Best-corrected visual acuity results facilitate molecular diagnosis of infantile nystagmus patients harboring FRMD7 mutations

Abstract

The visual function of patients with infantile nystagmus (IN) can be significantly decreased owing to constant eye movement. While, reaching a definitive diagnosis becomes a challenge due to genetic heterozygous of this disease. To address it, we investigated whether best-corrected visual acuity (BCVA) results can facilitate the molecular diagnosis of IN patients harboring FRMD7 mutations. 200 patients with IN from 55 families and 133 sporadic cases were enrolled. Mutations were comprehensively screened by direct sequencing using gene-specific primers for FRMD7. We also retrieved related literature to verify the results based on our data. We found that the BCVA of patients with IN harboring FRMD7 mutations was between 0.5 and 0.7, which was confirmed by data retrieved from the literature. Our results showed that BCVA results facilitate the molecular diagnosis of patients with IN harboring FRMD7 mutations. In addition, we identified 31 FRMD7 mutations from the patients, including six novel mutations, namely, frameshift mutation c.1492_1493insT (p.Y498LfsTer14), splice-site mutation c.353C > G, three missense mutations [c.208C > G (p.P70A), c.234G > A (p.M78I), and c.1109G > A (p.H370R)], and nonsense mutation c.1195G > T (p.E399Ter). This study demonstrates that BCVA results may facilitate the molecular diagnosis of IN patients harboring FRMD7 mutations.

Keywords: Best-corrected visual acuity; FRMD7; Infantile nystagmus; Molecular diagnosis; Mutation.