ObjectiveTo identify the pathogenic mutation in a three generation Chinese family with low penetrance retinoblastoma (RB). Methods8 from 9 family members received complete ophthalmic examinations. DNA was extracted from 6 family members. Using exon combined target region capture sequencing chip to screen the candidate disease-causing mutations. Sanger sequencing were used to confirm the disease-causing mutation. ResultsAmong 9 family members, the proband (Ⅲ2) was bilateral RB, Ⅲ1 was unilateral RB, Ⅲ3 was dead for bilateral RB. Normal fundus were observed in the left eye ofⅢ1 and the eyes of other family members except the proband. Sequence analysis of RB1 gene revealed a missense mutation c.1981C > T (p.Arg661Trp) in the proband and two carriers (Ⅱ2, Ⅱ3), but not in the two normal subjects (Ⅱ1, Ⅱ4). We suspect that the RB penetrance in the family was 50%. ConclusionsThere is a missense mutation c.1981C > T in a Chinese family with low penetrance RB. The RB penetrance is 50%.
ObjectiveTo observe the disease-causing genes and the inheritance in sporadic retinitis pigmentosa (sRP) in Ningxia region. Methods49 sRP patients and 128 family members were recruited for this study. All the patients and family members received complete ophthalmic examinations including best corrected visual acuity, slit-lamp microscope, indirect ophthalmoscopy, fundus color photography, visual field, optic coherence tomography, full view electroretinogram. DNA was extracted from patients and family members. Using exon combined target region capture sequencing chip to screen the 230 candidate disease-causing gene mutations, polymerase chain reaction and direct sequencing were used to confirm the disease-causing mutations. Results24/49 patients (49.0%) had identified disease-causing genes, totally 16 genes were involved. There were 41 mutation sites were found, including 32 new mutations (78.0%). The disease-causing genes include USH2A, C2orf71, GNGA1, RPGR1, IFT140, TULP1, CLRN1, RPE65, ABCA4, GUCA1, EYS, CYP4V2, GPR98 and ATXN7. Based on pedigree analysis, 20 patients were autosomal recessive retinitis pigmentosa, 3 patients were autosomal dominant retinitis pigmentosa and 1 patient was X linked retinitis pigmentosa. 3/7 patients with USH2A mutations were identified as Usher syndrome. ConclusionsUSHZA is the main disease-causing of sRP patients in Ningxia region. 83.3% of sRP in this cohort are autosomal recessive retinitis pigmentosa.