Juvenile Huntington's disease in northern Brazil: a case series report / Doença de Huntington juvenil no norte do Brasil: relato de uma série de casos

Introduction: Huntington's disease (HD) is a neurodegenerative disorder caused by CAG expansion repeats in the HTT gene. Usually, the symptoms start to manifest in mid-adulthood. In about 5% of cases, however, the signs begin before the age of 20 years. These cases are known as juvenile HD (JHD). Objective: here we report a case series of JHD from Amazonas, a state where data are scarce due to the restricted access to specialized medical assistance for diagnosis and care. Case series: the patients were attended by neurologists specialized in movement disorders at Manaus. Two cases manifested the disease in childhood (6 and 7 years old) and two cases, in adolescence (12 and 16 years old). All cases showed dystonia and parkinsonism as predominant motor disorders. Moreover, signs of cognitive decline, depression, and psychosis were observed in all patients. Conversely, cerebellar signs, gait disturbances, seizures, and some psychiatric symptoms were variable among the cases. Expansion size varied from 66 to 84 to CAG repeats and the difference in age at onset between parent and child varied from 23 to 43 years. Conclusion: to our knowledge, these are the first clinical reports of JHD in northern Brazil. These cases illustrate the variability in clinical phenotypes and genetic features of JHD cases. Furthermore, they can contribute to the awareness of HD here, both by professionals and the public in general.

Introdução: a doença de Huntington (DH) é um distúrbio neurodegenerativo causado pela expansão de repetições CAG no gene HTT. Geralmente, os sintomas começam a se manifestar na vida adulta tardia. Em cerca de 5% dos casos, no entanto, os sinais começam antes da idade de 20 anos. Esses casos são conhecidos como DH juvenil (DHJ). Objetivo: neste estudo, nós reportamos uma série de casos de DHJ do Amazonas, um estado onde os dados ainda são escassos devido ao acesso restrito à assistência médica especializada para o diagnóstico e cuidado. Série de casos: os pacientes foram atendidos por neurologistas especializados em transtornos do movimento em Manaus. Dois casos manifestaram a doença na infância (6 e 7 anos) e dois casos, na adolescência (12 e 16 anos). Todos os casos apresentaram distonia e parkinsonismo como sintomas motores predominantes. Sinais de declínio cognitivo, depressão e psicose também foram observados em todos os pacientes. Por outro lado, sinais cerebelares, distúrbios da marcha, convulsões e alguns sintomas psiquiátricos foram variáveis entre os casos. O tamanho da expansão CAG variou de 66 a 84 repetições e a diferença na idade de início dos sintomas entre pais e filhos variou de 23 a 43 anos. Conclusão: ao nosso conhecimento, estes são os primeiros relatos clínicos da DHJ na região Norte. Esses casos ilustram a variabilidade nos fenótipos clínicos e nas características genéticas dos casos de DHJ. Além disso, eles podem contribuir para a conscientização da DH na região, tanto pelos profissionais quanto pelo público geral.

Reduced penetrance in human inherited disease

For many inherited diseases, the same mutation is not always expressed in all persons who care it, moreover, when the mutation is expressed, it is not always expressed in the same way. These findings are the basis for the concepts of penetrance and expressivity. Understanding the factors that control penetrance of disease genes will provide insight into the fundamental disease processes and will help in genetic counselling. With the advancement of molecular genetics over the last few years, some of the underlying mechanisms of reduced penetrance have been elucidated. These include, mutation type, allelic variations in gene expression, epigenetic factors, gene-environment interplay, influence of age and sex, allele dosage, oligogenic and modifier genes, copy number variations as well as the influence of additional gene variants and the effect of single nucleotide polymorphisms. The aim of this review is to clarify factors affecting gene penetrance as well as some of the underlying molecular mechanisms in some genetic disorders

