Novel triple missense mutations of GUCY2D gene in Japanesefamily with cone-rod dystrophy: Possible use of genotyping microarray

摘要

Purpose: To report a novel mutation in the GUCY2D gene in aJapanese family with autosomal dominant cone-rod dystrophy (adCORD), andto examine the possible use of arrayed primer extension (APEX)-basedgenotyping chip in detecting mutations.Methods: Genomic DNA was extracted from the peripheral blood offamily members with adCORD. It was PCR-amplified, fragmented, andhybridized to APEX-based genotyping microarrays on which knowndisease-associated sequence variations were arrayed for patients withearly-onset retinal dystrophy. All coding exons of the GUCY2D genewere directly sequenced. The PCR amplicon carrying a novel mutation wassubcloned, and each clone was sequenced.Results: Five single nucleotide polymorphisms in AIPL1,RPGRIP1, and GUCY2D were detected in the proband by microarrayscreening, and all were validated by direct sequencing. A novelheterozygous triple missense mutation of c.2540_2542delinsTCC(p.Gln847_Lys848delinsLeuGln amino acid substitutions) was found in boththe proband and his father, and the three nucleotide changes werelocated on the same chromosome. Electroretinography (ERGs) demonstrateda significant reduction in rod function and a complete absence of conefunction in both affected individuals.Conclusions: A novel heterozygous triple consecutive missensemutation in the GUCY2D gene has been linked to adCORD. Our studydemonstrates that the APEX-based gene screening can be used to identifysimultaneously disease-modifying sequence changes as well asdisease-causing mutations, once proper and comprehensive sites ofsequence variations of the disease are arrayed.