El niño plateado: Síndrome de Chediak-Higashi / The Silver Child: Chediak-Higashi Syndrome

El Síndrome de Chediak-Higashi (SCH) es una patología de herencia autosómica recesiva debido principalmente a mutaciones del gen regulador del tráfico lisosómico (LYST), causando grados dermatológicamente diferentes de albinismo óculocutáneo, infecciones recurrentes, disfunción fagocítica primaria, en el desarrollo y proliferación de todas las líneas celulares. Se presenta caso de preescolar masculino de 2 años de edad, ingresado por aumento de volumen bilateral en región cervical y fiebre, en malas condiciones generales, con áreas de hiperpigmentación en piel, cabello y cejas de coloración grisácea, adenopatías generalizadas y visceromegalias; leucocitosis con linfocitosis y neutropenia, anemia, trombocitopenia, hipoalbuminemia, hipertrigliceridemia e hiperferritinemia; en vista de la infrecuente coexistencia de dichas características con albinismo óculocutáneo; es evaluado por hematología y dermatología evidenciándose inclusiones citoplasmáticas y melanosomas gigantes, respectivamente, compatibles con SCH, confirmándose diagnóstico. El conocimiento del SCH es importante para la oportuna sospecha clínica-diagnóstica e inicio de protocolos terapéuticos en consenso, que garanticen un manejo eficaz para su sobrevida(AU)

Chediak-Higashi syndrome (SCH) is an auto somal recessive in herited pathology mainly due to mutations ofthe LYST gene, causing dermatologically different degrees of oculocutaneous albinism, recurrent infections, primary phagocytic dysfunction, in the development and proliferation of all cell lines. We present a case of a 2-year-old male preschool, admitted due to bilateral volume increase in thecervical region and fever, in poor general conditions, with areas of hyperpigmentation in skin, hair and eyebrows of grayish coloration, generalized lymphadenopathy and visceromegaly; leukocytosis with lymphocytosis and neutropenia, anemia, thrombocytopenia, hypoalbuminemia, hypertriglyceridemia,and hyperferritinemia; in view of the infrequent coexistence of these characteristics with oculocutaneous albinism; it isevaluated by hematology and dermatology, showing cytoplasmicinclusions and giant melanosomes, respectively, compatiblewith SCH, confirming the diagnosis. Knowledge of SCH is important for timely clinical-diagnostic suspicion and initiation of consensus therapeutic protocols that guarantee effective management for survival(AU)

Clinical and molecular genetic analysis of Angelman syndrome with oculocutaneous albinism type 2: A case report and literature review / 北京大学学报(医学版)

To summarize the clinical diagnosis and treatment process and genetic test results and characteristics of one child with Angelman syndrome (AS) complicated with oculocutaneous albinism type 2 (OCA2), and to review the literature. "Angelman syndrome" "P gene" and "Oculocutaneous albinism type 2" were used as keywords to search at CNKI, Wanfang, and PubMed databases (from creation to December 2019). Then all the patients were analyzed. The patient in this study was a girl aged 1 year. After birth, she was found to present as white body, yellow hair, and nystagmus. She could raise her head at the age of 2 months and turn over at the age of 7 months. The head circumference was 42 cm and she could not sit alone or speak at present. Trio-based exome sequencing revealed that the patient carried a homozygous mutation of c.168del (p.Gln58ArgfsTer44) in the P gene, and her father was heterozygous and her mother was wild-type. The detection of copy number variation showed deletion on the maternal chromosome at 15q11.2-13.1 region (P gene located in this region) in the patient. Until December 2019, a total of 4 cases in the 4 literature had been reported. Adding our case here, the 5 cases were summarized and found that all the cases showed white skin, golden hair, and shallow iris after birth. Comprehensive developmental delay was found around 6 months of age after birth, and the language remained undeveloped in 2 cases till follow-up into childhood. Seizures occurred in 4 patients. Two cases had ataxia. All the 5 cases had acquired microcephaly. Two cases had a family history of albinism. Electroencephalogram monitoring was completed in 3 cases and the results were abnormal. Genetic tests showed that all the 5 cases had deletion on maternal chromosome at 15q11-13 region. Four cases carried mutation of P gene on paternal chromosome. And 1 case was clinically diagnosed as OCA2 without P gene test. AS combined with OCA2 is relatively rare. OCA2 is easily diagnosed based on the obvious clinical manifestations after birth. When combined with clinical manifestations such as neurodevelopmental delay, it might indicate the possibility of AS that is hardly diagnosed clinically at an early stage. Genetic tests can reveal the cross-genetic phenomenon of AS and OCA2 and the complex of them can be eventually diagnosed.

