clinically, patients present metaphyseal bone dysplasia in different degrees of severity. In addition, hypotrichosis and immunodeficiency may also be present. At the molecular level, the condition is characterized by pathogenic variants of the RMRP gene. Although CHH has been described more than 60 years ago, the genotype-phenotype correlation is still not well-understood. This work is a continuation of the dissertation carried out at IFF/Fiocruz, during 2017 and 2018, in which a cohort of 23 Brazilian patients with CHH was described and several pathogenic variants were found. Among these, the high frequency of g.196C>T variant in the studied group called our attention, unlike that observed in patients of other nationalities, suggesting a possible founder effect (EF) in the Brazilian population. This work aimed to perform different molecular assays to aid in the understanding of CHH, in addition to investigating the hypothesis of a common ancestral origin of the g.196C>T variant. The study was divided into 4 axes, three related to exploratory research on disease mechanisms and one dedicated to the analysis of EF. Within the latter, using a carefully selected panel of TAG SNPs markers, it was observed that chromosomes from different Brazilian regions carrying T at nucleotide 196 of the RMRP gene shared the T/C/G/A haplotype (16/17 haplotypes), indicating a common origin of this base substitution at position 196 of the RMRP gene. Additionally, comparative proteomics analysis was performed, showing that the proteomic profile of leukocytes from patients and controls express proteins that translate distinct molecular pathways, in addition to presenting differences in the expression of proteins related to important clinical phenotypes of the disease. RT-qPCR assays were also performed, which showed that both RMRP RNA levels and the two RMRP-derived small RNAs were significantly reduced in patients compared to the control group. Finally, in order to try to predict the impact of the variants on the three-dimensional structure of the RNA, an in silico analysis was performed which showed that the pathogenic alterations identified in the patients occurred both in regions conserved between mammalian species and in domains essential for the ribonucleoprotein complex. Two alterations are located in regions associated with the biogenesis of RMRP-derived small RNAs. In addition, it was possible to observe that certain variants can change the base pairing and the topology of the structure of the molecule's loops, which could influence the assembly of the RNAse MRP complex. Together, the data from this thesis shed light on several points not yet explored for CHH, in addition to providing support for new studies that aim to enable a precision medicine toward CHH patients, helping to minimize the impacts of the disease and to promote quality of life of patients.

La endogamia como causa de consanguinidad y su asociación con anomalías congénitas / Endogamy as a cause of consanguinity and its association with congenital anomalies

El papel de la endogamia como causa de homocigosidad en la salud humana es un foco de interés en genética médica, debido a su relación con anomalías congénitas y patologías genéticas recesivas. Es un tema importante a pesar de que las tasas de uniones consanguíneas en ciertas sociedades han disminuido con el tiempo; sin embargo, en algunas comunidades se han mantenido estables o han aumentado. La consanguinidad es practicada hasta en el 10% de la población mundial, y los motivos más comúnmente citados son socioculturales y socioeconómicos. Aunque se ha visto una disminución de esta práctica, probablemente por la migración urbana y el aumento de las tasas de educación, la consanguinidad continúa practicándose en todo el mundo. Los efectos más significativos sobre los resultados reproductivos se deben, principalmente, a condiciones hereditarias autosómicas recesivas, que también aumentan la frecuencia de algunos desórdenes médicos. El objetivo de esta revisión es dar a conocer la epidemiología y los factores predisponentes de la consanguinidad, así como presentar la evidencia actual de la asociación entre la consanguinidad originada en la endogamia y las anormalidades congénitas y patologías médicas como consecuencia de trastornos genéticos mendelianos. Se requiere un enfoque culturalmente apropiado para el asesoramiento genético en relación con la endogamia

The role of consanguinity as a cause of homozygosity in human health is a focus of interest in medical genetics, due to its relationship with congenital anomalies and recessive genetic pathologies. This is an important issue since the rates of consanguineous unions in certain societies have decreased over time, but have remained stable or have increased in others. Consanguinity is practiced in up to 10% of the world population, and the most common reasons are sociocultural and socioeconomic factors. Although there has been a decrease in this practice, probably due to urban migration and an increase in education rates, consanguinity continues to be practiced throughout the world. The most significant effects on reproductive outcomes are mainly due to autosomal recessive hereditary conditions, that also increase the frequency of medical disorders. The aim of this review is to present the current evidence of the association between consanguinity originating from endogamy, with congenital abnormalities and medical disorders originated from mendelian genetic pathologies. A cultural appropriate approach is required for genetic counseling in relation to consanguineous endogamy

