How is SCD inherited?
SCD is inherited in an autosomal recessive manner, meaning that a child must have changes in both copies of their hemoglobin gene to have SCD. Since each parent gave their child one copy of the gene, we know that both parents of a child with SCD have a change in one of their hemoglobin genes. Parents of children with SCD do not necessarily have SCD. A parent can have a single gene for abnormal hemoglobin, but the other gene in the pair is working correctly. In this case, a parent is called a carrier or said to have sickle cell trait. Carriers do not have SCD because the other gene of this pair is working correctly. When both parents are carriers, there is a 25% chance in each pregnancy for the child to have SCD. There is a 50% chance for the child to be a carrier, just like the parents. Finally, there is a 25% chance for the child to have two working genes.
