Compound heterozygosity for the Xeroderma pigmentosum complementation group A gene associated with a mild phenotype.
We describe a case of a 7-year-old boy diagnosed as xeroderma pigmentosum complementation group A (XPA). Severe photosensitivity developed at 5 months after birth, and at a visit to our hospital at the age of five years, multiple brownish freckles were present on the face. XPA complementing (XPAC) gene compensated the ability of DNA repair after UV-irradiation of the fibroblasts. PCR-RFLP and DNA sequencing analyses revealed compound heterozygosity for a splicing mutation (IV3 -1G => C) at the splicing acceptor site of intron 3 and a nonsense mutation (Arg228 => stop) in exon 6. The former mutation can be detected by a restriction enzyme Alw NI and the latter detected by Hph I. Neither obvious neurological symptoms nor malignant skin tumors were noted. This genotype is associated with milder clinical symptoms than homozygosity for the IV3 -1G => C mutation.
Negishi
Izumi
I
Department of Dermatology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan. inegishi@showa.gunma-u.ac.jp
Kato
Go
G
Moriwaki
Shinichi
S
Ishikawa
Osamu
O
D001483:Base Sequence; D002648:Child; D004252:DNA Mutational Analysis; D005347:Fibroblasts / Q000528:radiation effects; D005816:Genetic Complementation Test; D020022:Genetic Predisposition to Disease; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010641:Phenotype; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011379:Prognosis; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014983:Xeroderma Pigmentosum / Q000175:diagnosis* / Q000235:genetics*