A New Sickling Disorder Resulting from Interaction of the Genes for Haemoglobin S and α‐Thalassaemia

S ummary . A new abnormal haemoglobin syndrome is described resulting from homozygosity for the sickle‐cell gene in association with two α‐thalassaemia genes. This type of disorder is probably quite common in populations like those in Saudi Arabia where there is a relatively high frequency of both the sickle‐cell and α‐thalassaemia genes. In Saudi Arabia both sickle‐cell anaemia and α‐thalassaemia are associated with higher levels of foetal haemoglobin production than in other racial groups examined to date. This finding may account, at least in part, for the remarkable differences in the clinical manifestations of the sickling disorders in Saudi Arabia as compared with those observed in African populations.