Gene frequency and type of colour blindness in Ethiopians.

All 954 boys and 1064 girls attending two schools in north-western Ethiopia were tested in February 1988 for colour blindness using the Ishihara plates. A total of 40 colour blinds (4.2%) were found among males and 2 (0.2%) among females. There were 31 (3.2%) deutans and 9 (0.9%) protans among males. Both female colour blinds were deutans. This study confirms a previous observation on the gene frequency of colour blindness in this population. For the first time it also provides information on the frequency of this polymorphism in female Ethiopians, as well as types of red-green defects.