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


High levels of fetal haemoglobin (HbF) are protective in beta-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.

British journal of haematology