Background: The gene responsible for the xeroderma pigmentosum (XP) group A gene was recently identified and isolated. Preliminary study with fibroblasts from patients with XP group A revealed that most of the Japanese patients with XP group A have a point mutation at the 3' splice acceptor site of intron 3. This mutation site in the XP group A-complementing gene can be recognized by a restriction enzyme, AlwNI. This article describes the usefulness of the polymerase chain reaction diagnosis on XP group A.
Observations: We tried a polymerase chain reaction diagnosis on genomic DNA from a sporadic case of XP group A and this child's parents. AlwNI restriction fragment length polymorphism of the polymerase chain reaction product showed three bands for his father's and mother's DNA, one corresponding to normal and two corresponding to a point-mutated gene, respectively. A DNA sample from our patient showed two fragments indicating that only he has the mutated gene.
Conclusions: This study demonstrated that we can know that this patient has group A XP without a complementation test that needs a lot of time. Moreover, our study revealed that we can detect the hidden mutated XP group A-complementing gene in the pedigree in which there is no patient with XP. Furthermore, it may be available soon for prenatal diagnosis.