Oculocutaneous albinism in southern Africa: Historical background, genetic, clinical and psychosocial issues

Albinism is an inherited condition associated with significant depigmentation of the skin, hair and eyes. It occurs in every population with varying frequency, and narratives of people with albinism have been recorded since 200 BC. In southern Africa albinism is common, about 1 in 4000 people are affected, but it remains a poorly understood condition surrounded by myths and superstition. This article provides a historical background on oculocutaneous albinism (OCA) in southern Africa and presents relevant information from the literature regarding epidemiology, genetics and genetic counselling, health, psychosocial and cultural issues, and medical care. There are several recessively inherited types of OCA and a mutation, responsible for about 80%of South African variants, has been identified in OCA type 2. The physical characteristics associated with albinism, that is, sun-sensitive skin and low vision, can be managed. However, people with OCA in Africa also experience psychosocial issues, such as discrimination, because of the various superstitious beliefs and attitudes held in the community. Management should include medical care for health problems, appropriate adjustment of the schooling context and genetic counseling. In addition, widespread public awareness programs are required to increase the knowledge of the genetic causes of OCA and of the nature of genetic counselling, to address the negative attitudes in the community, to reduce the marginalization and stigmatization of people with albinism and to improve their quality of life.

Oculocutaneous albinism in southern Africa: Historical background, genetic, clinical and psychosocial issues

Albinism is an inherited condition associated with significant depigmentation of the skin, hair and eyes. It occurs in every population with varying frequency, and narratives of people with albinism have been recorded since 200 BC. In southern Africa albinism is common, about 1 in 4000 people are affected, but it remains a poorly understood condition surrounded by myths and superstition. This article provides a historical background on oculocutaneous albinism (OCA) in southern Africa and presents relevant information from the literature regarding epidemiology, genetics and genetic counselling, health, psychosocial and cultural issues, and medical care. There are several recessively inherited types of OCA and a mutation, responsible for about 80%of South African variants, has been identified in OCA type 2. The physical characteristics associated with albinism, that is, sun-sensitive skin and low vision, can be managed. However, people with OCA in Africa also experience psychosocial issues, such as discrimination, because of the various superstitious beliefs and attitudes held in the community. Management should include medical care for health problems, appropriate adjustment of the schooling context and genetic counseling. In addition, widespread public awareness programmes are required to increase the knowledge of the genetic causes of OCA and of the nature of genetic counselling, to address the negative attitudes in the community, to reduce the marginalisation and stigmatization of people with albinism and to improve their quality of life

Genetic testing and prenatal diagnosis for thirteen Chinese pedigrees affected with oculocutaneous albinism / 中华医学遗传学杂志

OBJECTIVE@#To identify the causative variants in 13 Chinese pedigrees affected with oculocutaneous albinism (OCA) so as to provide genetic counseling and prenatal diagnosis to them.@*METHODS@#Thirteen unrelated pedigrees with clinically diagnosed OCA were collected and classified based on the manifestation of skin and eyes. With informed consent obtained from the participants, peripheral blood samples were collected from the probands and their family members for the extraction of genomic DNA. Candidate variants were screened by targeted capture and next generation sequencing, and the results were validated by Sanger sequencing. Prenatal diagnosis was provided to the families upon their subsequent pregnancies.@*RESULTS@#Causative variants were detected in all probands, including 10 with compound heterozygotes or homozygotes for TYR gene variants and 3 with compound heterozygotes for OCA2 gene variants. Among these, two variants [TYR: c.650G>C (p.Arg217Pro) and OCA2: c.516-2A>T] were unreported previously. The pathogenicity of the novel TYR: c.650G>C (p.Arg217Pro) variant was verified through bioinformatic analysis and prediction of three dimensional structure of the protein. Prenatal diagnosis was provided to 6 fetuses with a high risk for OCA. Four fetuses were found to be carriers, one did not carry the variants of the proband, and one was affected with OCA.@*CONCLUSION@#Identification of the pathogenic variants in the 13 probands, including 2 novel ones, has expanded the mutational spectrum of OCA and enabled genetic counseling and prenatal diagnosis for the families.

