Alpha thalassaemia and the haematology of normal Jamaican children.

Haematological indices were studied from birth to 9 years in a representative sample of 195 children with a normal haemoglobin (AA) genotype subdivided according to the number of alpha globin genes. These were 5 homozygotes for alpha-thalassaemia 2 (two-gene group), 60 heterozygotes for alpha-thalassaemia 2 (three-gene group), and 130 with a normal alpha globin gene complement (four-gene group). HbF and HbA2 showed no differences between the groups. Compared to the four-gene group, the three-gene group tended to have significantly lower levels of total haemoglobin, MCHC, MCV, and MCH, and higher levels of red cell count. These differences became apparent with increasing age in the order of MCV, RBC, MCHC, and total haemoglobin. The data suggested that haematological differences were more marked in the two-gene group but with the small numbers available, the differences were not significant.