Decifrando o "mistério dos gêmeos": vinte anos de pesquisa em Cândido Godói, Rio Grande do Sul / Solving the "twins mystery": twenty years of research in Cândido Godói, Rio Grande do Sul state

Cândido Godói (CG) é um pequeno município brasileiro localizado no noroeste do Rio Grande do Sul e é conhecido como "Cidade dos Gêmeos" devido à alta taxa de nascimentos gemelares na região. Diante de um fato tão notável, muitas explicações foram sugeridas. Entre estas teorias, a que mais recebeu atenção da mídia, mesmo sem base científica, foi a de que a gemelaridade seria fruto de experimentos de um médico nazista alemão foragido após a Segunda Guerra Mundial. A convite da própria comunidade de CG, nosso grupo de pesquisa trabalha para resolver este mistério desde 1994, analisando diferentes fatores possivelmente relacionados, em especial suas características genéticas. Aqui, nós sumarizamos os principais resultados obtidos em mais de duas décadas de pesquisa, com foco nas particularidades do processo de comunicação dos resultados, aspectos éticos e como os achados científicos naquela comunidade contribuem não apenas com a resolução de um mistério histórico e local, mas também com o estudo de outras questões, como a reprodução humana e as bases biológicas da gemelaridade. (AU)

Cândido Godói (CG) is a small town located in the northwest region of Rio Grande do Sul state which is known as "Town of Twins" because of the high rate of twin births. Many explanations have been suggested for such a noteworthy fact. The theory that has received most attention from the press, despite a lack of scientific evidence, was that twinning would result from experiments conducted by a Nazi German physician who had been a fugitive after World War II. Invited by the local community, our research team has been dedicated to solving this mystery since 1994 by analyzing different possibly related factors, especially genetic characteristics. In this paper, we summarize the main results obtained in more than two decades of research, focusing on the particular communication process of the results, ethical aspects, and how the scientific findings in that community have contributed not only to the resolution of a historical and localized mystery, but also with the study of other issues such as human reproduction and biological basis of the twinning process. (AU)

A Unique Mutational Spectrum of MLC1 in Korean Patients With Megalencephalic Leukoencephalopathy With Subcortical Cysts: p.Ala275Asp Founder Mutation and Maternal Uniparental Disomy of Chromosome 22

BACKGROUND: Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare inherited disorder characterized by infantile-onset macrocephaly, slow neurologic deterioration, and seizures. Mutations in the causative gene, MLC1, are found in approximately 75% of patients and are inherited in an autosomal recessive manner. We analyzed MLC1 mutations in five unrelated Korean patients with MLC. METHODS: Direct Sanger sequencing was used to identify MLC1 mutations. A founder effect of the p.Ala275Asp variant was demonstrated by haplotype analysis using single-nucleotide polymorphic (SNP) markers. Multiple ligation-dependent probe amplification (MLPA) and comparative genomic hybridization plus SNP array were used to detect exonic deletions or uniparental disomy (UPD). RESULTS: The most prevalent pathogenic variant was c.824C>A (p.Ala275Asp) found in 7/10 (70%) alleles. Two pathogenic frameshift variants were found: c.135delC (p.Cys46Alafs*12) and c.337_353delinsG (p.Ile113Glyfs*4). Haplotype analysis suggested that the Korean patients with MLC harbored a founder mutation in p.Ala275Asp. The p.(Ile113Glyfs*4) was identified in a homozygous state, and a family study revealed that only the mother was heterozygous for this variant. Further analysis of MLPA and SNP arrays for this patient demonstrated loss of heterozygosity of chromosome 22 without any deletion, indicating UPD. The maternal origin of both chromosomes 22 was demonstrated by haplotype analysis. CONCLUSIONS: This study is the first to describe the mutational spectrum of Korean patients with MLC, demonstrating a founder effect of the p.Ala275Asp variant. This study also broadens our understanding of the mutational spectrum of MLC1 by demonstrating a homozygous p.(Ile113Glyfs*4) variant resulting from UPD of chromosome 22.

