One of the following is explained by digenetic inheritance

(B). Digenic inheritance explains the occurrence of retinitis pigmentosa (RP) in children of parents who each carry a mutation in a different RP-associated gene. Both parents have normal vision, as would be expected, but their offspring who are double heterozygotes-having inherited both mutations-develop RP. Digenic pedigrees can exhibit characteristics of both autosomal dominant (vertical transmission) and autosomal recessive inheritance (1 in 4 recurrence risk)