Restriction mapping of β^S locus among tunisian sickle‐cell patients

Abstract

The very high frequency of the Benin haplotype in our study suggests that the β(S) mutation present in Tunisia may have originated from the Benin region and was brought to Tunisia along the slave trade routes. However, another atypical haplotype observed a new emergence in our population and could be considered as specific to Tunisian chromosome β(S).

Haplotype Map of Sickle Cell Anemia in Tunisia

“…Afterwards, the genomic relationship between the studied haplotypes was presented in a dendrogram according to PCA data (Figure 6) to verify previous observations and suggestions in order to confirm the accordance with our hypothesis that is published in our previous publication Imen et al [10]. …”

“…In Tunisia, sickle cell anemia haplotype was reported for the first time by Abbes et al [20] and later by Imen et al [10] describing six haplotypes: Benin is the most common, Bantu, and four atypical haplotypes [10]. …”

“…The following framework polymorphisms were investigated by polymerase chain reaction (PCR) and direct sequencing: (AT) x N 12 (AT) y repeat configurations within the 5′ HS2 region of β -LCR site [12, 13], (TG) n  (CG) m configurations in the IVSII region of fetal globin gene ( G γ and A γ ) [14], and (AT) x T y repeat configuration in the 5′ region of β -globin gene [15] (Figure 1), using respective couples of primers as summarized in Table 1. Tunisian β S RFLP haplotypes (HR) described previously in Imen et al have been used in this study [10]. …”

“…In the present study, we report the molecular investigations of four repeats sequences configurations (AT) x N 12 (AT) y motif within the 5′ HS2 region of β -LCR site, (TG) n (CG) m motif within IVSII region of fetal globin gene ( G γ and A γ ), and (AT) x T y motif within 5′ region of β -globin gene region of Tunisian β S chromosomes with five different RFLP-haplotypes (HR) described previously by Imen et al [10]. Besides, we have searched an association between these genetic markers in order to determine a specificity for the Tunisian β S chromosome.…”

Beta-Globin Gene Haplotypes Among Cameroonians and Review of the Global Distribution: Is There a Case for a Single Sickle Mutation Origin in Africa?

“…The Cameroon haplotype was then said to be restricted to a single ethnic group, the Eton of Central Cameroon (Lapoumeroulie et al, 1992), which is contrary to current data from Sudan (Elderdery et al, 2012;Mohammed et al, 2006). More recently, a specific atypical haplotype in Tunisia was considered by authors as specific to the Tunisian chromosome b(S) (Imen et al, 2011). In the case of the Cameroon and Tunisia, these specific haplotypes were likely generated by a variety of genetic mechanisms including (a) isolated nucleotide changes in one of the polymorphic restriction sites, (b) simple and double crossovers between two typical b(S) haplotypes, or much more frequently between a typical b(S) haplotype and a different b(A)-associated haplotype that was present in the population, and (c) gene conversions (Zago et al, 2000)-all of which have been observed at the beta-globin locus (Borg et al, 2009;Holloway et al, 2006;Liu et al, 2009;Neumann et al, 2010;Patrinos et al, 2005;Sankaran et al, 2011).…”