Deafness and Wilson’s disease (copper metabolism disorder) are recessive symptoms.

Deafness and Wilson’s disease (copper metabolism disorder) are recessive symptoms. A child with both anomalies was born from the marriage of a deaf man and a woman with Wilson’s disease. What is the probability of a healthy child being born in this family?

Deafness and Wilson’s disease are inherited as recessive traits. So, a – deafness, A – normal hearing; b – Wilson’s disease, B – normal copper metabolism. Considering that a child was born in the family with 2 diseases at once (his genotype is aavb), the parents are heterozygotes and have the following genotypes: father – aaBb and mother – Aabb.

Possible genotypes of children from these parents: AaBb – a healthy child, aaBb – a deaf child, Aabb – a child with Wilson’s disease, aabb – a child with both diseases. The probability of each of the 4 options is 25%.