Gene Conversion between Red and Defective Green Opsin Gene in Blue Cone Monochromacy

Blue cone monochromacy is an X-linked condition in which the function of both the red pigment gene (RCP) and the green pigment gene (GCP) is impaired. Blue cone monochromacy can be due to a red/green gene array rearrangement existing of a single red/green hybrid gene and an inactivating C203R point mutation in GCP. We describe here a family with blue cone monochromacy due to the presence of the C203R mutation in both RCP and GCP. The flanking sequences of the C203R mutation in exon 4 of RCP were characteristic for GCP, indicating that this mutation was transferred from GCP into RCP by gene conversion.