Médecine moléculaire et génétique

Spectrum of Mutations in WFS1 Gene in Six Families with Wolfram Syndrome: Identification of Five Novel Mutations

Abstract

Gupta D, Bhai P, Saxena R, Bijarnia-Mahay S, Puri RD, Verma IC, Das L, Bhansali A and Shanker V

Background: Wolfram syndrome is a neurodegenerative disorder characterized by the acronym DIDMOAD (Diabetes Insipidus (DI), Diabetes Mellitus (DM), Optic Atrophy (OA) and Deafness). Homozygous/compound heterozygous mutations in WFS1 gene causes autosomal recessive form of Wolfram syndrome (AR-WS) whereas heterozygous mutations are associated with autosomal dominant-low-frequency non-syndromic hearing loss (ADLFNSHL). Clinical symptoms and degree of severity is reported to be heterogeneous in WS patients.
Aim: To characterize clinical features and molecular gene mutations in patients with WS in India and compare them with data from other countries.
Patients and Methodology: Eleven patients from 6 families were enrolled. In nine patients from 4 families with phenotypic features of diabetes mellitus, optical atrophy and hearing loss WFS1 gene was sequenced. Two patients of the other 2 families presented with hearing loss only and were analysed for targeted deafness genes panel by next generation sequencing.
Results: Nine patients from 4 families had biallelic mutations in WFS1 gene. Two patients harboured heterozygous mutation in WFS1 gene. Seven different mutations WFS1 were identified, of which 5 mutations were novel. All the identified mutations were present in exon 8 of WFS1 gene.
Conclusion: Pathogenic variations in WFS1 gene can cause both AR-WS and AD-LFNSHL. We recommend a protocol in which patients with WS should be first sequenced for the hotspot exon 8. If no mutation is identified, then the full gene should be sequenced. Further, for patients with hearing loss with/without diabetes and/or optical atrophy, WS should be considered as one of the differential diagnosis.