Mutación fundadora en síndrome de Lynch tipo II / Founder mutation in Lynch syndrome

El síndrome de Lynch es la más frecuente de las neoplasias colorrectales hereditarias. Se origina por mutaciones germinales deletéreas familia-específicas en los genes que codifican proteínas de reparación del ADN: MLH1 (homólogo humano de mutL), MSH2 y MSH6 (homólogo humano de mutS 2 y 6, respectivamente), PMS2 (homólogo humano de PMS1 2) y MUTYH (homólogo humano de la ADN-glycosilasa mutY). La mutación c.2252_2253delAA, p.Lys751Serfs*3 en el exón 19 del gen MLH1 segrega con un haplotipo descripto en la región norte de Italia y cuyo origen fue atribuido a un efecto fundador. Esta mutación co-segrega con características típicas del síndrome de Lynch, incluyendo afectación temprana y múltiples tumores primarios en el mismo individuo, una alta frecuencia de cáncer pancreático, elevada inestabilidad microsatelital y falta de expresión de PMS2. En el presente trabajo se comunica dicha mutación en una paciente argentina con adenocarcinoma endometroide de útero en cuya historia familiar existen antecedentes de cáncer de colon diagnosticado antes de los 50 años en familiares de primer grado, reuniendo los criterios de Ámsterdam I y síndrome de Lynch II. Los polimorfismos presentes en la paciente coinciden con el haplotipo descripto en una región del norte de Italia. El alto grado de patogenicidad asociada a esta mutación hace imprescindible el estudio de todos los integrantes de las familias con cáncer hereditario permitiendo el diagnóstico genético pre-sintomático, la instauración de tratamientos o conductas preventivas y su seguimiento.

Lynch syndrome is the most frequent syndrome in hereditary colorectal cancer, a family-specific deleterious mutations in genes encoding DNA reparation proteins: MLH1 (mutL homolog 1), MSH2, MSH6 (mutS homolog 2 y 6, respectively), PMS2 (PMS1 homolog 2, mismatch repair system component) y MUTYH (mutY DNA glycosylase).The c.2252_2253delAA, p.Lys751Serfs*3 mutation in MLH1 gene segregates with a haplotype reported in the northern region of Italy and whose origin was attributed to a founder effect. This mutation co-segregates with typical characteristics of Lynch syndrome, including early age at onset and multiple primary tumors in the same individual, a high frequency of pancreatic cancer, high microsatellite instability and lack of PMS2 expression. This report describes a mutation in an Argentinian patient with endometrioid adenocarcinoma of uterus. Her first-degree relatives had a history of colon cancer diagnosed before 50 years, fulfilling the Amsterdam Criteria I and Lynch syndrome II. The high pathogenicity associated to this mutation makes necessary the study of all members from families with hereditary cancer, allowing pre-symptomatic genetic diagnosis, early assessment and the instauration of preventive treatments.

Clinical profile and mutation analysis of xeroderma pigmentosum in Indian patients.

Background: Xeroderma pigmentosum (XP) is an autosomal recessive genetic disorder characterized by cutaneous and ocular photosensitivity and an increased risk of developing cutaneous neoplasms. Progressive neurological abnormalities develop in a quarter of XP patients. Aim: To study the clinical profile and perform a mutation analysis in Indian patients with xeroderma pigmentosum. Methods: Ten families with 13 patients with XP were referred to our clinic over 2 years. The genes XPA, XPB and XPC were sequentially analyzed till a pathogenic mutation was identified. Results: Homozygous mutations in the XPA gene were seen in patients with moderate to severe mental retardation (6/10 families) but not in those without neurological features. Two unrelated families with a common family name and belonging to the same community from Maharashtra were found to have an identical mutation in the XPA gene, namely c.335_338delTTATinsCATAAGAAA (p.F112SfsX2). Testing of the XPC gene in two families with four affected children led to the identification of the novel mutations c.1243C>T or p.R415X and c.1677C>A or p.Y559X. In two families, mutations could not be identified in XPA, XPB and XPC genes. Limitation: The sample size is small. Conclusion: Indian patients who have neurological abnormalities associated with XP should be screened for mutations in the XPA gene.

