Is haemoglobin G? Philadelphia linked to ?-thalassaemia?

Abstract
The question, “Is Hb Gα Philadelphia linked to α-thalassaemia?” was first posed because the abnormal haemoglobin is found in heterozygotes at a concentration greater than 25%, the proportion predicted from a 4 α-chain gene model. Globin chain biosynthesis was studied in a West Indian family in which one parent had β+ thalassaemia and the other was heterozygous for the Gα Philadelphia chain gene. The former had a globin chain production ratio α/β well above 1, while the latter had a ratio significantly less than 1. One child of the marriage had inherited the β+ thallassaemia from one parent and the Gα Philadelphia chain gene from the other and showed the typical picture of α/β-thalassaemia (α/β ratio slightly above normal). It is explained in the discussion that the evidence favours a close linkage of 2 α-chain genes.