Prevalence of premalignant and malignant skin lesions in oculocutaneous albinism patients

SUMMARY OBJECTIVE: Oculocutaneous albinism describes a group of pigmentary disorders that lead to skin sensitivity and predisposition to skin malignances. Aims: To analyze clinical and epidemiological data in oculocutaneous albinism patients and to determine the prevalence of malignant skin lesions, assessing possible risk factors for skin cancer. METHODS: Cross-sectional study evaluating epidemiological data, habits of sun exposure and sun protection, and clinical examination of albino patients followed in a reference dermatology outpatient clinic in Brasil. Our primary outcome was the occurrence of malignant skin lesions in biopsied tissues. RESULTS: Of 74 patients analyzed, 11 (15%) had one or more suspicious lesions and were biopsied, of which 8 (72.7%) patients presented with basal cell carcinomas, 7 (63.3%) presented with squamous cell carcinoma, and 1 (9%) presented with melanoma. Moreover, 32(43%) patients presented with actinic keratosis. Age, female gender, previous history of sunburn, history of malignant lesions and history of sun exposure without photoprotection were associated with the presence of malignant lesions. Limitations: Unicentric, non-aleatory sample. CONCLUSIONS: There was a high prevalence of malignant and pre-malignant lesions in this population. Some potentially modifiable risk factors were associated with the occurrence of malignant skin lesions.

Non-invasive prenatal detection of ocutaneous albinism type I based on cfDNA barcode-enabled single-molecule test / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of non-invasive prenatal testing based on cfDNA barcode-enabled single-molecule test (cfBEST) for the prenatal diagnosis of oculocutaneous albinism type I in a family.@*METHODS@#Prenatal genetic diagnosis was carried out by using the cfBEST-based method as well as invasive prenatal diagnosis through amniocentesis. The outcome of the pregnancy was followed up.@*RESULTS@#Non-invasive prenatal testing based on cfBEST showed a fetal DNA concentration of 6.6%, with the proportion of c.929_930insC (p.Arg311Lysfs*7) and c.1037-7T>A mutations being 45.7% and 0%, respectively. The posterior frequency of the negative results was 1, suggesting that the fetus carried neither of the two mutations. The result was consistent with that of invasive prenatal diagnosis, and the follow-up found that the fetus was normal.@*CONCLUSION@#Non-invasive prenatal testing based on cfBEST can be used to detect maternal and fetal genotypes in maternal cell-free DNA, which is clinically feasible.

Study on TYR gene variant from a pedigree with oculocutaneous albinism / 中华医学遗传学杂志

OBJECTIVE@#To analyze gene variants in a Chinese pedigree with oculocutaneous albinism (OCA).@*METHODS@#Gene sequencing of the proband and his parents was performed using chip capture high-throughput sequencing and Sanger sequencing techniques, and PolyPhen-2, SIFT, MutationTaster, and FATHMM software were used to predict the function of new variants. At the same time,the pedigree and variant genes of 4 albinism patients from this pedigree were analyzed.@*RESULTS@#Sequencing results showed that the proband's TYR gene (NM_000372) has c.230G>A (p.Arg77Gln) and c.120_121insG (p.Asp42GlyfsTer35) compound heterozygous variants. The proband's father carries c.230G>A heterozygous variant, and the mother carries c.120_121insG heterozygous variant, indicating that the proband's two variants are from his father and mother. The former is a known missense variant, which can cause abnormal or loss of the original function of the protein polypeptide chain. The latter c.120_121insG(p.Asp42GlyfsTer35) is an unreported frameshift variant of the TYR gene subregion (EX1; CDS1). PolyPhen-2, SIFT, MutationTaster and FATHMM predictions are all prompted as "harmful variants". This variant caused the amino acid encoded protein to terminate prematurely, producing a truncated protein, which eventually formed a 76-amino acid short-type TYR protein instead of the 529-amino acid wild-type TYR protein. Through the pedigree analysis, the four patients in the pedigree are all of the same type of compound heterozygous variants, and the disease-causing genes are all from the patient's parents. They belong to a special form of consanguineous marriage within 5 generations.@*CONCLUSION@#The compound heterozygous variants of c.230G>A (p.Arg77Gln) and c.120_121insG (p.Asp42GlyfsTer35) of the TYR gene may underlie the disease in this pedigree. The gene sequencing results enrich the variant spectrum of the TYR gene, and has facilitated molecular diagnosis for the patient.

