When a child carries a sickle cell trait

Last week, we tackled sickle cell, the disease; this week, I will look at the trait. Sickle cell trait refers to a condition in which a person has one abnormal allele of the haemoglobin beta gene, but does not display the severe symptoms of sickle cell disease that occurs in a person who has two copies of that allele. Normal haemoglobin is called haemoglobin A. People with sickle cell disease have only haemoglobin S, which turns normal, round red blood cells into abnormally curved (sickle) shapes.

Normally, a person inherits two copies of the gene that produces beta-globin, a protein needed to produce normal haemoglobin (ha emoglobin A, genotype AA).