Background: Although mutations of the CHM gene have been reported in the Caucasian patients with choroideremia, there have been no such reports in non-Caucasian patients. We analyzed the CHM gene in a Japanese patient with choroideremia associated with pinealoma.
Methods: The method for screening was a nonradioisotopic modification of single-strand conformation polymorphism (SSCP) analysis. The PCR products from the patient and the carrier were screened and directly sequenced using an automated DNA sequencer. The PCR product of the carrier was also subcloned into a vector and the subcloned products were sequenced.
Results: SSCP analysis showed an identical abnormal band shift in the patient and the carrier. Direct sequence analysis showed a hemizygous A to CC mutation at nucleotide 1608 of the CHM gene in the patient, suspected to result in the absence or truncation of the predicted CHM protein. The sequence using both the PCR product and the subcloned DNA of the carrier showed both wild-type and mutant bands indicating a heterozygote.
Conclusion: The hemizygous mutation was detected in a patient and the heterozygous pattern in his mother, the carrier, suggesting that this mutation caused the disease.