Morbidity, beta S haplotype and alpha-globin gene patterns among sickle cell anemia patients in Kuwait.

Abstract

Admission records of children with sickle cell anemia (SS), in the two main teaching hospitals in Kuwait, were reviewed for a 1-year period. The haplotypes of 92 beta s chromosomes (from 39 SS, 11 AS, 2 S beta-thalassemia [S beta-thal] and 1 SD individuals) were determined using an allele-specific oligonucleotide (ASO) hybridization technique, while the alpha-globin gene status of 27 SS and 33 AS individuals, i.e. 120 chromosomes, was determined with a combination of polymerase chain reaction and AS techniques. A vasooclusive crisis was the most common (60.0%) cause of hospitalization, followed by infections (20%). Hospital admissions were most common during the hottest month of the year (July). Few complications of the disease were seen among patients on follow-up; however, splenomegaly was present in 24.0%, hepatomegaly in 15.2%, gallstones in 15.2% and aseptic necrosis of the femoral head in 6.1%. Haplotype 31 (Saudi Arabia/India) is the most frequent in this community, being present in 80.4% of the chromosomes tested; Benin haplotype 19 was found in 12.0% and Bantu haplotype 20 in 6.5%. Hb F in the haplotype 31 homozygotes and heterozygotes ranged from 11.4 to 35.1% (mean 22.5 +/- 5.2%). The frequency of alpha-thal determinants in the study was 40.0%, the commonest being the -alpha 3.7-kb deletion (27.5%), the alpha 2 polyadenylation signal (AATAAA-> AATAAG) mutation (10.2%) and the IVS-I 5' end GAGGT-GAGG->GAGG pentanucleotide (5 nt) deletion (3.3%). SS patients with coexistent alpha-thal trait did not have severe recurrent infections and none had gallstones. The high frequencies of the Saudi Arabia/India beta s haplotype and alpha-thalassemia trait contribute to the mild nature of SS disease among Kuwaiti Arabs comparable to that in eastern Saudi Arabia.