Hereditariedade do albinismo Oculocutâneo em um grupo populacional no estado da Bahia / Heredity of Oculocutaneous albinism in a population group in the state of Bahia

Objetivo: trazer conhecimentos sobre a hereditariedade do albinismo em famílias da Bahia, estado com estimativa de taxa elevada da característica. Métodos: pesquisa seccional descritiva por amostragem de conveniência, com consulta às fichas de atendimento do programa Genética e Sociedade (Instituto de Biologia- UFBA) e ao banco de dados da Associação de Pessoas com Albinismo da Bahia (APALBA). Resultados: no total de 457 albinos, verificaram-se 265 com mais de um caso de albinismo na família (58%). Casais formados por pessoas albinas tiveram filhos com a mesma característica, o que concorda com o modelo clássico de herança autossômica recessiva para o albinismo, que preconiza nesta situação 100% dos filhos também albinos. Entretanto, em uma família, o casal albino com traços fenotípicos de diferentes subtipos teve um filho pigmentado com avaliação oftalmológica normal. Essa ocorrência foi associada à heterogeneidade genética do albinismo parental. Conclusões: estudos sobre a transmissão hereditária do albinismo em populações numerosas podem trazer contribuições para escolhas reprodutivas, aconselhamento genético e acompanhamento em saúde, tendo em vista a implantação precoce de medidas preventivas de danos à pele e à visão.

Objective: this study aimed to bring knowledge about the heredity of albinism in families from Bahia, a state with an estimated high rate of the characteristic. Methods: descriptive sectional survey by convenience sampling, with consultation to records of admission of the Genetics and Society program (Institute of Biology- UFBA) and the database of the Association of People with Albinism in Bahia (APALBA). Results: in a total of 457 albinos, there were 265 with more than one case of albinism in the family (58%). Albino couples had children with the same characteristic, which agrees with the classic model of autosomal recessive inheritance for albinism, which advocates that in this situation 100% of the children are also albinos. However, in one of these families, the albino couple with phenotypic traits of different subtypes had a pigmented child with normal ophthalmological evaluation. This occurrence was associated with the genetic heterogeneity of parental albinism. Conclusions: studies about hereditary transmission of albinism in large populations can contribute to reproductive choices, genetic counseling, and health monitoring, with a view to early implementation of preventive measures for skin and vision damage.

Molecular detection of albinism gene in Brazilian buffalo herds (Bubalus bubalis) / Detecção molecular do gene do albinismo em rebanhos de búfalos (Bubalus bubalis) do Brasil

Albinism is a genetic disease characterized by deficient melanin production making affected animals more susceptible to skin problems, negatively influencing production systems of the same. In buffalo, a nonsense mutation (c.1431G>A) in the tyrosinase gene was already described, which is responsible for the oculocutaneous albinism buffalo phenotype. However, prevalence studies have never been performed for this anomaly in Brazil. Therefore, the objective of this study was to investigate this mutation in buffalo herd in Brazil. Of the 315 buffalo tested with no albinism phenotype evident, 11 (3.5%) were heterozygous for the mutation and none were mutated homozygous, showing the existence of the albinism gene in buffalo production herds and proving the importance of prevalence studies for hereditary diseases in order to prevent the dissemination of these same genes and their negative productivity consequences.(AU)

