Data on congenital total color-blindness were collected from the Japanese literature and through private communication, and tested for partial sex-linkage. Twenty sibships derived from consanguineous marriages, in which mode of relationship of the parents was fully known, were analyzed by using the direct method, and the crossover values 37.9-39.0% were found. Remaining 26 complete sibships were analyzed by using the indirect method, and a crossover value of 23.7% was obtained.
The higher recombination value derived from the direct method may possibly due to inaccurate information about paternal genotypes.