We have studied haplotype of ␤ S chromosome and ␣-globin gene status in 534 patients (255 adults and 279 children of whom 159 neonates) from Guadeloupe with various sickle cell-related conditions, namely SS (n = 298), SC (n = 170), S-␤-thal (n = 56), and other rare forms (n = 10). Haplotype data on ␤ S chromosomes confirm our previous observation that Benin type is the most prevalent (75%) ␤ S chromosome in Guadeloupe, in disagreement with the historical records. Comparison of the frequency of distribution of various ␤ S haplotypes between neonates and adults on the one hand and between SS and SC cases on the other shows that the current ␤ S haplotype distribution in this island is not distorted by haplotype-related differential survival. We also show that the frequency of ␣-thalassemia (−3.7 kb) in Guadeloupe is one of the highest recorded in this region involved in Atlantic slave trade and also failed to reveal any age-dependent increase in frequency. We conclude that the African component of Guadeloupe is distinct from that of Brazil and Cuba but is close to that of Jamaica. Am.

In a survey of the chromosomal background associated with the sickle cell gene in Guadeloupe, a French Caribbean island, we identified 37 unrelated patients with sickle cell disease (27 SS, nine SC, and one S-beta-thalassemia) of 477 unrelated sickle cell patients where the beta3 gene was linked to 20 different atypical haplotypes. These atypical chromosomes account for about 5% of the overall betaS chromosomes in this population. To investigate the origin of these atypical betaS haplotypes, we performed extensive typing of betaS and betaA chromosomes. Twenty-two different 5' subhaplotypes were identified among the betaS chromosomes. Fifteen of 20 different atypical haplotypes are likely to be the product of recombination by a single crossover around the <> 5' to the beta-globin gene, or between a major betaS haplotype and one of the betaS haplotypes present in the population. The remaining cases require genetic mechanisms (gene conversions, additional substitutions in a given haplotype) other than crossovers to generate these atypical haplotypes.

This is the first time a study has been undertaken on the HLA profile of the Martinican population, a population which is essentially the product of intermixture between African‐Negroes and French Caucasians. Two hundred and thirty‐eight non‐related subjects were typed for the A and B loci, 158 subjects for C locus and 128 for DR locus. After analysis of our parameters (antigen and gene frequencies, linkage disequili‐bria, etc.) and their comparison to those found in the Black and Caucasian control populations, we came to the conclusion that our racially‐mixed population is closer to the African‐Negro population than to the French Caucasian. A study of the average gene flow enabled us to evaluate the Caucasian contribution as being about 30%. This figure is subject to change inasmuch as racial intermixture continues. Socio‐cultural variables are assumed to play a minimal role, given the high rate of illegitimacy.