O Albinismo é uma doença genética caracterizada pela deficiência na produção de melanina, o que torna os animais afetados mais susceptíveis a problemas cutâneos e influencia negativamente a criação destes animais. A mutação nonsense (c.1431G>A) no gene da tyrosinase já foi descrita como responsável pelo albinismo oculocutâneo em búfalos, entretanto estudos prévios sobre a prevalência dessa mutação ainda não foram realizados no Brasil. Portanto, o objetivo deste estudo foi avaliar a presença desta mutação em uma população de búfalos brasileiros. Foram genotipados 315 búfalos clinicamente normais, ou seja, sem o fenótipo albino evidente. Desses, 11 (3,5%) eram heterozigotos para a mutação (N/TYR) e os demais eram homozigotos selvagens (N/N). Este resultado demonstra que o alelo mutado para o albinismo em búfalo está presente no rebanho brasileiro e aponta a importância de estudos de prevalência de enfermidades hereditárias com o objetivo de prevenir a disseminação desses alelos mutados, minimizando os prejuízos.(AU)

Analysis of P gene variations among fourteen patients with oculocutaneous albinism type II / 中华医学遗传学杂志

OBJECTIVE@#To analyze variations of TYR and P genes among 14 patients with clinically diagnosed oculocutaneous albinism.@*METHODS@#Potential variations of the TYR and P genes were detected by Sanger sequencing. Novel variations were predicted with bioinformatics software including SIFT and PolyPhen-2.@*RESULTS@#No variation was found in the TYR gene, while 9 types of variations were found in the P gene among the 14 patients, which included c.803-3C>G (7/26), c.1327G>A (p.Val443Ile) (5/26), c.632C>T (p.Pro211Leu) (4/26), c.1832T>C (p.Leu611Pro) (3/26), c.1349C>A (p.Thr450Lys) (2/26), c.2363C>T (p.Ser788Leu) (2/26), c.2228C>T (p.Pro743Leu) (1/26), c.1525A>G (p.Thr509Ala) (1/26), and c.1349C>T (p.Thr450Met) (1/26). Only 1 heterozygous variation was detected in 2 families. c.2363C>T (p.Ser788Leu), c.1832T>C (p.Leu611Pro) and c.1525A>G (p.Thr509Ala) were not reported previously and predicted as "harmful" to the protein function.@*CONCLUSION@#The main type of ocular albinism is oculocutaneous albinism type II in Liuzhou region, where the most common variations of the P gene were c.803-3C>G and c.1327G>A (p.Val443Ile). Above finding has enriched the variation spectrum of the P gene.

Mutation analysis of two pedigrees with suspected oculocutaneous albinism / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical presentation and gene of 2 pedigrees with suspected oculocutaneous albinism(OCA), and provide basis for clinical classification, genetic counseling and prenatal diagnosis.@*METHODS@#Variants were identified using next-generation sequencing(NGS) and confirmed by Sanger sequencing in 2 pedigrees with suspected OCA. The pathogenicity of the variants was analyzed according to the American College of Medical Genetics and Genomics (ACMG) standard.@*RESULTS@#Two compound heterozygous mutations of TYR and OCA2 genes were identified respectively in 2 pedigrees with suspected OCA. The mutation of c.819+3insATATGCC in TYR and the mutation of c.1870G>C in OCA2 are first reported in this study. The pathogenicity analysis shows that two novel mutations are likely pathogenic by combination of prediction of SIFT, Polyphen-2 and Human Splicing Finder.@*CONCLUSION@#The findings of this study expand the mutational spectrum of OCA. Compound heterozygous mutations in the TYR and OCA2 gene may be responsible for clinical manifestations of 2 pedigrees with suspected OCA.

Diagnosis of a case with oculocutaneous albinism type Ⅲ with next generation exome capture sequencing / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the clinical and genetic features of a Chinese boy with oculocutaneous albinism.</p><p><b>METHODS</b>The clinical features of the patient were analyzed. The DNA of the patient and his parents was extracted and sequenced by next generation exome capture sequencing. The nature and impact of detected mutation were predicted and validated.</p><p><b>RESULTS</b>The child has displayed strabismus, poor vision, nystagmus and brown hair. DNA sequencing showed that the patient has carried compound heterozygous mutations of the TYRP1 gene, namely c.1214C>A (p.T405N) and c.1333dupG, which were inherited from his mother and father, respectively. Neither mutation was reported previously.</p><p><b>CONCLUSION</b>The child has suffered from oculocutaneous albinism type Ⅲ caused by mutations of the TYRP1 gene.</p>