anticipation and inheritance pattern of c.487 A>G mutation in the GJB2 gene

Mutations in the GJB2 gene are the most common causes of hereditary hearing loss. This study reveals some facts about the inheritance pattern of M163V in the GJB2 gene. This study was performed on two different families with non-syndromic hearing loss. We screened the GJB2 coding region with direct sequencing. There was a substitution of A to G in exon 2 at nucleotide 487 [M163V]. This mutation was heterozygous in fathers and children while mothers were normal. Fathers of both families showed late onset hearing impairment, but there was early onset hearing loss in the children, which was more severe compared to the fathers. M163V has been reported as an unknown heterozygous mutation that leads to failure of the homotypic junctional channel formation. Another mutation in this codon is M163L, with an autosomal dominant inheritance, which impairs trafficking through the plasma membrane, resulting in cell death. Assessment of the familial pedigree has revealed anticipation in phenotype and autosomal dominant inheritance. These data in addition to the high conservation of methionine residue in mammalian species suggest that M163V is inherited with an autosomal dominant pattern. Therefore, the risk of inheritance will increase. Genetic counselors and otologists should prioritize the evaluation and prevention of this disorder in patients

Aspectos éticos dos testes preditivos em doenças de manifestação tardia / Ethical aspects of predictive tests for late-onset disorders

Discutem-se aqui, da perspectiva bioética, algumas das implicações da aplicação de testes pre-ditivos em doenças de manifestação tardia. São sugeridos questionamentos que podem ajudar a nortear a decisão sobre o uso dos testes preditivos e é feito um paralelo entre esses questionamentos e os princípios bioéticos de respeito à autonomia, justiça, beneficência e não maleficência. Observa-se, como resultado, a existência de uma preocupação com o resguardo de uma ética de vida em paralelo aos avanços tecnocientíficos no campo da Genética. Conclui-se pelo benefício de uma constante reflexão ética sobre a questão do diagnóstico prévio de doenças genéticas de início tardio.

The article discusses some of the bioethical implications of the application of predictive tests for late-onset disorders. Questions are raised which may help guide decision-making regarding the use of predictive tests along with issues connected with the bioethical principles of respect for autonomy, justice, beneficence and harm. It is observed that there is a concern to preserve a life-ethic that parallels technical and scientific advances in the field of genetics. It is concluded that it is always beneficial to engage in ethical reflection regarding the early diagnosis of late-onset genetic disorders.

Obesity, Insulin Resistance, and the Risk of Colonic Adenoma / 대한소화기학회지

No abstract availble.

SPG3A-hereditary spastin paraplegia with genetic anticipation and incomplete penetrance / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the SPG3A coding sequence and clinical features in a family with dominantly inherited hereditary spastin paraplegia (HSP) characterized by incomplete genetic penetrance and genetic anticipation.</p><p><b>METHODS</b>Analysis of the SPG3A coding sequence, being sequence variations in SPG4/spastin (S44L and P45Q) and SPG6/nipa1([GCG]5-11) genes were performed for the proband, his affected son, his unaffected parents and unaffected brother. One hundred normal individuals were selected as controls.</p><p><b>RESULTS</b>SPG3A mutation V253I in the proband, his affected son, and unexpectedly, in his asymptomatic, 72 year old father was identified. No mutation at the same site was found in the other members of this family as well as the control.</p><p><b>CONCLUSION</b>Incomplete genetic penetrance due to SPG3A mutation V253I was observed in this family. This is the second report. Marked phenotype variation (genetic non-penetrance, adult versus childhood onset symptoms) between subjects with the same SPG3A mutation indicates the influence of modifying genetic or environmental factors. Progressively earlier symptom onset and increasing symptom severity in this family is consistent with genetic anticipation which has not been previously reported in SPG3A-HSP.</p>

Molecular genetics of schizophrenia: past, present and future.

