Identification of a variant in the USH1G gene in a family with Usher syndrome

Abstract

Usher syndrome is characterized by congenital sensorineural hearing loss, retinitis pigmentosa, and vestibular dysfunction. It is the most common cause of deafblindness worldwide. It is classified into three clinical types and twelve genetic subtypes. We report a case of a family affected by Usher syndrome due to a variant in the USH1G gene, coding for the SANS protein. The ocular and auditory tests were performed for clinical confirmation of the diagnosis. The molecular study consisted of a next-generation sequencing panel containing 14 genes associated with Usher syndrome: MYO7A, USHC1, CDH23, PCDH15, USHG1, CIB2, USH2A, ADGRV1, WHRN, CLRN1, HARS, PDZD7, CEP250, C2orf71. We present the case of a 13-year-old girl from a consanguineous Colombian family diagnosed with Usher syndrome type 1G. Clinical evaluations confirmed auditory, vestibular, and ocular alterations. Molecular analysis identified the homozygous p.Glu171Ter variant in the USH1G gene. We highlight the importance of an early diagnosis of Usher syndrome. Although the variant frequency in the USH1G gene is low, it should not be underestimated; the exact etiology must be identified in these families. We recommend establishing a panel with Colombianspecific variants to perform more accurate Usher syndrome diagnoses, and in the future, to guide the development of gene therapies.