Background: The characteristics of Waardenburg syndrome (WS) as a scarce heritable disorder are sensorineural hearing loss and deficits of pigmentation in the skin, hair, and eye. Here, clinical features and detection of the mutation in the MITF gene of WS2 patients are reported in a sizable Iranian family.
Methods: A man aged 28-years represented with symptoms of mild unilateral hearing loss (right ear), complete heterochromia iridis, premature graying prior to 30 years of age, and synophrys. In this research, there was a sizable family in Iran comprising three generations with seven WS patients and two healthy members. Whole exome sequencing was applied for proband for the identification of the candidate genetic mutations associated with the disease. The detected mutation in proband and investigated family members was validated by PCR-Sanger sequencing.
Results: A novel heterozygous mutation, NM_198159.3:c.1026dup p.(Asn343Glufs*27), in exon 9 of the MITF gene co-segregated with WS2 in the affected family members. The variant was forecasted as a disease-causing variant by the Mutation Taster. According to the UniProt database, this variant has been located in basic helix-loop-helix (bHLH) domain of the protein with critical role in DNA binding.
Conclusions: A frameshift was caused by a nucleotide insertion, c.1026dup, in exon 9 of the MITF gene. This mutation is able to induce an early termination, resulting in forming a truncated protein capable of affecting the normal function of the MITF protein. Helpful information is provided through an exactly described mutations involved in WS to clarify the molecular cause of clinical characteristics of WS and have a contribution to better genetic counseling of WS patients.
Keywords: Hearing loss; MITF; Waardenburg syndrome.
© 2021. The Author(s).