Identification of Three Novel and One Known Mutation in the WFS1 Gene in Four Unrelated Turkish Families: The Role of Homozygosity Mapping in the Early Diagnosis

J Clin Res Pediatr Endocrinol. 2021 Feb 26;13(1):34-43. doi: 10.4274/jcrpe.galenos.2020.2020.0152. Epub 2020 Sep 17.

Abstract

Objective: Bi-allelic mutations in the wolframin gene (WFS1) cause Wolfram syndrome 1 (WS1 or DIDMOAD) characterized by nonautoimmune diabetes mellitus, optic atrophy, diabetes insipidus, sensorineural deafness, urinary tract abnormalities, and neuropsychiatric disorders. Patients presenting with an incomplete phenotype of WS1 were evaluated using homozygosity mapping and subsequent whole-exome sequencing.

Methods: Four unrelated consanguineous Turkish families, including seven affected children, and their unaffected parents and siblings were evaluated. Homozygosity mapping was performed, followed by whole-exome sequencing of WFS1. Mutations were classified according to results of “in silico” analyses, protein prediction, and functional consequences.

Results: Homozygosity mapping confirmed shared homozygous regions on chromosome 4 (chr4p16.1) between the affected individuals, that was absent in their unaffected siblings. Exome sequencing identified three novel (c.1215T>A, c.554G>A, c.1525_1540dup) and one known (c.1522_1523delTA) mutations in WFS1. All mutations were predicted to cause stop codon leading to early termination of protein synthesis and complete loss-of-function. All patients were found to be homozygous for the change, with parents and other unaffected siblings being carriers.

Conclusion: Our study expands the mutation spectrum of WSF1 mutations with three novel mutations. Homozygosity mapping may provide enrichment for molecular genetic analysis and early diagnosis of WS1 patients with incomplete phenotype, particularly in consanguineous pedigrees.

Keywords: WFS1; Wolfram syndrome; diabetes insipidus; diabetes mellitus; optic atrophy; sensorineural deafness.

Publication types

  • Case Reports

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Consanguinity
  • Female
  • Humans
  • Male
  • Membrane Proteins / genetics*
  • Pedigree
  • Turkey
  • Wolfram Syndrome / genetics*
  • Wolfram Syndrome / physiopathology*
  • Young Adult

Substances

  • Membrane Proteins
  • wolframin protein