A Costa Rican family affected with Charcot-Marie-Tooth disease due to the myelin protein zero (MPZ) p.Thr124Met mutation shares the Belgian haplotype / Una familia costarricense afectada por la enfermedad de Charcot-Marie-Tooth, debido a la mutación p.thr124Met en la proteína mielina cero (MPZ) compartida con el haplotipo belga

The p.Thr124Met mutation in the myelin protein zero (MPZ) causes the Charcot-Marie-Tooth disease type 2J, a peripheral neuropathy with additional symptoms as pupillary alterations and deafness. It was observed in several families around the world originating e. g. from Germany, Belgium, Japan, Italy and North America. Here we report Central American patients originating from a family in Costa Rica carrying this mutation. Clinical, electrophysiological and molecular analysis of patients and controls were performed, including gene and linked markers´ sequencing. Carriers share almost the entire haplotype with two non related Belgian CMT patients. As a result of the haplotype analysis, based on ten markers (seven SNPs, two microsatellites and an intronic polyA stretch), the founder effect hypothesis for this allele migration is suggestive. Rev. Biol. Trop. 62 (4): 1285-1293. Epub 2014 December 01.

La mutación p.thr124Met en la proteína mielina cero (MPZ) causa la enfermedad de Charcot-Marie-Tooth tipo 2J, una neuropatía periférica con síntomas adicionales como alteraciones pupilares y sordera. Se ha observado en varias familias alrededor del mundo, originarias de Alemania, Bélgica, Japón, Italia y Norteamérica, entre otras. Aquí reportamos a pacientes centroamericanos provenientes de Costa Rica que acarrean esta mutación. Se realizaron análisis clínico, electrofisiológico y molecular de pacientes y controles, incluyendo secuenciación del gen y de marcadores ligados a éste. Estos pacientes comparten casi por completo el haplotipo con dos pacientes belgas no emparentados. Como resultado del análisis de los haplotipos, basado en diez marcadores (siete SNPs, dos microsatélites y un elemento poli-A intrónico), se sugiere que se ha dado un efecto fundador en la migración de este alelo.

Predisposición genética para el cáncer de mama: genes BRCA1 y BRCA2 / Genetic predisposition for breast cancer: BRCA1 and BRCA2 genes

El descubrimiento de los genes BRCA1 y BRCA2 ha llevado a la introducción de pruebas genéticas cada vez más sofisticadas para medir el riesgo de cáncer de mama de origen hereditario, entre otras cosas. En el presente artículo exploramos los criterios a seguir para realizar pruebas para estos genes, así como las implicaciones en el tratamiento para los pacientes en caso de identificarlos.

The discovery of genes BRCA1 and BRCA2 has led to the introduction of genetic tests more complex every time for the evaluation ofthehereditarycancerrisk,amongothers.In the present paper we explore the criteria to decide when to run the testing for the genes, as well as the implications for the treatment of patients who are identified with them.

Population analysis of the GLB1 gene in South Brazil

Infantile GM1 gangliosidosis is caused by the absence or reduction of lysosomal beta-galactosidase activity. Studies conducted in Brazil have indicated that it is one of the most frequent lysosomal storage disorders in the southern part of the country. To assess the incidence of this disorder, 390 blood donors were tested for the presence of two common mutations (1622-1627insG and R59H) in the GLB1 gene. Another group, consisting of 26 GM1 patients, and the blood donors were tested for the presence of two polymorphisms (R521C and S532G), in an attempt to elucidate whether there is a founder effect. The frequencies of the R59H and 1622-1627insG mutations among the GM1 patients studied were 19.2 percent and 38.5 percent, respectively. The frequency of polymorphism S532G was 16.7 percent, whereas R521C was not found in the patients. The overall frequency of either R59H or 1622-1627insG was 57.7 percent of the disease-causing alleles. This epidemiological study suggested a carrier frequency of 1:58. Seven different haplotypes were found. The 1622-1627insG mutation was not found to be linked to any polymorphism, whereas linkage disequilibrium was found for haplotype 2 (R59H, S532G) (p < 0.001). These data confirm the high incidence of GM1 gangliosidosis and the high frequency of two common mutations in southern Brazil.

