RESUMO
Infantile and childhood-onset cataracts form a heterogeneous group of disorders; among the many genetic causes, numerous pathogenic variants in additional genes associated with autosomal-recessive infantile cataracts remain to be discovered. We identified three consanguineous families affected by bilateral infantile cataracts. Using exome sequencing, we found homozygous loss-of-function variants in DNMBP: nonsense variant c.811C>T (p.Arg271∗) in large family F385 (nine affected individuals; LOD score = 5.18 at θ = 0), frameshift deletion c.2947_2948del (p.Asp983∗) in family F372 (two affected individuals), and frameshift variant c.2852_2855del (p.Thr951Metfs∗41) in family F3 (one affected individual). The phenotypes of all affected individuals include infantile-onset cataracts. RNAi-mediated knockdown of the Drosophila ortholog still life (sif), enriched in lens-secreting cells, affects the development of these cells as well as the localization of E-cadherin, alters the distribution of septate junctions in adjacent cone cells, and leads to a â¼50% reduction in electroretinography amplitudes in young flies. DNMBP regulates the shape of tight junctions, which correspond to the septate junctions in invertebrates, as well as the assembly pattern of E-cadherin in human epithelial cells. E-cadherin has an important role in lens vesicle separation and lens epithelial cell survival in humans. We therefore conclude that DNMBP loss-of-function variants cause infantile-onset cataracts in humans.
Assuntos
Catarata/genética , Proteínas do Citoesqueleto/genética , Predisposição Genética para Doença/genética , Variação Genética/genética , Perda de Heterozigosidade/genética , Adulto , Alelos , Animais , Caderinas/genética , Criança , Drosophila/genética , Células Epiteliais/patologia , Exoma/genética , Feminino , Homozigoto , Humanos , Escore Lod , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Junções Íntimas/patologiaRESUMO
Robertsonian translocations are the most common form of chromosomal abnormalities that specifically involve the acrocentric chromosomes. Robertsonian translocation between chromosomes 13,14 and 14,21 are the most frequently reported. Infertility is common in genetically balanced carriers of these translocations, and their conceptions are more likely to have imbalances. Here we have reported a case of an 18-year-old female presenting with a complaint of primary amenorrhea. Cytogenetic analysis revealed a familial case of maternally inherited Robertsonian translocation (rob(13;14)(q10;q10)) affecting all the siblings. Genetic counseling and genetic testing are recommended especially in familial cases as the carriers are normal but can lead to several genetic disorders in their future generation.