In humans, glaucoma is inherited as an autosomal recessive trait (a), and Marfan syndrome, accompanied by an abnormality in the development of connective tissue, as an autosomal dominant trait (B). Genes are in different pairs of autosomes. One of the spouses suffers from glaucoma and had no ancestors with Marfan syndrome in the family, and the second is digeterozygous according to these signs. Determine the genotypes of the parents, the possible genotypes and phenotypes of children, the likelihood of having a healthy baby. Make a diagram of the solution to the problem. What is the law of heredity manifested in this case?
glaucoma is a recessive trait and appears only with homozygote, and Marfan syndrome is manifested with both hetero- and homozygote, but the trait is dominant, respectively, we determine the genotypes of the parents: one parent suffers from glaucoma – aa, but does not suffer from Marfan syndrome – bb, and the second parent, for both signs, is heterozygous – AaBb.
P: aabb x AaBb
G: AB x AB, AB, AB, AB
F1: AaBb – normal vision + Marfan syndrome
aabb – glaucoma
Aabb – normal vision, no Marfan syndrome – healthy child
aaBb – glaucoma + Marfan syndrome
Having drawn the Pennet lattice, you can see that the probability of giving birth to each child is the same – 25%, which means that the probability of having a healthy baby will be the same.
The genes of these traits are not linked, which means that the law of independent inheritance is manifested.