Mutación fundadora en una familia argentina con cáncer colorrectal hereditario / Detection of a founder mutation in an Argentine family with hereditary non polyposis colorectal cancer

El cáncer colorrectal hereditario no poliposo (CCHNP) se relaciona con mutaciones en los genes reparadores de ADN (MLH1, MSH2 y MSH6). La mayoría de estas alteraciones son familia-específicas y su detección suele requerir la secuenciación completa de los genes relacionados. Se detectó una mutación puntual (2269-2270insT) en el último codón del gen MLH1 en familias de un área del norte de Italia (Reggio Emilia) y su origen se considera debido a un efecto fundador. En este trabajo presentamos una familia mendocina con CCHNP portadora de la misma mutación, cuyos ancestros eran oriundos de Reggio Emilia. Para la detección de la mutación se diseñó una estrategia basada en PCR y posterior corte enzimático. La mutación fue hallada en tres integrantes de la familia estudiada, dos de los cuales no presentaban sintomatología clínica. Estos pacientes fueron seguidos preventivamente mediante colonoscopias. La metodología utilizada en nuestro laboratorio fue específica y sensible para la detección de una mutación previamente registrada y permitió realizar el diagnóstico genético molecular en el país, evitando el envío de muestras al extranjero. Es de importancia destacar que el diagnóstico genético pre-sintomático de cáncer hereditario, enfocado desde un grupo multidisciplinario de profesionales, permite un mejor seguimiento y apoyo a las familias afectadas.

Hereditary non polyposis colorectal cancer (HNPCC) has been related to mutations in the DNA mismatch repair genes (MLH1, MSH2 y MSH6). Mutation detection analysis requires the complete sequencing of these genes, given the high frequency of family-specific alterations. A point mutation (2269- 2270insT) in the last codon of the MLH1 gene has been detected in families from a northern region of Italy (Reggio Emilia).Given that this alteration was registered only in people from this region, it has been considered a founder mutation. In this work, we present an Argentine HNPCC family whose ancestors were natives from the Reggio Emilia, Italy, and who were carriers for this mutation. In order to detect the genetic alteration, a PCR was developed followed by a restriction enzyme incubation assay. The mutation was detected in 3 family members, two of them without clinical symptoms. The PCR/restriction enzyme methodology has been sensitive and specific for the detection of this mutation. It has allowed the performance of a pre-symptomatic genetic diagnosis in the Argentine HNPCC family, avoiding sending samples abroad. It is worth mentioning that pre-symptomatic diagnosis of hereditary cancers allows enhanced surveillance and support for the affected families when it is performed by a multidisciplinary group.

Founder effect of two families with TGFBI related Thiel-Behnke corneal dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the transforming growth factor beta induced (TGFBI; BIGH3) gene mutation and founder effect of two large Chinese families clinically diagnosed as Thiel-Behnke corneal dystrophy.</p><p><b>METHODS</b>Fifteen members including 13 affected and 2 healthy in family A, 14 members including 6 affected and 8 healthy in family B, as well as 20 other unrelated healthy individuals were tested for TGFBI gene mutation. Haplotype analysis and clinical examination were also carried out in the two families.</p><p><b>RESULTS</b>In exon 12 of the TGFBI gene, 1664G to A change was detected in all the patients, which leads to an amino acid replacement of arginine with glutamine (p.Arg555Gln). Members of the two families share some similar haplotypes.</p><p><b>CONCLUSION</b>Genetic analysis is helpful in the diagnosis of corneal dystrophy. The two families may come from a same ancestor.</p>

Sequence Variations and Haplotypes of the GJB2 Gene Revealed by Resequencing of 192 Chromosomes from the General Population in Korea