Reevaluation of Single Nucleotide Polymorphism of OCA2 in Koreans / 체질인류학회지

Oculocutaneous albinism type 2 (OCA2) is an autosomal recessive disorder that results from mutations in the P gene, and has approximately 70% function of melanin biosynthesis in the melanocytes. While the overwhelming majority of pigmentation studies have focused on European populations, very little is known about the gene and mechanisms affecting skin lightening in Asian population. The main goal of the study was to test the distribution of three polymorphisms located in a pigmentation candidate gene, OCA2, in a sample of individuals of Koreans (N=250). The genetic markers were selected for polymorphisms that had an allele frequency difference of at least 30% between East Asian populations and European populations. We investigated Minor Allele Frequencies (MAFs) for each of three polymorphisms within OCA2 and reevaluated the difference of the allele frequency along with populations. MAFs of polymorphisms of OCA2 were presented the different frequency in Korean samples (SNP rs1800414 (His615Arg), A allele=38.8%, rs74653330 (Ala481Thr), A allele=0.8% and rs7497270 (intronic polymorphism), C allele=33.4%). While our results had different distributions to European and Caucasians, they showed similar frequencies with East Asian. This study was to reevaluate the distribution of pigmentation candidate gene in Korean samples, further domestic study will aid in developments of the genetic information on worldwide study.

Hypopigmented mycosis of fungoides in an eight-year-old girl managed with narrowband ultraviolet B therapy

Mycosis fungoides presenting with hypopigmented lesions is an uncommon variant, which is usually described among dark-skinned patients. We report a case of hypopigmented mycosis fungoides in an eight-year-old girl who has responded favorably to narrowband-ultraviolet B therapy. The disease mimics several benign inflammatory skin conditions, hence, a high clinical suspicion is warranted in patients presenting with widespread hypopigmentation.

Quality of life in patients with oculocutaneous albinism

AbstractBACKGROUND:The social reality of the albino needs to be more studied in Brazil, as myths and social segregation regarding this illness are likely to be found in the country, with psychosocial and medical implications.OBJECTIVE:As this subject has not been referenced in previous scientific articles in Brazil, this research intends to evaluate the quality of life of the albinos that treated at our medical institution.METHODS:The quality of life was evaluated through the WHOQOL-BREF. Furthermore, two aspects of main relevance in the lives of the albinos were also objects of research, low vision and skin cancer. The sample consisted of forty oculocutaneous albinos and a control group of forty healthy individuals, matched by sex and age.RESULTS:Among the participants, 57.7% were between 18 and 40 years old, 28.2% were between 41 and 60, and 14.1% were over 60. 42.1% had skin cancer before the study, 18.4% had skin cancer during the study and 89.5% stated visual deficit. The results obtained in the questionnaires showed a statistically significant difference in the physical domain, with P < 0.001.CONCLUSION:Low vision combined with skin lesions and social stigma may contribute to disturbances in the quality of life of oculocutaneous albinos. The results presented in this study demonstrated the vulnerability of the affected individuals and the special care required by those patients, at the same time that the need for further research is highlighted in order to better elucidate the aspects related to albinism.

Suspected pathogenic mutation identified in two cases with oculocutaneous albinism / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutations in genes related with non-syndromic oculocutaneous albinism I-IV and ocular albinism type I in two couples who had given births to children with albinism.</p><p><b>METHODS</b>All exons of the non-syndromic albinism related genes TYR, OCA2, TYRP-1, MITF, SLC45A2 and GPR143 were subjected to deep sequencing. The results were verified with Sanger sequencing.</p><p><b>RESULTS</b>For the two female carriers, the coding region of the TYR gene was found to harbor a frameshift mutation c.925_926insC, which was also suspected to have been pathogenic. In one of the male partners, a nonsense mutations c.832C>T was found, which was also known to be pathogenic. Another male partner was found to harbor a TYR gene mutation c.346C>T, which was also known to be a pathogenic nonsense mutation.</p><p><b>CONCLUSION</b>The coding region of the TYR gene c.925_926insC (p.Thr309ThrfsX9) probably underlies the OCA1 disease phenotype.</p>

