MODIFICATION IN THE FREQUENCY OF Hb C AND Hb S IN BURKINA FASO: AN INFLUENCE OF MIGRATORY FLUXES AND IMPROVEMENT OF PATIENT HEALTH CARE

Abstract

The incidence of hemoglobinopathies (Hb C and Hb S) is relatively high in West Africa. In order to calculate the gene frequency of these hemoglobinopathies, 6619 students from 23 local schools in Ouagadougou, Burkina Faso, West Africa, and 2582 individuals living in five villages near Ouagadougou, all situated in Savanna, were studied. As expected, the gene frequency in the city schools was 0.111 for the betaC gene and 0.051 for the betaS gene; in the five villages it was 0.122 for the betaC gene and 0.047 for the betaS gene. This data is somewhat different from that published in a previous study by Labie et al. [2] in the humid Savanna region, that showed a higher prevalence of betaC (0.14) than betaS (0.03), and is in contrast to data from the arid Sahel region that showed a higher prevalence of betaS (0.1) compared to betaC (0.05). The higher rate of betaS and lower rate of betaC in students in Ouagadougou, and in the individuals living in the five villages near Ouagadougou, suggest the possible influence of migratory fluxes of the betaS gene from the country region of Sahel. The dramatic increase in the prevalence of Hb SS patients, not reported in the study of Labie et al., [2] may be the result of reduced mortality due to environmental change. In addition, the improved health conditions of Hb SC and the increased life expectancy of Hb SS, may also have facilitated the increase of the betaS gene and the focus on secondary prevention for the control of correlated diseases.

Sickle Cell Disease in Africa

“…In Burkina Faso, Simpore et al 40 found 12 (0.13%) homozygotes among 9201 individuals screened during 1997–1999, consistent with a deficit in the numbers of people with SS of approximately 50% relative to the number expected based on HWE with frequencies of AS and SC of 8.1% and 1.5%, respectively. In western Kenya, Desai and colleagues 48 genotyped almost 1900 children younger than age 36 months during 1998–1999 and found frequencies of AS and SS of 22.0% and 0.6%, respectively.…”

“…For example, in a study conducted in Lusaka, Zambia, Athale and Chintu reported that the case-fatality rate among children with SS who were admitted to the University Teaching Hospital decreased from 18.6% in 1970 to 6.6% during 1987–1989 53 . Nevertheless, it is very likely that the majority of children with SS in rural Africa still die during childhood according to contemporary evidence from recent cross-sectional studies, including research papers from central Burkina Faso by Simpore et al, 40 the Nyanza province of Kenya by Desai et al, 48 the Kilifi district in coastal Kenya by Williams et al, 41 and from the Northern region of Ghana by Danquah et al 47 Although prospective cohort studies by Aidoo et al 43 and Kreuels et al 44 from western Kenya and southern Ghana, respectively, indicated little excess mortality among homozygotes, such data may not generalizable, given the likelihood that enrollment into prospective cohort studies will raise the probability of survival.…”

“…The impact of SC on child survival is less clear. Evidence of raised mortality has been reported in some studies, 39 but not in others 40 …”

Oxidative insult can induce malaria-protective trait of sickle and fetal erythrocytes

“…The HbAS and HbAC alleles are approximately six times more prevalent in malaria-endemic regions than the rarer HbCC and HbSC genotypes21. The respective carriers of HbAS and HbAC benefit the most from the presence of these polymorphisms since they are protected from the life-threatening complications of malaria, while having no or only mild symptoms.…”

Hemoglobina C em homozigose e interação com talassemia beta

“…1 A maioria das descrições é originária da África 13,14,15 e a prevalência tem sido influenciada, recentemente, por fluxos migratórios internos. 16 Uma comparação dos dados hematológicos e da esplenomegalia entre portadores homozigotos da Hb C e Cβ 0 de dados da literatura abrangendo vários trabalhos publicados entre 1967 e 1986, citado em Nagel e Steiberg, 1 apresentou valores da hemoglobina e hematócrito entre 10 g/dl a 15 g/dl e 30% a 45% respectivamente, VCM 60 a 90 fl, Hb Fetal 2% a 4%, reticulócitos 2% a 7% e moderada esplenomegalia para o homozigoto. Já na interação Cβ 0 , os valores de hemoglobina/ hematócrito variaram de 8 g/dl a 12 g/dl e 25% a 35%, VCM 55 fl a 70 fl, Hb F de 3% a 10%, reticulócitos de 5% a 20% e esplenomegalia acentuada.…”