Sickle-cell disease in Brazzaville, Congo: genetical, hematological, biochemical and clinical aspects

Clinical, hematological and molecular features of 116 unrelated sickle-cell anemia patients from Brazzaville were investigated. The mean age of the patients was 9.4 +/- 5.3 years. 232 beta(s)-chromosomes were haplotyped and almost all sickle cell anemia patients (91%) were homozygous for the Bantu haplotype. All hematological indices were similar for males and females. Mean hemoglobin (Hb) concentration was 6.6 +/- 1.4 g/dl. Fetal Hb (HbF) levels were from 1 to 28%, with a mean of 8.8 +/- 5.8%. There was a curvilinear relationship between %HbF and age suggesting that HbF level had a selective effect on the survival of patients. This effect was sex dependent. The (-alpha(3.7)) gene frequency was 0.45 and was not affected by stratification for age. Hematological characteristics of patients with (-alpha/alphaalpha, -alpha/-alpha) and without (alphaalpha/alphaalpha) the -alpha(3.7) alpha-thal-2 deletion showed trends similar to those reported in Jamaican and US sickle cell anemia patients. Hyperbilirubinemia (>38 micromol/l) was common and high lactic dehydrogenase (LDH) concentrations were recorded. Bilirubin concentrations for males and females were similar whereas those for LDH concentration were not. Hepatomegaly and splenomegaly were common. Splenomegaly was strongly associated with the -alpha(3.7) alpha-thal-2 deletion. These clinical and hematological observations indicate a more severe form of hemolytic disease in Congolese SS patients.