OBJECTIVETo investigate the mutation spectrum of phosphodiesterase beta subunit (PDE6B) gene and incidence in Chinese retinitis pigmentosa (RP) patients.

METHODSGenomic DNA was extracted from the blood samples of 38 patients from 35 autosomal recessive retinitis pigmentosa (ARRP) families and 55 sporadic cases. The mutation of the PDE6B gene was detected using PCR-SSCP, and the amplified PCR product of abnormal bands was sequenced.

RESULTSWithin intron 10 of PDE6B gene, a mutation was found in an ARRP family, a G --> A transition at 19th base upstream 5'-end of exon 11. A novel complex heterozygous variant of PDE6B gene in a sporadic case, a T to C transition in codon 323 resulting in the substitution of Gly by Ser and two bp(TG) inserted between the 27th-28th bp upstream of the 5'-end of exon 10 were both present in the same isolate RP. But they were not found in 100 unrelated normal individuals. A sporadic RP was found carrying a sequence variant of PDE6B gene, a G to C transversion in intron 18, the 15th base adjacent to the 3'end of exon 18. Another isolate RP was found to have 2 bp inserted between 31st and 32nd base upstream 5'end of exon 4 (in intron 3) of PDE6B gene.

CONCLUSIONThere is a complex heterozygous mutation of PDE6B gene responsible for a sporadic RP patient in China. Several DNA variants were found in intron of PDE6B gene in the national population.

Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; Cyclic Nucleotide Phosphodiesterases, Type 6 ; genetics ; DNA Mutational Analysis ; Exons ; Female ; Humans ; Male ; Molecular Sequence Data ; Mutation ; Polymerase Chain Reaction ; Polymorphism, Single-Stranded Conformational ; Retinitis Pigmentosa ; genetics

PURPOSE: Sildenafil citrate, is an oral tablet demonstrating efficacy for maintaining an erection in males with erectile dysfunction by inhibiting phosphodiesterase type 5 (PDE5). In the present study, we report 1 case of a transient color anomaly with visual field defect after an overdose of sildenafil citrate. CASE SUMMARY: One patient, a 39-year-old female, with no significant medical history other than previous major depressive disorder, visited an outpatient department due to the visual field defect that began after taking 30 tablets of sildenafil citrate (50 mg) 3 days earlier. A number of ophthalmologic tests were administered including visual acuity test, color vision test, fundus photography and the measurement of retinal structure with optical coherent tomography and her condition was monitored. The best corrected visual acuity was 1.0 in both right and left eyes in her first visit. The color anomaly and a central scotoma of both eyes were detected in the visual field test, while significant signs were not observed after evaluation using optical coherent tomography and fundus photography. After 5 weeks, the visual acuity was not affected, the color anomaly symptom disappeared and the focal visual field defect was present although improved. CONCLUSIONS: Transient color anomaly and persistent central scotoma caused by an overdose ingestion of sildenafil has not been reported in Korea, The related mechanisms may involve the inhibition of PDE5 on ganglion cells and bipolar cells in the retina and interruption of phosphodiesterase type 6 (PDE6) function in both rods and cones.
Adult ; Citric Acid* ; Color Vision ; Cyclic Nucleotide Phosphodiesterases, Type 6 ; Depressive Disorder, Major ; Eating ; Erectile Dysfunction ; Female ; Ganglion Cysts ; Humans ; Korea ; Male ; Outpatients ; Photography ; Photoreceptor Cells, Vertebrate ; Retina ; Retinaldehyde ; Scotoma ; Tablets ; Visual Acuity ; Visual Field Tests ; Visual Fields* ; Sildenafil Citrate