Sickle Cell Genotype Checker

Understanding Sickle Cell Genotypes

Sickle cell disease is an inherited blood disorder caused by a mutation in the gene that produces haemoglobin. The genotype determines whether a person is normal (AA), a carrier (AS or AC), or has the disease (SS, SC, or CC). Understanding these genotypes and their inheritance patterns is crucial for family planning, especially in Africa where sickle cell prevalence is highest.

Genotype Combinations Explained

• AA (Normal): Both haemoglobin genes are normal. No sickle cell risk to pass on.
• AS (Sickle Cell Trait/Carrier): One normal gene, one sickle gene. Usually no symptoms but can pass the S gene to children. About 25-30% of Nigerians carry this trait.
• SS (Sickle Cell Disease): Both genes carry the sickle mutation. Causes sickle cell anaemia with chronic pain crises, organ damage, and reduced life expectancy if untreated.
• AC (Haemoglobin C Trait): One normal gene, one C gene. Generally mild or no symptoms.
• SC (Haemoglobin SC Disease): One sickle gene, one C gene. Milder than SS but still causes significant health issues.
• CC (Haemoglobin C Disease): Both genes carry the C mutation. Causes mild to moderate anaemia.

The Critical Importance of Genotype Testing

When two AS carriers have children together, each pregnancy has a 25% chance of producing a child with SS (sickle cell disease). This means that statistically, 1 in 4 children will have the disease, 2 in 4 will be carriers (AS), and 1 in 4 will be normal (AA). In Nigeria alone, approximately 150,000 babies are born with sickle cell disease each year — more than any other country in the world.

Pre-marital genotype testing has become standard practice in many Nigerian churches, hospitals, and cultural settings. While the decision to marry despite incompatible genotypes is deeply personal, informed decisions save lives. Genetic counselling is available at teaching hospitals across Africa.