OBJECTIVES: Hearing impairment (HI) is the most common sensory deficit in human. The Gap Junction Protein, Beta-2 (GJB2) gene encodes the protein connexin 26, and this gene accounts for up to half of the cases of autosomal recessive nonsyndromic HI. This study was conducted to obtain a set of sequence variations (SVs) of the GJB2 gene among Koreans from the general population for making molecular genetic diagnoses and performing genetic counseling. METHODS: We resequenced the GJB2 gene in 192 chromosomes from 96 adult individuals of Korean descent and who were without a history of hearing difficulty. The data of the SVs was obtained and the haplotypes were reconstructed from the data. RESULTS: Five SVs were observed, including a novel one (c.558G>A; p.T186T), with the allele frequencies ranging from 0.5% (1/192) to 41% (79/192). The linkage disequilibrium study and haplotype construction showed that some of the SVs are in tight linkage, resulting in a limited number of haplotypes. CONCLUSION: We observed SVs of the GJB2 gene with different allele frequencies, and a limited number of haplotypes were constructed. The data from this study can be used as reference data for GJB2-related hearing genetic studies, including studies on the founder effect and population genetics, and this data is particularly relevant to people of East Asian decent.

Haplotype analysis and possible founder effect at the R778L mutation of the ATP7B gene in Korean patients with Wilson's disease / 대한간학회지

BACKGROUND/AIMS: Wilson's disease (WD) is an inherited disorder of copper metabolism caused by alteration of the P-type adenosine triphosphatase (ATP) 7B gene. In this study, we analyzed the frequency of well-known mutations and constructed the first haplotypes for Koreans. In addition, we evaluated whether a founder effect existed in Korean patients with WD. METHODS: We obtained DNA samples from 21 patients with WD and their parents (total cohort n=63). ATP7B gene mutations were identified by direct sequencing methods, and microsatellite typing was performed at D13S315, D13S1325, and D13S316 with fluorescent dye-labeled primers. Any founder effect was identified by using 42 normal alleles from parents with a normal phenotype as a control group. The chi-square test and Fisher's exact test were used for statistical analysis. RESULTS: Three common mutations were found in 23 chromosomes obtained from 21 patients: the R778L mutation at exon 8 (15/23, 65.2%), the A874V mutation at exon 11 (6/23, 26.1%), and the N1270S mutation at exon 18 (2/23, 8.7%). D13S315 and D13S316 showed linkage disequilibrium at alleles 5 and 4, respectively, in patients with the R778L mutation (P=0.0157 and 0.0001, respectively). The haplotype made up of these two alleles occurred significantly more frequently in patients with the R778L mutation (5-R778L-4, D13S315-mutation-D13S316) than in the controls (P=0.0018). CONCLUSIONS: The arche haplotype of the ATP7B gene in Korean patients with WD may be 5-R778L-4 (D13S315.mutation.D13S316), and it might illustrate a founder effect.

Alta prevalencia de trastorno específico de lenguaje en isla Robinson Crusoe y probable efecto fundador / High prevalence of specific language impairment in Robinson Crusoe Island. A possible founder effect

Specific language impairment (SLI) occurs in 2 percent to 8 percent of preschool children. Major and candidate genes are probably involved. Genetic drift is a cause for the presence of high frequencies of deleterious alíeles of a specific disease and the founder effect is one of its forms. Robinson Crusoe Island has 633 inhabitants and its actual population began with 8 families that repopulated the island at the end ofXIXth century. Aim To assess the frequency of specific language impairment among children living in Robinson Crusoe Island. Material and methods: All 66 children aged between 3 and 9 years living in the island, were studied. Parents were interviewed and in children, non verbal intelligence, audiometric parameters, comprehension and expression of oral language were assessed. Extended genealogies were also performed. Results: Forty children had at least one parent that was descending of founder families. Among these, 35 percent had SLI. Eighth five percent of SLI affected children came from the same colonizer family. Conclusions: The prevalence of SLI in Robinson Crusoe Island is higher than that reponed in mainland Chile and abroad. This high prevalence, associated to a high frequency of consanguinity, supports the influence of genetic mechanisms in SLI transmission, based on a founder effect.