Schizophrenia is a severe neuropsychiatric disorder with a polygenic mode of inheritance which is also governed by non-genetic factors. Candidate genes identified on the basis of biochemical and pharmacological evidence are being tested for linkage and association studies. Neurotransmitters, especially dopamine and serotonin have been widely implicated in its etiology. Genome scan of all human chromosomes with closely spaced polymorphic markers is being used for linkage studies. The completion and availability of the first draft of Human Genome Sequence has provided a treasure-trove that can be utilized to gain insight into the so far inaccessible regions of the human genome. Significant technological advances for identification of single nucleo-tide polymorphisms (SNPs) and use of microarrays have further strengthened research methodologies for genetic analysis of complex traits. In this review, we summarize the evolution of schizophrenia genetics from the past to the present, current trends and future direction of research.

Diagnóstico molecular de la distrofia miotónica (DM) en Costa Rica / Molecular diagnostic of the myotonic dystrophy (MD) in Costa Rica

La Distrofía Miotónica es una enfermedad multisistémica de herencia autosómica dominante. El defecto molecular es una expansión del trinucleótico CTG presente en la región 3`no codificante (3ÙTR) del gen DMPK, localizado en el cromosoma 19q13.3. El objetivo del estudio fue implementar el diagnóstico molecular de la DM con el fin de contribuir a mejorar el manejo clínico de los pacientes afectados y a que el consejo genético sea más certero y preciso. El estudio se realizó en pacientes con diagnóstico clínico de DM y sus familiares, a los cuales se les confirmó el diangóstico mediante el uso de técnicas moleculares, a saber, la hibridación de Southern y la PCR. Se obtuvo el diagnóstico molecular de 84 pacientes de 21 diferentes familias; en 34 se diagnosticó el defecto molecular. En 21 personas de familias no se encontró la mutación. Se observó una correlación positiva entre la severidad de la enfermedad y el número de repeticiones CTG. Aquellos casos que resultaron negativos probablemente sean pacientes con mutaciones en otros genes, ya sea PROMM/DM2 u otras miotonias hereditarias. El diagnóstico molecular debe usarse como herramienta para lograr la clasificación clínica de los pacientes. El abordaje correcto de la enfermedad debido a que todavía no existe tratamiento, debe incluir, además del manejo clínico interdisciplinario, la prevención mediante el consejo genético basado en el diagnóstico molecular preciso de la condición de portador o portadora. Descriptores: Distrofia miotónica, mutaciones inestables, anticipación genética, Costa Rica, Hibridación de Southern, PCR, PROMM, consejo genético

Influencia de los factores genéticos del huésped en la infecci¢n por el virus de la inmunodeficiencia humana (VIH) / Influences of the guet`s genetic factors in the infection for the virus of the human inmunodeficiency

Después de la exposición a un patógeno, el huesped puede resistir la infección, permanecer sub-clínicamente infectado, o progresar a través de múltiples etapas desde una infección leve a estados muy severos. Secuelas crónicas pueden o no ocurrir. Una compleja trama de factores virales y del huésped, muchos de los cuales sólo recientemente se comienzan a entender; determinan el curso de la infección por VIH. La existencia de individuos que han estado expuestos y que no desarrollan la enfermedad (no infectados) sugiere la existencia de inmunidad natural y adquirida al VIH y esto es un determinante principal del resultado clínico. Hasta el presente han sido identificados diversos factores genéticos del huésped que determinan la infecci¢n por VIH. Varios genes y polimorfismos han sido identificados que confieren susceptibilidad (riesgo) y/o resistencia a la infección por VIH, entre los que podemos citar a los receptores de quemocinas y sus ligandos CCR-5 D32, CCR2-V64I, el factor 1 derivado de las células del estroma (SDF1), CX3CR1, y los polimorfismos del promotor de CCR5; los alelos clase I y II del HLA; as¡ como también los distintos factores inhibitorios; las citoquinas, que intervienen en las infecciones concominantes que afectan el curso clínico de la enfermedad, y un nuevo gen recientemente identificado, CEM15/APOBEC3G. Se discuten en esta revisi¢n, los aspectos relacionados con las interacciones entre los genes y sus efectos sobre la infecci¢n por VIH, las investigaciones relacionadas con estos genes, y las nuevas tendencias en el desarrollo de estrategias terapéuticas como la fármaco-genética y el desarrollo de vacunas, basados en el conocimiento de la genética molecular del virus y su huésped. La efectividad de dichas estrategias ayudará a trazar líneas de investigación y de desarrollo, en cuanto al control y prevenci¢n de la enfermedad

