Question

A couple, Jack and Jill, are both deaf, and each has one parent who also is deaf. Jack and Jill have eight children: six boys and two girls, four of whom (one daughter and three sons) are also deaf. Draw the pedigree for the family (see the correct pedigree in Fig. 8-10B; see the correct Punnett square in Fig. 8-10C) 1. Identify the specific pattern of inheritance (if any) indicated for this family? 2. Indicate what criteria the pedigree presents that support the correct pattern of inheritance for this health problem?

Answer 1

1. The family shows an equal distribution of trait between males and females. So this is not sex-linked inheritance. Both of the parents also have hearing loss which shows each of them has a copy of the altered gene of hearing loss. Thus the pattern of inheritance clearly shows an autosomal dominant pattern.

2. The pedigree shows that Jack and Jill have only a certain type of allele in their gene mutation. So the altered gene is not transmitted to every child and only the half of the son (3 out of 6)and half of the girl(1 out of 2) are affected with deafness.