Molecular analysis of the beta-globin gene cluster in the Niokholo Mandenka population reveals a recent origin of the beta(S) Senegal mutation

Am J Hum Genet. 2002 Jan;70(1):207-23. doi: 10.1086/338304. Epub 2001 Dec 6.


A large and ethnically well-defined Mandenka sample from eastern Senegal was analyzed for the polymorphism of the beta-globin gene cluster on chromosome 11. Five RFLP sites of the 5' region were investigated in 193 individuals revealing the presence of 10 different haplotypes. The frequency of the sickle-cell anemia causing mutation (beta(S)) in the Mandenka estimated from this sample is 11.7%. This mutation was found strictly associated with the single Senegal haplotype. Approximately 600 bp of the upstream region of the beta-globin gene were sequenced for a subset of 94 chromosomes, showing the presence of four transversions, five transitions, and a composite microsatellite polymorphism. The sequence of 22 beta(S) chromosomes was also identical to the previously defined Senegal haplotype, suggesting that this mutation is very recent. Monte Carlo simulations (allowing for a specific balancing selection model, a logistic growth of the population, and variable initial frequencies of the Senegal haplotype) were used to estimate the age of the beta(S) mutation. Resulting maximum-likelihood estimates are 45-70 generations (1,350-2,100 years) for very different demographic scenarios. Smallest confidence intervals (25-690 generations) are obtained under the hypothesis that the Mandenka population is large (N(e) >5,000) and stationary or that it has undergone a rapid demographic expansion to a current size of >5,000 reproducing individuals, which is quite likely in view of the great diversity found on beta(A) chromosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anemia, Sickle Cell / genetics*
  • Chromosomes, Human, Pair 11 / genetics
  • Computer Simulation
  • DNA Mutational Analysis
  • Ethnic Groups / genetics*
  • Evolution, Molecular*
  • Gene Frequency / genetics
  • Genetic Variation / genetics
  • Globins / genetics*
  • Haplotypes / genetics
  • Humans
  • Likelihood Functions
  • Microsatellite Repeats / genetics
  • Models, Genetic
  • Monte Carlo Method
  • Multigene Family / genetics*
  • Mutation / genetics*
  • Polymorphism, Restriction Fragment Length
  • Senegal / ethnology
  • Time Factors


  • Globins