The fragile X syndrome in Finland: demonstration of a founder effect by analysis of microsatellite haplotypes.
Microsatellite markers RS46 (DXS548) and FRAXAC2 flanking the fragile X mutation, an expansion of a (CGG)n repeat within the FMR-1 gene, were typed in 60 unrelated northern and eastern Finnish fragile X families and in a control population from the same geographical region. A significant difference was found in allelic and haplotypic distributions between the normal X and fragile X chromosomes. Evidence for a strong founder effect was detected, with the haplotype 196-153 being present on 80% of the fragile X chromosomes, but on only 8% of the normal X chromosomes. In addition to this major haplotype, four minor haplotypes were found on the fragile X chromosomes. These results suggest that the majority of present-day fragile X mutations in Finland may have a common initial ancestor, probably from the 16th century.
Department of Clinical Genetics, Oulu University Central Hospital, Finland.
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Haataja
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Väisänen
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Li
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Ryynänen
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Leisti
D004276:DNA, Satellite / Q000235:genetics*; D005260:Female; D005387:Finland; D018703:Founder Effect; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000208:ethnology / Q000235:genetics*; D005787:Gene Frequency; D005819:Genetic Markers; D006239:Haplotypes; D006801:Humans; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics; D010375:Pedigree; D016601:RNA-Binding Proteins; D014960:X Chromosome
D004276:DNA, Satellite; D051860:Fragile X Messenger Ribonucleoprotein 1; D005819:Genetic Markers; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human