Haemoglobin genotype

Also written sickle cell trait or sickle cell disease without hyphens. AA means only normal adult haemoglobin. AS is sickle-cell trait and AC is haemoglobin C trait; both are usually healthy carrier states. SS and SC are forms of sickle-cell disease. Where both partners carry a variant, each pregnancy carries a risk that can be explained precisely by genetic counselling — the outcome is about inheritance probability, not a rule about who may marry whom.