Acute clinical events in 299 homozygous sickle cell patients living in France

A subset of 299 patients with homozygous sickle cell anaemia. enrolled in t he cohort of the French Study Group on sickle cell disease (SCD), was inves tigated in this study. The majority of patients were children (mean age 10. 1 +/- 5.8 yr) of first generation immigrants from Western and Central Afric a, the others originated from the French West Indies (20.2%). We report the frequency of the main clinical events (mean follow-up 4.2 +/- 2.2 yr). The prevalence of meningitis-septicaemia and osteomyelitis was, respectively, 11.4% and 12% acute chest syndrome was observed in 134 patients (44.8%). Tw enty patients (6.7%) developed stroke with peak prevalence at 10-15 yr of a ge. One hundred and seventy-two patients (58%) suffered from one or more pa inful sickle cell crises, while the others (42.5%) never suffered from pain . The overall frequency of acute anaemic episodes was 50.5%, (acute aplasti c anaemia 46% acute splenic sequestration 26%). A group of 27 patients were asymptomatic (follow-up >3 yr). Epistatic mechanisms influencing SCD were studied. Coinherited alpha-thalas semia strongly reduced the risk of stroke (p<0.001) and increased that of p ainful crises (p < 0.02). There was a low prevalence of Senegal and Bantu ( CAR) beta(s)-chromosomes in patients with meningitis (p<0.04) and osteomyel itis (p<0.03). Prevalence of Senegal beta(s)-chromosomes was lower in the a symptomatic group of 27 patients (p <0.02). The patients come from a popula tion of unmixed immigrants in whom the beta-globin gene haplotype strongly reflects the geographic origin and identifies subgroups with a homogenous g enetic background. Thus the observed effects might result more from differe nces in as yet unidentified determinants in the genetic background than fro m the direct linkage with differences in the beta-globin gene locus.