Answer to Question #155206 in Genetics for Ashwani Kumar Gupta

Question

Blind girl, parents, brothers and sisters who were also blind, was married to a blind boy, a brother and sister who were also blind, and the other members of the family - mother, father, two sisters and a brother - sighted. From this marriage, 8 sighted children were born. Analyze the pedigree and name the reason for the birth of sighted children in blind parents.

Answer 1

This can be explained by such a phenomenon as genocopy.

Genocopies are similar phenotypes formed under the influence of different non-allelic genes. That is, these are the same changes in the phenotype, caused by the alleles of different genes, as well as occurring as a result of various gene interactions or violations of various stages of one biochemical process with the termination of synthesis. It manifests itself as the effect of certain mutations that copy the action of genes or their interaction.

The birth of children with normal vision in a marriage between two sick people with blindness indicates the genetic heterogeneity of this disease.