1. Multiple Independent Gene Disorders Causing Bardet-Biedl Syndrome, Congenital Hypothyroidism, and Hearing Loss in a Single Indian Patient.
- Author
-
Peixoto de Barcelos I, Li D, Watson D, M McCormick E, Elden L, Aleman TS, O'Neil EC, J Falk M, and Hakonarson H
- Abstract
We report a 20-year-old, female, adopted Indian patient with over 662 Mb regions of homozy-gosity who presented with intellectual disability, ataxia, schizophrenia, retinal dystrophy, moder-ate-to-severe progressive sensorineural hearing loss (SNHL), congenital hypothyroidism, cleft mi-tral valve with mild mitral valve regurgitation, and dysmorphic features. Exome analysis first on a clinical basis and subsequently on research reanalysis uncovered pathogenic variants in three nu-clear genes following two modes of inheritance that were causal to her complex phenotype. These included (1) compound heterozygous variants in BBS6 potentially causative for Bardet-Biedl syn-drome 6; (2) a homozygous, known pathogenic variant in the stereocilin ( STRC ) gene associated with nonsyndromic deafness; and (3) a homozygous variant in dual oxidase 2 ( DUOX2 ) gene asso-ciated with congenital hypothyroidism. A variant of uncertain significance was identified in a fourth gene, troponin T2 ( TNNT2 ), associated with cardiomyopathy but not the cleft mitral valve, with mild mitral regurgitation seen in this case. This patient was the product of an apparent first-degree relationship, explaining the multiple independent inherited findings. This case high-lights the need to carefully evaluate multiple independent genetic etiologies for complex pheno-types, particularly in the case of consanguinity, rather than presuming unexplained features are expansions of known gene disorders.
- Published
- 2023
- Full Text
- View/download PDF