Molecular diagnosis of 5alpha-reductase-2 gene mutation in two Indian families with male pseudohermaphroditism / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To identify the genotype of two Indians with male pseudohermaphroditism.</p><p><b>METHODS</b>Standard radioimmunoassay procedure was used for estimating hormonal levels. Conventional cytogenetic analysis was carried out for diagnosing the genetic sex in these subjects with genital ambiguity. Molecular analysis was carried out by standard polymerase chain reaction procedure using different sets of primers and reaction conditions specific for the 5alpha-reductase type 2 gene (SRD5A2) gene. Direct sequencing was carried out using the ABI Prism dye terminator sequencing kit and the ABI 310 sequencing apparatus.</p><p><b>RESULTS</b>We found an SRD5A2 gene mutation in exon 5, where arginine is substituted with glutamine (R246Q), in two males with pseudohermaphroditism and ambiguous genitalia from unrelated families. This is the first time this mutation has been reported in individuals from India.</p><p><b>CONCLUSION</b>Identification of the R246Q mutation of the SRD5A2 gene from two unrelated Indian families possibly extends the founder gene effect.</p>

Hereditary Breast Cancer in Korea: A Review of the Literature / 한국유방암학회지

Hereditary breast carcinomas associated with BRCA1/2 mutations have unique clinicopathological and epidemiological characteristics. The objective of this study is to outline the prevalence, founder effect and clinicopathological characteristics of BRCA1/2 mutations for hereditary breast cancers from an analysis of reports recently published regarding Korean subjects. The prevalence of BRCA1 and/or BRCA2 mutations is 2.5-3.1% for sporadic breast cancers, 19.4-42.9% for familiar breast cancer patients with two or more affected first- and second- degree relatives with breast or ovarian cancers and 9.6-18.3% for early breast cancers. Common mutations for the Korean subjects were 2552delC, 3476insA, 4184del4, 5589del8, and 5615del111insA for BRCA1; and 7708C>T for BRCA2. These mutations were not found in Ashkenazi Jewish or Icelandic subjects. The proportion of estrogen or progesterone receptor (ER/PR) or ER/PR/HER2 triple negative status, basal-like phenotype as detected by immunohistochemical staining, and undifferentiated histological grade in Korean BRCA mutation subjects were higher than in subjects lacking BRCA1/2 mutations. Our review found that previous studies describing BRCA mutations among Korean subjects were limited. Since the clinicopathological, phenotypic and epidemiological characteristics of the BRCA1/2 mutations among Korean subjects are different from those among subjects from the Americas and Europe, more studies of hereditary or familial breast cancer including BRCA mutations must be conducted. A largescale prospective study called Korean Hereditary Breast Cancer Study (KOHBRA) was started from May 2007, and future information provided by the KOHBRA study will make a substantial contribution to solving the basic questions in etiology, individual susceptibility and clinicopathological characteristics for hereditary breast cancer among Korean subjects.

Pedigree analyses in the Breeding Program for Nellore Cattle

Parameters based on the probability of gene origin were used to describe genetic variability in three reproductive groups from the Breeding Program for Nellore Cattle (PMGRN). The three reproductive populations (cows in reproductive age, bulls from artificial insemination centers and young bulls in progeny test) generated medium to low values. The effective number of founders (Nf ), the effective number of ancestors (Na) and the remaining genomes (Ng) suggest low founder representativeness, high genetic contribution by some ancestors, considerable loss of founder alleles and lack of allelic representativeness in bulls kept in artificial insemination centers and young sires in progeny test in relation to the diversity on the farms participating in the PMGRN. The parameters based on the probability of gene origin in the three reproductive groups were: 84.3, 53 and 54.2 (Nf ); 71, 36.6 and 30 (Na) and 51.4, 19.3 and 19 (Ng) for cows, bulls from artificial insemination centers and young sires in progeny test, respectively. Future matings and the introduction of selected progeny reproduction may decrease the parameters based on the probability of gene origin in each reproductive group, thereby increasing considerably the additive relationship in the three reproductive groups and consequently increasing the probability of inbreeding in the future. Strategies to maintain genetic variability in bull populations must be implemented.

Análisis de isonimia entre poblaciones del noroeste de Colombia / Isonymy analysis between 2 populations in northwestern Colombia

