Analysis of FMR1 (CGG)(n) alleles and FRAXA microsatellite haplotypes in the population of Greenland: implications for the population of the New World from Asia

The fragile X syndrome is caused by the expansion of a polymorphic (CGG)(n) tract in the promoter region of the FMR1 gene, Apparently the incidence of fragile X syndrome is rare in the population of Greenland, In order to exa mine population-related factors involved in stability of the (CGG)(n) seque nce, DNA samples obtained randomly from the Greenlandic population were ana lysed for size and AGG interspersion pattern of the FMR1 (CGG)(n) region an d associated DXS548-FRAXAC1 haplotypes, In addition a large Greenland famil y with unstable transmission in the premutation range was analysed, The (CG G)(n) allele sizes in the Greenland population showed a narrow distribution similar to that reported for Asian populations, DNA sequencing of alleles with 36CGG repeats revealed an AGG(CGG)(6) insertion previously reported ex clusively in Asian populations and a high frequency of alleles with a (CGG) (10)AGG(CGG)(9)AGG(CGG)(9) : or (CGG)(9)AGG(CGG)(9)AGG(CGG)(6)AGG(CGG)(9) s equence pattern was found, Thus the data confirm the Asian origin of the Gr eenlandic (Eskimo) population and indicates that some (CGG)(n) alleles have remained stable for 15-30,000 years, since the population of the New World arrived from Asia via the Bering Strait.