The Kenya haemoglobin.

Abstract

Haemoglobin Kenya is (at present) a rare haemoglobin variant, found so far only in the Luo tribe in Kenya. It came to light by its chance association with the Hb S trait, a situation giving rise to an unexpectedly high level of Hb F, and about 17% of Hb Kenya. Occurring as a simple heterozygous mutant, Hb Kenya produces only about 6% of the variant; and in all cases it appears not to cause any disability. It arises by unequal crossing-over during meiosis, like Hb Lepore; non-α genes for Hb F (Gy, then Aγ) are contiguous with those for Hb A2 and Hb A (δ, then β), and the anomaly arises when the series on one chromosome is out of step with that on its partner in meiosis, one Aγ lying opposite to a β gene. Crossing-over between these produces a fusion Aγβ gene, and the loss of a 8 gene. An interesting result of this arises from the fact that Hb F persists in a hétérozygote for Hb Kenya. This means that his Gγ locus is still active, and therefore that the genetic mistake has removed a segment of DNA whose function is to " turn off "γ-chain production after birth. This mechanism was postulated years ago. Now that it has received a measure of confirmation, it may be that an isolated error in this DNA segment may explain " HPFH " genes causing simple hereditary persistence of Hb F. Other Luo subjects carrying Hb Kenya have recently been found by CLEGG et al. (Br. J. Haemat., 1974, v. 28, 141).