Introducción. La utilización de la frecuencia de apellidos como marcadores de linajes paternos ha permitido caracterizar poblaciones. Los principios de isonimia se han empleado para determinar el grado de estructuración genética, las tasas de migraciones y las relaciones de ancestría y origen entre poblaciones. Este análisis se aplicó a dos poblaciones históricamente relacionadas y consideradas como aislados genéticos. Objetivo. Evaluar las relaciones genéticas y de origen entre Aranzazu y Marinilla y su zona de influencia por medio de análisis de frecuencia de apellidos. Materiales y métodos. A partir de la base de datos del Sistema de Identificación de Beneficiarios de los Programas Sociales, Sisbén, se calcularon los parámetros poblacionales de coeficiente de parentesco (ii), la homogeneidad poblacional con los estimadores B (porcentaje de la población que comparte los siete apellidos más frecuentes) y C (15 apellidos más frecuentes) y la distancia genética de Cavalli-Sforza en tres poblaciones del núcleo fundador de Marinilla y Rionegro como población externa. Resultados. Marinilla y Aranzazu, al igual que las poblaciones de Marinilla y su zona de influencia, mostraron los mayores valores de homogeneidad (valores B entre 0,25 y 0,5) comparados con Rionegro (B = 0,159) y también mayores valores de parentesco intrapoblacional (valores ii entre 0,0034 y 0,01). Las menores distancias se encontraron entre Marinilla y Aranzazu.Conclusiones. Aranzazu es una población con características similares a las de Marinilla y su zona de influencia y debido al efecto fundador, estas poblaciones pueden presentar características genéticas similares. Por lo tanto, las enfermedades genéticas, principalmente las de herencia compleja, podrían tener la misma etiología genética en ambas poblaciones, lo que garantizaría las condiciones óptimas para estudios de cartografía genética.

Introduction. Surname frequency (isonymy) is used as a marker of paternal lineage and is used to characterize human population structure. Principles of isonymy were used to determine the genetic structure, migration rates, ancestry relations and origins of populations. This analysis was applied to two historically related local populations which currently are considered to be genetically isolated. Objective. The genetic relationships and influence zones of the Aranzazu and Marinilla populations were assessed by means of surname frequency analysis. Materials and methods. Data originated from database with the title “System of Identification of Beneficiaries of the Social Programs” database or Sisben. Population parameters such as a priori kinship (fii), population homogeneity with B and C estimators, and Cavalli-Sforza’s genetic distance were calculated for (a) three towns of Marinilla and its influence zone and (b) Aranzazu. The Rionegro population served as an external, comparison population. Results. The Aranzazu and Marinilla populations showed the higher homogeneity (B value between 0.25 and 0.5) in contrast with Rionegro (B = 0.159), as well as greater a priori kinship values (fii between 0.003 and 0.010). The lowest distances were found between Marinilla and Aranzazu. Conclusions. Aranzazu is a population with characteristics similar to those of Marinilla and its influence zone. The close similarity of genetic characteristics for these populations is due probably to a founder effect. Furthermore, the genetic similarity predicts that genetic diseases will have the same etiology in both populations and provides optimum conditions for gene mapping studies.

[Analysis of common mutations in GJB2 and GJB6 genes in patients with autosomal recessive non-syndromic hearing loss in Eastern Azerbaijan]

Profound hearing loss is one of the most prevalent congenital disorders affecting about 1 in 1000 newborns. Autosomal recessive non-syndromic hearing loss [ARNSHL] is the predominant form of the severe inherited childhood deafness. This type of hearing loss in one-half of the cases is caused by mutations in GJB2 [connexin 26] and GJB6 [connexin 30] genes located at DFNB 1 locus of chromosome13q. Protein products of the two above-mentioned genes play a crucial role in the intercellular communications within the inner ear through gap junction. This study was conducted to analyze the two most common mutations among ARNSHL patients referring to the Genetics center of Tabriz, eastern Azarbaijan. The most common mutation of GJB2 gene [35delG] and a mutation of GJB6 gene [del[GJB6-D13S1830]] were analyzed in 129 referring patients with ARNSHL using ARMS-PCR and multiplex-PCR techniques, respectively. These methods facilitate analyzing parents and carriers. 21% of the studied families had 35delG mutation in connexin 26 gene. 36 chromosomes [18%] out of 200 studied chromosomes had 35delG mutation while none of the chromosomes had del [GJB6-D 13S 1830] mutation in connexin 30. The 35delG mutation was assessed in parents and siblings in order to detect carriers. 35delG mutation accounts for 18% of ARNSHL in eastern Azerbaijan which is various to other published studies from different regions of Iran. The absence of del [GJB6-D13S1830] mutation in the patients may be due to the founder effect