Ethnic differences in F cell levels in Jamaica: A potential tool for identifying new genetic loci controlling fetal haemoglobin

Abstract

High levels of fetal haemoglobin (HbF) are protective in β-haemoglobinopathies. The proportion of erythrocytes containing HbF (F-cells, FC) was measured in healthy adults of African and Caucasian ancestry to assess the feasibility of localizing genes for the FC trait using admixture mapping. Participants were Afro-Caribbean (AC) blood donors and residents of a rural enclave with a history of recent German admixture (Afro-German, AG) recruited in Jamaica, and Caucasian Europeans recruited in Jamaica and the UK. FC levels were significantly different between groups (P < 0·001); the geometric mean FC level in the AC sample (n = 176) was 3·75% [95% confidence interval (CI) 3·36-4·18], AG sample (n = 631) was 2·77% (95% CI 2·63-2·92), and among Caucasians (n = 1099) was 3·26% (95% CI 3·13-3·39). After adjustment for age, sex, haemoglobin electrophoresis pattern, and HBG2 genotype, FC levels in the AC group remained significantly different (P < 0·001) from those in the Caucasian and the AG group but the difference between the Caucasian and AG groups became non-significant (P = 0·46) despite substantial differences in average ancestry. The data confirm ethnic differences in FC levels and indicate the potential usefulness of these populations for admixture mapping of genes for FC levels. © 2008 Blackwell Publishing Ltd.