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In Caucasians, the R506Q mutation in exon 10 of the factor V gene (FV Leiden) confers an increased risk of thromboembolism. We have scanned this region of the gene for possible mutations in 450 subjects from populations at risk for sickle cell disease (SCD). The R506Q mutation was absent in subjects from sub-Saharan Africa, whereas its allelic frequency was 2.5% in the West Indies. Only one other substitution with no functional consequences in vitro (R485K) was found (32.4% allelic frequency) in sub-Saharan Africa. Thus, we found no mutations in exon 10 of the FV gene constituting an additional risk factor for thrombosis in SCD in sub-Saharan Africa. This suggests that the putative selective advantage conferred by R506Q does not exist in these populations, unless R485K has functional consequences in vivo. If further suggests that R506Q in American Africans is of Caucasian origin. Our data are the first to document ethnic variations in the frequency of the R485K polymorphism.

Unlabelled: To evaluate the computed tomography (CT) findings of inflammatory lesions of the sternoclavicular joints (SCJ) in spondylarthropathies., Design and Patients: CT scans of the SCJs were obtained in 23 patients (group 1) with inflammatory SCJ lesions in spondylarthropathies. These scans were reviewed by four readers and compared with the CT scans of 23 matched controls (group 2). Each reader had to complete a 27-item grid., Results and Conclusion: In the 23 patients of group 1, the mean number of observed signs was 5.3 +/- 4.2 higher (P < 0.01) than in the group of 23 matched controls (2.4 +/- 1.6). Four signs were more frequently observed (P < 0.05) in group 1: surrounded subchondral clavicular erosions and cysts, surrounded subchondral sternal cysts and sternal bone sclerosis. A cyst and/or an erosion was associated with hyperostosis and/or bone sclerosis in 9 of 23 patients in group 1. This association was not observed in group 2; the difference was significant (P < 0.001). A cyst and/or an erosive lesion was observed 18 times in group 1 versus 11 times in group 2; the difference was significant (P < 0.05). Conversely, signs of degenerative lesions (osteophytes, subchondral sclerosis, unevenness of joint surface) were no more frequently observed in controls than in group 1. This study emphasizes the diagnostic value of CT, in particular in the identification of inflammatory lesions, even when pre-existing degenerative disease is present.