Sickle cell disease is caused by a mutation in the hemoglobin gene, which is responsible for producing hemoglobin — the protein in red blood cells that carries oxygen throughout the body. In people with sickle cell disease, the hemoglobin molecules become rigid and take on a sickle shape, which causes the cells to block blood flow and lead to pain and other complications.

The condition is inherited in an autosomal recessive pattern, which means that a child must inherit two copies of the sickle cell gene—one from each parent—to develop sickle cell disease. If only one parent carries the sickle cell gene, the child will inherit the sickle cell trait but will not have the disease.

Carriers of the Sickle Cell Trait

People who carry one sickle cell gene and one normal gene are known as carriers or individuals with sickle cell trait. They do not experience the symptoms of sickle cell disease, but they can pass the sickle cell gene to their children. It is important for individuals with sickle cell trait to understand the implications of their genetic makeup, especially when it comes to family planning.

If both parents are carriers of the sickle cell trait, there is a 25% chance with each pregnancy that the child will inherit two sickle cell genes (and therefore have sickle cell disease), a 50% chance that the child will inherit one sickle cell gene and one normal gene (and be a carrier), and a 25% chance that the child will inherit two normal genes and not have sickle cell disease or carry the trait.

Genetic Testing and Screening

Genetic testing can help determine whether a person is a carrier of the sickle cell trait or has sickle cell disease. This type of testing is commonly done in newborns as part of routine screening programs in many countries. For adults, particularly if planning to start a family, genetic testing can provide important information about the risk of passing sickle cell disease or the sickle cell trait to their children.

In the UK, sickle cell screening is offered to newborns as part of the national screening program, which helps identify individuals with sickle cell disease or sickle cell trait early. For those who may be at risk of carrying the trait, preconception genetic testing or carrier screening can help provide information for family planning.

Impact of Genetics on Family Planning

Knowing whether both partners are carriers of the sickle cell trait is crucial when planning a family. If both parents carry the trait, there is a risk of having a child with sickle cell disease. In such cases, parents may consider options such as:

• Genetic counselling: Speaking with a genetic counsellor can help parents understand the risks and options available. A counsellor can provide advice on family planning, prenatal testing, and the potential impact of sickle cell disease on the child.
• Prenatal testing: Tests such as amniocentesis or chorionic villus sampling (CVS) can determine if a fetus has sickle cell disease. These tests can be done during pregnancy, typically between 10 and 12 weeks gestation, for couples who are carriers or who have a family history of the disease.
• Preimplantation genetic diagnosis (PGD): In some cases, couples undergoing in vitro fertilization (IVF) may choose PGD, a method where embryos are tested for sickle cell disease before being implanted in the uterus.

The Role of Genetics in Sickle Cell Disease

Understanding the genetic basis of sickle cell disease is critical for managing the condition and for supporting those living with it. Since sickle cell disease is inherited, it affects families and communities, and genetic education and counselling are essential for those at risk. By providing individuals with the knowledge of their genetic status, it’s possible to make informed decisions about healthcare, family planning, and managing the condition.

For those living with sickle cell disease, understanding the genetic origins of the condition can help in managing its impact on daily life and preventing complications. Regular health screenings, staying informed about advancements in treatment, and connecting with healthcare professionals can empower those affected by sickle cell disease to live well despite the challenges the condition may present.