Question

Of nearly 200 forms of hereditary deafness, 132 are autosomal recessive, 64 autosomal dominant, and 4 X-linked recessive. Hereditary deafness is therefore genetically:

a) Homogeneous
b) Heterogeneous
c) Isolated
d) Homozygous

Answer 1

Hereditary deafness is classified as genetically heterogeneous because it can be caused by a variety of genetic variations, including autosomal recessive, autosomal dominant, and X-linked recessive forms. The correct option for the question 'Hereditary deafness is therefore genetically:' is b) Heterogeneous.

Step-by-step explanation:

Hereditary deafness is genetically heterogeneous due to the presence of different forms of genetic variations leading to this condition. With a total of nearly 200 forms, 132 are autosomal recessive, 64 are autosomal dominant, and 4 are X-linked recessive.

For autosomal recessive forms, individuals with hereditary deafness are homozygous recessive for the trait. Conversely, in autosomal dominant forms, affected individuals have at least one dominant allele and may be either homozygous dominant or heterozygous. X-linked recessive conditions tend to affect males more than females due to their single X chromosome. Autosomal recessive genetic disorders like cystic fibrosis require both copies of the gene to be affected for the trait to be expressed, meaning that carriers, who are heterozygous, will not exhibit symptoms. Autosomal dominant conditions, however, can manifest with just one copy of the affected gene. Examples of such conditions include neurofibromatosis and Huntington's disease. The correct option for the question 'Hereditary deafness is therefore genetically:' is b) Heterogeneous.