Mellizas con albinismo oculocutáneo / Twins with oculocutaneous albinism

El albinismo oculocutáneo (AOC) comprende un grupo de trastornos de herencia autosómica recesiva, producidos por una alteración en la vía sintética de la melanina en la piel, el peloy los ojos. Clínicamente se caracteriza por lahipopigmentación cutánea, ocular y pilar, asociada a alteraciones oculares, como fotofobia severa, disminución de la agudeza visualynistagmo. El AOC tipo 1es producido por mutaciones en latirosinasa, enzima codificada por el genTYR (11q14-q21), habiéndose identificado más de 270 mutacioneshasta la fecha. Presentamos el caso de mellizasnacidas pretérmino, de 14 meses de vida, producto de un embarazo controlado, con AOC. Destacamos la escasa frecuencia de presentación de esta patología en pacientes mellizos.

Oculocutaneous albinism (OCA) is an autosomal recessive disorder caused by a defective synthesis of melanin in the skin, hair and eyes. It is clinically characterized by a generalized reduction of pigment in the skin, eyes and hair, associated with ocular alterations, as severe photosensitivity, reduced vision and nystagmus.The OCA type 1 is caused by mutations in the tyrosinase, enzyme that is codified by TYR (11q14-q21), with more than 270 mutations identified up to date. We report the case of preterm 14 month-olddizygotic females twinsfrom a controlled pregnancy, with OCA. We emphasize the low frequency of presentation of this disease in dizygotic twins.

Prenatal genetic diagnosis of oculocutaneous albinism type II through mutation detection combined with SNPs linkage analysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide prenatal diagnosis for two families affected with oculocutaneous albinism (OCA), in both of which only 1 pathogenic allele has been identified.</p><p><b>METHODS</b>To determine the clinical classification of OCA through DNA sequencing for TYR, P, TYRP1 and SLC45A2 genes in combination with phenotype analysis. Prenatal diagnosis was carried out by direct sequencing and intragenic SNPs family-based linkage analysis.</p><p><b>RESULTS</b>In the first family, only 1 heterozygous mutation c.1255C>T was found in the proband, which was inherited from her mother. Together with its clinical phenotype, the proband was suspected to have OCA2 Screening of amniotic fluid, however, has found no mutation. With family-based linkage analysis, the fetus was deemed to be an OCA2 carrier. In the second family, again only one heterozygous mutation c.1920_1949 del30bp and ins AACA was found in the proband, which was inherited from her father. Together with its clinical phenotype, the proband was suspected to have OCA2. Screening of amniotic fluid has revealed a heterozygous mutation c.1920_1949 del30bp and ins AACA. By family-based linkage analysis, the fetus was deemed to be an OCA2 carrier. Both fetuses had a normal phenotype at birth.</p><p><b>CONCLUSION</b>Prenatal genetic diagnosis has been provided for the first time for two families affected with OCA, in which only 1 pathogenic mutant allele was detected. The combined mutation detection and SNPs linkage analysis has turned out to be successful.</p>

Prenatal genetic diagnosis for two Chinese families affected with oculocutaneous albinism type Ⅱ / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform genotyping analysis and subsequent prenatal genetic diagnosis for two families affected with oculocutaneous albinism (OCA).</p><p><b>METHODS</b>Direct sequencing of TYR and P genes was performed in two albino probands. Family members were screened for corresponding mutant alleles. Prenatal genetic diagnoses were performed at early pregnancy by chorionic villus sampling (CVS) at mid-pregnancy through amniocentesis.</p><p><b>RESULTS</b>No mutations were detected in the TYR gene in either probands, whereas 4 heterozygous mutations of the P gene were found, namely c.406C>T, c.535A>G, c.808-2A>G and c.2180T>C, among which c.535A>G and c.808-2A>G were novel. In the first round prenatal genetic testing, both fetuses were found to have the same genotypes as the probands. Both families had decided to terminate the pregnancy after genetic counseling. In the second round testing, neither of the fetuses was found to be affected by genotyping. The pregnancies continued and two healthy fetuses were born.</p><p><b>CONCLUSION</b>OCA can be classified by genotyping, with which reliable prenatal diagnosis and feasible genetic counseling may be provided.</p>