The progeny of the couple of which the husband was protanope and the wife deuteranope (Franceschetti, 1949) has been examined (3 generations) in 1986 and 1987. This couple had 4 children, of which 3 sons are deutan and 1 daughter, a double carrier, is phenotypically normal. This girl, in her turn and in exemplary fashion, has 3 children: 1 daughter, being simple carrier, is phenotypically normal, 1 son is protan and 1 son deutan. The study of the genomic DNA of 3 normal subjects reveals the presence of two genes responsible for green and one gene responsible for red; the genomic DNA of a protanomalous subject shows a modification of the gene for red, while that of two deuteranopes shows absence of genes responsible for green. The descent of the second couple in which the husband was deuteranope and the wife protanope (Franceschetti and Klein, 1956) is exclusively of female sex. Therefore it comprises only phenotypically normal persons.