α Thalassaemia in two Spanish families

Two Spanish families with α thalassaemia, including 4 individuals with Hb H disease, are described. DNA mapping shows that, in addition to the common α thalassaemia determinant (‐α3.7), a different and previously unreported allele is present in each family. In one, there is a deletion of 10.5–12 kb of DNA including both α genes (‐SPAN). in the other, a deletion of more than 100 kb has removed the entire α globin gene complex (‐BR).