Can a child inherit the gene for sickle cell anemia from just one parent or is it required from both parents?

Inheritance Pattern of Sickle Cell Disease

A child must inherit the gene for sickle cell anemia from both parents to develop the disease, as it follows an autosomal recessive inheritance pattern. 1

Genetic Basis of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive genetic disorder characterized by the presence of sickle hemoglobin (HbS) in red blood cells. This means:

• A person with sickle cell disease has inherited two abnormal hemoglobin genes, one from each parent 1
• When both parents carry one sickle cell gene (sickle cell trait), there is a 25% chance with each pregnancy that their child will have sickle cell disease 1
• If only one parent has the sickle cell gene, the child cannot develop sickle cell disease but may inherit sickle cell trait 1

Types of Sickle Cell Disease

The most common genotypes of sickle cell disease include:

• HbSS (sickle cell anemia): Inheritance of two sickle hemoglobin genes
• HbSC: Inheritance of one sickle hemoglobin gene and one hemoglobin C gene
• HbS/β-thalassemia: Inheritance of one sickle hemoglobin gene and one β-thalassemia gene 1, 2

Genetic Counseling Implications

For families with sickle cell disease or trait:

• Documentation of parental testing is essential for accurate genetic counseling 1
• Proper testing includes a complete blood count (CBC) and hemoglobinopathy testing 1
• Solubility testing (such as SickleDex) is not adequate for carrier testing as it will not identify individuals with hemoglobin C or β-thalassemia trait 1

Important Counseling Points for Families

• A child who has one parent with sickle cell disease will always inherit at least one sickle cell gene and will have at least sickle cell trait 1
• When both parents have sickle cell trait, there is a 25% chance with each pregnancy that their child will have sickle cell disease, a 50% chance the child will have sickle cell trait, and a 25% chance the child will have neither disease nor trait 1
• Prenatal diagnosis is available through amniocentesis, chorionic villous sampling, or preimplantation genetic diagnosis 1

Clinical Implications

Understanding the inheritance pattern is critical because:

• Early identification through newborn screening allows for prompt initiation of preventive care 2
• Children with SCD require specialized comprehensive medical care to decrease morbidity and mortality 1
• Genetic education should be provided to adolescents with SCD to help them understand reproductive risks 1

Common Pitfalls in Understanding SCD Inheritance

• Assuming that sickle cell disease can be inherited from just one parent (it cannot)
• Confusing sickle cell trait (carrier status) with sickle cell disease
• Using inadequate testing methods like solubility tests that miss important hemoglobin variants
• Failing to document parental testing when providing genetic counseling 1

The autosomal recessive inheritance pattern of sickle cell disease means that both parents must contribute a gene for the child to develop the disease, making genetic counseling and family planning crucial aspects of comprehensive care for individuals with SCD or sickle cell trait.