Clinical Characteristics and Genetic Mutations of Chinese Patients with X-linked Retinoschisis

  Objective  To assess the clinical features and to identify genetic mutations in Chinese patients with X-linked retinoschisis (XLRS).

  Methods  Patients were recruited from ophthalmic clinics in Peking Union Medical College Hospital. A cohort of five unrelated XLRS families (including 12 XLRS patients), 10 sporadic XLRS patients, 16 female carriers and 100 normal subjects were enrolled in this study. Clinical evaluation was performed on all probands from 5 unrelated families and 10 sporadic cases involved in this study (15 patients in total). Genomic DNA was extracted from the peripheral leukocytes of 22 patients and 16 carriers. All exons and the flanking introns of the RS 1 gene were amplified by polymerase chain reaction and screened for mutations by direct DNA sequencing.

  Results  A total of 11 mutations including p. E72K, p. W92C, p. R102Q, p. W112X, p. S134P, p. R156G, p. P193S, p. R200H, p. R209C, p. R213W and p. R213Q were identified, among which p. W112X and p. S134P were two novel mutations. We did not find any mutation in one sporadic case. Clinical evaluation on patients with RS1 mutation (14 patients in total) showed that reduced visual acuity was the common initial symptom in all 14 patients. The best corrected visual acuity ranged from 0.04 to 0.8. Typical foveal schisis was found in all 14 patients, among whom 6 were found to be with peripheral schisis. Electroretinogram was carried out on 10 patients with RS1 gene mutations and 9 of them displayed electronegative in the standard combined response. Patients with same RS1 mutation exhibited remarkable phenotypic differences.

  Conclusions  Chinese patients with XLRS displayed variability in clinical phenotypes. No association was found between the genotypes and phenotypes.