A COMPLETE SCREEN FOR MUTATIONS OF THE RHODOPSIN GENE IN A PANEL OF CHINESE PATIENTS WITH AUTOSOMAL DOMINANT RETINITIS PIGMENTOSA

Objective To evaluate the prevalence of rhodopsin (RHO) mutations and the genotype-phenotype relationships in Chinese patients with autosomal dominant retinitis pigmentosa (ADRP) by conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. Methods We have screened the five coding exons and splice sites of RHO gene in 27 probands who had no relativity from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using CSGE and direct DNA sequencing. Family members of some probands with disease-associated mutations were also genotyped to determine whether the RHO mutations segregated with retinitis pigmentosa (RP) in their families. Results Two RHO mutations, Pro347Leu and Pro327 (1-bp del), were identified separately in two families, thus the frequency of RHO mutations among this set of Chinese ADRP families is about 7.4% (2/27). Pro347Leu mutation was found in one ADRP proband as well as three her children who also had RP. She had relatively early onset at about 17 years. The only one child without this mutation had no symptom or sign of RP at age of 34. Pro327 (1-bp del) was identified in a late-onset ADRP patient, who appeared night blindness around 30 years old and in her fifties electroretinogram (ERG) has been flat in both scotopic and photopic phases. Family analysis showed that this mutation also existed in her younger dau-ghter and her elder sister, both of them also had RP. Three other family members were genotypically and phenotypically normal. Neither of the two mutations was detected in 100 normal controls.Conclusions The frequency of RHO mutations in Chinese patients was lower than that in Europe and North America. The phenotype of the patients with Pro347Leu corresponded to type 1 ADRP, with severe rod degeneration and some cone preservation later, while the phenotype of the patients carrying Pro327 (1-bp del) corresponded to type 2 ADRP, with a concomitant loss of rod and cone visual function. CSGE was found to be a sensitive, simple, and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.

Mutation Identification in A 5-Generation Pedigree with Autosomal Dominant Retinitis Pigmentosa

An extended 5-generation family has been investigated in which 32 of the 111 family members were diagnosed as having retinitis pigmentosa (RP) The proband was a 58-year old male in whom night-blindness was first observed in early childhood, with almost loss of vision by 52 years of age The symptoms observed in other family members included night-blindness, impaired vision and visual field loss Dementia, digital abnormalities, deaf-mutism and mental retardation were variously diagnosed in a number of individuals with RP The affected and unaffected family members were tested for mutations in a range of candidate genes The 8 exons of three candidate genes have been analyzed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing techniques A novel mutation was identified in the rhodopsin gene at codon 52 of exon 1 (TTC-TAC) that resulted in a substitution of Phe to Tyr

Gene mapping of autosomal dominant retinitis pigmentosa in a Chinese family

Background The autosomal dominant form of retinitis pigmentosa （ADRP） can be caused by mutations in 14 genes and further loci remains to be identified. This study was intended to identify mutations in a Chinese pedigree with ADRP. Methods A large Chinese family with retinitis pigmentosa was collected. The genetic analysis of the family suggested an autosomal dominant pattern. Microsatellite （STR） markers tightly linked to genes known to be responsible for ADRP were selected for linkage analysis. Exons along with adjacent splice junctions of PRPF31 were amplified by polymerase chain reaction （PCR） and screened by direct sequencing. Results The caused gene of ADRP was mapped to 19q13.4 between markers D19S572 and D19S877, with a maximum LOD score of 3.01 at marker D19S418 （recombination fraction=0）. Conclusion The affected gene linked to the 19q13.4 in a Chinese family with ADRP, which is different from other mutations at the same loci in other Chinese families.