Question

Name one autosomal dominant and one autosomal recessive Mendelian disorder in humans.

Answer 1

Mendelian disorder is a type of genetic disorder that occurs as a result of alteration in one gene. These genetic disorders are rare and may also occur non-inheritably. Autosomal dominant disorder means only one copy of an altered gene is needed to have the disorder while in autosomal recessive disorder two copies of altered genes are present.

Complete step by step answer:
According to Mendel’s’ law of inheritance, there are different types of disorders found in humans. Here we are going to discuss only two i.e. autosomal dominant and autosomal recessive.
-Autosomal dominant disorder: when changes occur in chromosome 1 through chromosome 22. A single abnormal gene from one parent can cause autosomal dominant disorder. For example- Huntington’s disease, Marfan syndrome etc. Huntington’s disease is a rare disease that can cause progressive breakdown of nerve cells. It is a psychiatric disorder directly affecting the mental health of a diseased person. It can cause movement (abnormal eye movement, involuntary jerking), cognitive (lack of awareness, laziness) and psychiatric disorder. It is most commonly first seen in the age of 30-40. If it occurs before 20 then the condition is known as juvenile Huntington’s disease. It leaves a serious impact that cannot be prevented by treatment.
-Autosomal recessive disorder: It is defined as a disease caused by involvement of both parents and alteration in two genes. For example- sickle cell anemia, colour blindness, Haemophilla etc.
Sickle-cell anemia is a disorder inherited by two parents. It occurs when glutamic acid in the sixth position of the beta-globin chain is replaced by valine. It is responsible for reducing the oxygen binding capacity of haemoglobin molecules.

Note: Autosomal dominant and autosomal recessive disorder both are inherited disorders caused by change in one or two genes. In autosomal dominant, involvement of a single parent can cause the disease while in autosomal recessive it is important for both the parents to cause alteration in two copies of genes.