Q: One of my cousins has the Sickle Cell anaemia trait. He is married now. His wife is completely healthy. Now they are planning a child. We wanted to know, what are the chances that the child will carry the sickle cell trait?. Is there any way to know, whether the child will have this problem during pregnancy? If it is possible, let us know the details and in India, which are the places where this testing is available?

A:Sickle cell anaemia is an inherited disease of the blood, which is characterised by chronic anaemia and periodic episodes of pain. It is caused by an error (mutation) in the gene that controls haemoglobin synthesis. The mutation leads to synthesis of sickle haemoglobin (Hb S) instead of normal adult haemoglobin (Hb A) resulting in deformed (sickle-shaped) red blood cells. Two genes regulate haemoglobin synthesis. If an individual inherits copies of the defective gene from both parents, he/she will have sickle cell anaemia while individuals inheriting only one defective sickle haemoglobin gene from one parent will not have the disease, but will carry the sickle cell trait. Individuals with sickle cell trait generally have no symptoms, but they can pass the sickle haemoglobin gene on to their children. As your cousin has sickle cell disease and his wife is normal, the child will inherit one copy of the gene and will this have sickle cell trait. By sampling the amniotic fluid or tissue taken from the placenta, doctors can tell whether a fetus has sickle cell anaemia or sickle cell trait. This test can be done as early as the first trimester of pregnancy. This test is available in most major hospitals in the department of genetics/fetal medicine or gynaecology.