Influence of alpha-thalassemia on cholelithiasis in SS patients with elevated Hb F

Chronic hemolysis, with consequent hyperbilirubinemia, predisposes SS patie nts to pigment gallstones. The other factors which influence the developmen t of stones in these patients have not been identified. We have carried out a combined prospective and retrospective study of SS patients in Kuwait an d specifically investigated the influence of coexistent alpha-thal trait on the prevalence of gallstones. A total of 45 patients (30 males, 15 females ) with ages ranging from 1 to 16 years (mean 7.2 +/- 3.1) were studied. Mos t were either homozygotes for the Saudi Arabia/India haplotype (86.7%) or c ompound heterozygotes for this and the Benin haplotype (11.1%). They were s creened for gallstones with ultrasonography. alpha-Globin genotypes were de termined using a combination of PCR and allele-specific oligonucleotide hyb ridization techniques to identify the common alpha-thalassemia alleles in t his population. Gallstones were detected in 7 (15.6%) patients (4 males, 3 females), whose mean age (10.5 +/- 5.5 years) was significantly higher than that (6.8 +/- 3.2 years) of those without stones (p < 0.01). The mean tota l Hb of the former (8.4 +/- 0.8 g/dl) was also significantly (p < 0.05) low er than in the latter(9.5 +/- 1.3 g/dl), while the difference in mean Hb F levels was not significant. None of the 4 alpha-thal homozygotes had gallst ones while 2 of 13 heterozygotes and 5 of the 23 patients without coexisten t a-thal had. The differences in these proportions are statistically signif icant (chi(2) = 20.4, p < 0.001). It therefore appears that coexistent alph a-thal decreases the chance of developing gallstones in Arab SS patients. T his may be related to less hemolysis in such patients as shown by their hig her mean Hb level.