Frequency of sickle cell genotype among the Yorubas in Lagos: implications for the level of awareness and genetic counseling for sickle cell disease in Nigeria.

The frequency of sickle cell genotype (HbSHbS) among the Yorubas living in Lagos, Nigeria, was determined. Seven hundred fifteen (715) subjects of different age groups took part in the study after filling consent forms and questionnaires. The haemoglobin genotype of each subject was determined by the usual electophoretic method from blood sample (3.0 ml) obtained from the antecubital vein. Normal and sickle cell haemoglobin genotypes were detected in subjects within the age group 1-50 years such that 366 (73.1%) had HbAHbA genotype, 123(24.5%) had HbAHbS, while 12 (2.4%) had HbSHbS giving genotypic frequencies that were not significantly different from Hardy-Weinberg expectations (P > 0.05). More than half (58.3%) of the subjects with the HbSHbS were in the 11-30 years age group. The results of this study showed that there is need for more awareness campaign and proper genetic counselling about sickle cell disease in Nigeria. This is particularly so for adolescents since they are likely to constitute the majority of intending couples and, therefore, those that will produce genes that will make up the gene pool for future generations. In situations where pregnancy had occurred before the actual marriage (as is sometimes the case), the importance of proper prenatal diagnosis and genetic counselling for sickle cell disorder cannot be overemphasized.