Q.Mention any two autosomal genetic disorders with their symptoms.

Two common autosomal genetic disorders are Sickle Cell Anaemia and Thalassemia — both are autosomal recessive disorders affecting the haemoglobin molecule.

Sickle Cell Anaemia results from a point mutation in the beta-globin gene that substitutes valine for glutamic acid. Its symptoms include chronic anaemia, painful sickle-cell crises caused by blocked blood vessels, and frequent infections. …

Mendelian genetics, as taught in your NCERT textbook, deals with the inheritance of traits controlled by single genes. When a mutation occurs in a gene located on one of the 22 pairs of autosomes (chromosomes that are not the X or Y sex chromosomes), the resulting condition is called an autosomal genetic disorder. These disorders can be dominant (only one faulty copy of the gene is needed to cause the disease) or recessive (two faulty copies are needed). Let's look at two such disorders that are specifically mentioned in your syllabus.

Sickle Cell Anaemia is an autosomal recessive disorder. The mutation is in the gene that codes for the beta-globin chain of haemoglobin. This single change causes the haemoglobin molecule to become defective. Under low oxygen conditions, the red blood cells change from their normal disc shape to a rigid, sickle-like shape. These sickle cells are fragile and break down easily, leading to a shortage of red blood cells (anaemia). The symptoms are directly linked to this shape change and cell destruction.

The key symptoms include:

• Chronic Anaemia: Because the sickle cells are destroyed rapidly, the body cannot maintain a healthy number of red blood cells, leading to fatigue, weakness, and paleness.
• Pain Crises: The rigid, sickle-shaped cells can block small blood vessels, causing severe pain in the chest, abdomen, joints, and bones. These episodes can last for hours to days.
• Swelling of Hands and Feet: Blockage of blood flow in the extremities can cause painful swelling, known as dactylitis.
• Frequent Infections: The spleen, which helps fight infections, is often damaged by the sickle cells, making individuals more vulnerable to infections, especially from bacteria like Pneumococcus.
• Delayed Growth: The chronic shortage of oxygen and nutrients can slow growth and development in children.

Thalassemia is another autosomal recessive disorder, also affecting haemoglobin production. However, unlike sickle cell anaemia which produces a faulty haemoglobin, thalassemia is characterised by a reduced or absent synthesis of one of the globin chains. This leads to an imbalance in the production of alpha and beta globin chains, resulting in the formation of abnormal haemoglobin molecules and the destruction of red blood cell precursors in the bone marrow.

The symptoms vary depending on the severity of the condition (major, intermedia, or minor). For the severe form (Thalassemia Major), symptoms include: …

A useful check when picking examples for 'autosomal genetic disorder' questions is to sort disorders into two mental bins: single-gene (Mendelian) disorders on an autosome — such as sickle-cell anaemia and thalassemia, both autosomal recessive — versus disorders caused by an abnormal chromosome number (aneuploidy), like Down syndrome. Both bins can technically be 'autosomal', but the chapter's own worked examples for thi …