Genotype and clinical phenotype analysis in patients with retinitis pigmentosa and cone rod dystrophy

Abstract

Objective To observe the gene mutation and clinical phenotype of patients with retinitis pigmentosa (RP) and cone rod dystrophy (CORD). Methods Thirty-seven patients with RP and 6 patients with CORD and 95 family members were enrolled in the study. The patient’s medical history and family history were collected. All the patients and family members received complete ophthalmic examinations to determine the phenotype, including best corrected visual acuity, slit lamp microscope, indirect ophthalmoscopy, color fundus photography, optical coherence tomography, full-field electroretinogram, and fluorescein fundus angiography. DNA was abstracted from patients and family members. Using target region capture sequencing combined with next-generation sequencing to screen the 232 candidate pathogenic mutations. Polymerase chain reaction and direct sequencing were used to confirm the pathogenic pathogenic mutations and Co-segregation is performed among members in the family to determine pathogenic mutation sites. The relationship between genotype and clinical phenotype of RP and CORD was analyzed. Results Of the 37 patients with RP, 13 were from 6 families, including 4 families with autosomal dominant inheritance, 2 families with autosomal recessive inheritance, and 3 in 6 families were detected pathogenic gene mutations. 24 cases were scattered RP. Six patients with CORD were from four families, all of which were autosomal recessive. Of the 43 patients, 21 patients were detected the pathogenic gene mutation, and the positive rate was 48.8%. Among them, 15 patients with RP were detected 10 pathogenic gene mutations including USH2A, RP1, MYO7A, C8orf37, RPGR, SNRNP200, CRX, PRPF31, C2orf71, IMPDH1, and the clinical phenotype included 10 typical RP, 2 cases of RPSP, 3 cases of Usher syndrome type 2 and 6 cases of CORD patients were all detected pathogenic gene mutations, including 2 cases of ABCA4, 2 mutations of RIMS1 gene, 1 case of CLN3 gene mutation, and 1 case of CRB1 and RPGR double gene mutation. Conclusions RP and CORD are clinically diverse in genotype and clinically phenotypically similar. For patients with early RP and CORD, clinical phenotype combined with genetic analysis is required to determine the diagnosis of RP and CORD. Key words: Retinal diseases/genetics; Retinitis pigmentosa/genetics; DNA mutational analysis; Phenotype