A compound heterozygous mutation in the S-Antigen Visual Arrestin SAG gene in a Chinese patient with Oguchi type one: a case report

Abstract

Background Oguchi disease is a rare autosomal recessive form of congenital quiescent night blindness. Oguchi disease has been found to be associated with gene mutations in SAG and GRK1, which are vital factors in the recovery phase of phototransduction after light stimuli. We report a case of Oguchi disease with novel heterozygous mutations in SAG. Case presentation A 7-year-old girl with a history of night blindness since childhood, was referred to our hospital. Ophthalmologic examinations included visual acuity, fundus examinations, fundus photography, spectral-domain optical coherence tomography, electroretinographic (ERG). Mutation screening of the SAG and GRK1 genes was performed. This patient exhibited typical clinical characteristics of Oguchi disease, including night blindness, golden fundus with the Mizuo–Nakamura phenomenon, packed structure of the parafovea in optical coherence tomography and reduced a-waves and b-waves in scotopic 3.0 ERG. Genetic testing revealed a heterozygous change in nucleotide c.72_75+15delATCGGTGAGTGGTGCACAA in exon 2 of the SAG gene in this patient, her unaffected mother and younger brother. A splicing alteration of nucleotide c.376-2A>C was identified in exon 6 of the SAG gene with heterozygous status in this patient and her unaffected father. Conclusions Compound heterozygosity of a nonsense p.S25X mutation in exon 2 and a splicing alteration in exon 6 of the SAG gene is the cause of this patient with Oguchi type 1 disease in China.

Mutation analysis reveals novel and known mutations in SAG gene in first two Egyptian families with Oguchi disease

“…c.649-1 G > C splice site mutation is predicted to hinder the proper transcription of the gene and hence the proper production of normal mRNA which might be subjected to nonsense mediated mRNA decay or end up in an aberrant nonfunctioning protein. This splice site variant is the third to be found in SAG gene as the first splice site mutation in SAG gene was described by Liu et al in a Chinese Oguchi patient in a homozygous form [21] and the second one was described in another Chinese Oguchi patient in a compound heterozygous form [33].…”