Investigating the Molecular Basis of Retinal Degeneration in a Familial Cohort of Pakistani Decent by Exome Sequencing
PLOS ONE
Authors: Maranhao, Bruno; Biswas, Pooja; Gottsch, Alexander D. H.; Navani, Mili; Naeem, Muhammad Asif; Suk, John; Chu, Justin; Khan, Sheen N.; Poleman, Rachel; Akram, Javed; Riazuddin, Sheikh; Lee, Pauline; Riazuddin, S. Amer; Hejtmancik, J. Fielding; Ayyagari, Radha
Abstract
Purpose To define the molecular basis of retinal degeneration in consanguineous Pakistani pedigrees with early onset retinal degeneration. Methods A cohort of 277 individuals representing 26 pedigrees from the Punjab province of Pakistan was analyzed. Exomes were captured with commercial kits and sequenced on an Illumina HiSeq 2500. Candidate variants were identified using standard tools and analyzed using exomeSuite to detect all potentially pathogenic changes in genes implicated in retinal degeneration. Segregation analysis was performed by dideoxy sequencing and novel variants were additionally investigated for their presence in ethnicity-matched controls. Results We identified a total of nine causal mutations, including six novel variants in RPE65, LCA5, USH2A, CNGB1, FAM161A, CERKL and GUCY2D as the underlying cause of inherited retinal degenerations in 13 of 26 pedigrees. In addition to the causal variants, a total of 200 variants each observed in five or more unrelated pedigrees investigated in this study that were absent from the dbSNP, HapMap, 1000 Genomes, NHLBI ESP6500, and ExAC databases were identified, suggesting that they are common in, and unique to the Pakistani population. Conclusions We identified causal mutations associated with retinal degeneration in nearly half of the pedigrees investigated in this study through next generation whole exome sequencing. All novel variants detected in this study through exome sequencing have been cataloged providing a reference database of variants common in, and unique to the Pakistani population.
Alstrom Syndrome: Mutation Spectrum of ALMS1
HUMAN MUTATION
Authors: Marshall, Jan D.; Muller, Jean; Collin, Gayle B.; Milan, Gabriella; Kingsmore, Stephen F.; Dinwiddie, Darrell; Farrow, Emily G.; Miller, Neil A.; Favaretto, Francesca; Maffei, Pietro; Dollfus, Helene; Vettor, Roberto; Naggert, Juergen K.
Abstract
Alstrom Syndrome (ALMS), a recessive, monogenic ciliopathy caused by mutations in ALMS1, is typically characterized by multisystem involvement including early cone-rod retinal dystrophy and blindness, hearing loss, childhood obesity, type 2 diabetes mellitus, cardiomyopathy, fibrosis, and multiple organ failure. The precise function of ALMS1 remains elusive, but roles in endosomal and ciliary transport and cell cycle regulation have been shown. The aim of our study was to further define the spectrum of ALMS1 mutations in patients with clinical features of ALMS. Mutational analysis in a world-wide cohort of 204 families identified 109 novel mutations, extending the number of known ALMS1 mutations to 239 and highlighting the allelic heterogeneity of this disorder. This study represents the most comprehensive mutation analysis in patients with ALMS, identifying the largest number of novel mutations in a single study worldwide. Here, we also provide an overview of all ALMS1 mutations identified to date. (C) 2015 Wiley Periodicals, Inc.