Purpose: To determine X-linked red/green visual pigment gene arrays of a female proband with protan deficiency.
Methods: We examined a brother and both parents as well as the proband. Severity, severe or mild form, of color vision deficiency was estimated with either failure or passing of the Farnsworth Panel D-15 test. Diagnosis of either anomalous trichromacy or dichromacy was performed using a Nagel Type I anomaloscope. Genotypes of red/green visual pigment genes were determined by quantitative polymerase chain reaction-single strand conformation polymorphism analysis.
Results: Color vision tests revealed that the proband, her brother, her father, and her mother had protanomaly(mild form), protanopia, protanomaly(severe form), and normal color vision, respectively. In analysis of gene arrays, the brother had a red-green hybrid gene(R1G2, Ser 180) and three green visual pigment genes, while the father had a red-green hybrid gene(R4G5, Ser 180) and a green visual pigment gene.
Conclusions: It is impossible to directly determine each paternal or maternal X-linked red/green pigment gene array in the female proband. Molecular analysis of the family members revealed that the proband was a compound heterozygote for two R1 G2 and R4G5 hybrid genes encoding photopigments with different absorption maxima.