Dentatorubro-pallidoluysian Atrophy: The Clinical and Molecular Genetic Study of Three Korean Families

Dentatorubro-pallidoluysian atrophy (DRPLA) is a rare neurodegenerative disorder with various clinical phenotypes and has a cytosine-adenine-guanine (CAG) trinucleotide repeat in a gene on chromosome 12. It has been known that trinucleotide repeat disorders show strong inverse correlations between the CAG repeat number and the age of onset and genetic anticipation. The purpose of this study was to investigate whether these observations are applicable to Korean patients. This report involved three Korean families and had on file the history of the 15 affected family mem-bers .Seven of the affected members had the diagnosis of DRPLA which was confirmed by a gene study. We observed inverse correlations between the CAG repeat number and the age of onset and genetic anticipation with high intra- and interfamilial variations. Although our study was in general agreement with previously documented features of DRPLA, some features could not be explained by currently understood pathophysiologic mechanisms.

CAG Repeat Expansions in the Patients with Mood Disorder / 신경정신의학

OBJECTIVES: The genetic facotrs have been suggested for the etiology of mood disorders but the mode of inheritance is complex. Increased severity and an earlier onset of the bipolar and major depressive disorder over generations within families(Anticipation) were reported. In order to test the hypothesis that trinucleotide repeat expansions underlie the genetic basis of Bipolar and major depressive disorders, we have analyzed the extent of CAG reapeats in genomic DNA from mood disorder patients. METHODS: 55 bipolar disorder, 67 major depressive disorder patients were recruited according to the DSM-III-R criteria. 89 normal controls were recruited from the medical personnel, students and the visitors to the health services center who had no history of psychiatric illness and show normal profile of MMPI. The genomic DNA of patients and controls was analyzed by use of the(CTG) 17 oligonucleotide and the repeat expansion detection(RED) method. The Mann-Whitney U test was used to compare the distribution of the number of CAG repeats among the groups. RESULTS: when the bipolar disorder, major depressive disorder patients were compared with the control group, no significant differences were observed. CONCLUSION: Our results do not support the hypothesis that expanding CAG repeats are causing the observed genetic anticipation in bipolar disorders and major depressive disorders.

O fenômeno da antecipaçäo genética e a expansäo de repetiçöes trinucleotídicas no transtorno afetivo bipolar: análise de ligaçäo e associaçäo dos loci erda1, sef2-1b, hskca3 e mab21L com o transtorno afetivo bipolar / The Phenomenon of genetic anticipation and the trinucleotide repeats expansions in the bipolar affective disorder: linkage and association analysis of the erda1, sef2-1b, hSKCa3 and mab21L loci with the bipolar affective disorder

