Novel triple missense mutations of GUCY2D gene in Japanese family with cone-rod dystrophy: possible use of genotyping microarray.
OBJECTIVE
To report a novel mutation in the GUCY2D gene in a Japanese family with autosomal dominant cone-rod dystrophy (adCORD), and to examine the possible use of arrayed primer extension (APEX)-based genotyping chip in detecting mutations.


METHODS
Genomic DNA was extracted from the peripheral blood of family members with adCORD. It was PCR-amplified, fragmented, and hybridized to APEX-based genotyping microarrays on which known disease-associated sequence variations were arrayed for patients with early-onset retinal dystrophy. All coding exons of the GUCY2D gene were directly sequenced. The PCR amplicon carrying a novel mutation was subcloned, and each clone was sequenced.


RESULTS
Five single nucleotide polymorphisms in AIPL1, RPGRIP1, and GUCY2D were detected in the proband by microarray screening, and all were validated by direct sequencing. A novel heterozygous triple missense mutation of c.2540_2542delinsTCC (p.Gln847_Lys848delinsLeuGln amino acid substitutions) was found in both the proband and his father, and the three nucleotide changes were located on the same chromosome. Electroretinography (ERGs) demonstrated a significant reduction in rod function and a complete absence of cone function in both affected individuals.


CONCLUSIONS
A novel heterozygous triple consecutive missense mutation in the GUCY2D gene has been linked to adCORD. Our study demonstrates that the APEX-based gene screening can be used to identify simultaneously disease-modifying sequence changes as well as disease-causing mutations, once proper and comprehensive sites of sequence variations of the disease are arrayed.
Yoshida
Shigeo
S
Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. yosida@eye.med.kyushu-u.ac.jp
Yamaji
Yoko
Y
Yoshida
Ayako
A
Kuwahara
Rumi
R
Yamamoto
Ken
K
Kubata
Toshiaki
T
Ishibashi
Tatsuro
T
D000368:Aged; D044466:Asian People / Q000235:genetics*; D004596:Electroretinography; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D005838:Genotype; D006162:Guanylate Cyclase / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D020411:Oligonucleotide Array Sequence Analysis; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D011956:Receptors, Cell Surface / Q000235:genetics*; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology
D011956:Receptors, Cell Surface; C110715:guanylate cyclase 1; D006162:Guanylate Cyclase