No início da década de 1990 descobriu-se que a base biológica para o fenômeno de antecipação genética era a expansão de grupos de três nucleotídios repetidos. Estudos recentes relatam a presença do fenômeno de antecipação em famílias com múltiplos afetados pelo transtorno afetivo bipolar. Ao lado disso, investigações independentes utilizando o método RED (Repeat Expansion Detection) - uma estratégia que detecta expansões de repetições trinucleotídicas no DNA genômico sem identificar sua localização têm mostrado associação entre este distúrbio do humor e longas repetições da seqüência nucleotídica CAG. No presente estudo testamos a hipótese de que loci com repetições CAG estão envolvidos na vulnerabilidade genética ao transtorno afetivo bipolar. Assim, analisamos o comprimento das repetições CAG presentes em quatro loci: o locus ERDA1 na região cromossômica l7q2l.3 ao qual tem sido atribuído a maioria das repetições CAG detectadas pelo RED, o locus SEF2-lb que situa-se na região l8q21.1, onde há relatos positivos de ligação e os loci hSKCa3 (região lq2l) e MAB2lL (região l3ql3), ambos devido a função do gene na qual as repetições residem. Inicialmente, investigamos quatorze famílias brasileiras com múltiplos afetados pelo transtorno bipolar, que tiveram a idade de início da doença comparada na 1ª e na 2ª geração revelando antecipação. Averiguamos ainda uma amostra de 115 pacientes bipolares não-aparentados e 196 indivíduos controles. As repetições CAG foram amplificadas por PCR, os produtos submetidos a eletroforese em gel de poliacrilamida e as bandas visualizadas após coloração com SYBR gold em aparelho de fluorescência direta (Fluorimager system), possibilitando definir os alelos de acordo com o tamanho da seqüência CAG. O teste ampliado para desequilíbrio de transmissão (ETDT) que utilizamos nas famílias não evidenciou transmissão preferencial de nenhum dos alelos para os membros afetados (ERDA1 X2=11,05/p=O,l36; SEF2-lb X2=4,42/p=O,62; hSKCa3 X2=0,88/p=O,92; MAB2lL X2=5,76/p=O,45). A análise de ligação por testes paramétricos e não-paramétricos excluiu ligação entre qualquer dos quatro loci e a doença bipolar (ERDA1 lod score= -lO,78/ p=O,27; SEF2-lb lod score= -5,87/p=O,6; hSKCa3 lod score=-2,Ol/p=O,59; MAB2lL lod score=-12,46/p=O,83). No estudo caso-controle, a distribuição dos alelos entre pacientes bipolares e controles foi comparada através do teste U de Mann-Whitney e não demonstrou diferenças significativas ...(au)

Clinical Significance of CTG Repeat Expansion in Korean Myotonic Dystrophy Patients

BACKGROUND: Myotonic dystrophy is the most common type of muscular dystrophy affecting adults, associated with the expansion of triplet repeat DNA sequences. A hallmark of the inherited disease with trinucleotide repeat DNA expansion is the clinical and genetic anticipation. The copy numbers of the CTG repeat are known to be related to the severity and the onset age of clinical symptoms. METHODS: The copy numbers of the CTG repeats were determined using PCR amplification and Southern blotting. The clinical manisfestations of 34 patients from 14 families who had the CTG repeat expansion were evaluated based on the muscular disability rating scale and the electrophysiological study. RESULTS: There was a significant positive correlation between the clinical scores and the size of the amplification of trinucleotide repeat, and a negative correlation with the age of onset. In 9 patients with copy numbers of CTG repeats between 61 and 100, 8 cases were asymptomatic and myotonic discharges were not seen in 71% of patients. Larger expanded bands, earlier onset, and worse symptoms were evident with each successive generation. CONCLUSIONS: Molecular genetic analysis with CTG repeat expansion might be useful in the detection and the genetic counseling of myotonic dystrophy patients.

Distrofia miotónica congénita / Congenital myotonic dystrophy

La distrofia miotónica es una patología que afecta tanto al músculo como a otros tejidos y órganos. Su etiología es genética, con una forma de herencia autosómica dominante y se caracteriza por presentar dos formas clínicas bien diferenciadas: la clásica del adulto y la congénita. Esta última, de pronóstico severo, ocurre únicamente en hijos de mujeres afectadas y sería una de las causas más frecuentes de hipotonía neonatal. Se presentan siete pacientes recién nacidos con distrofia miotónica congénita, se mencionan los mecanismos genéticos moleculares involucrados y se enfatiza la importancia del diagnóstico clínico de esta patología, a descartar en todo recién nacido hipotónico, sobre todo en casos de madres con escasa sintomatología.