Archives of neurology · 2007
Asian origin for the worldwide-spread mutational event in Machado-Joseph disease.
СтатьяПоддержка исследования: вне правительства СШАНазвание и аннотация: Перевод в очереди
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Martins Sandra, Calafell Francesc, Gaspar Claudia, Wong Virginia C N, Silveira Isabel, Nicholson Garth A, Brunt Ewout R, Tranebjaerg Lisbeth, Stevanin Giovanni, Hsieh Mingli, Soong Bing-Wen, Loureiro Leal, Dürr Alexandra, Tsuji Shoji, Watanabe Mitsunori, Jardim Laura B, Giunti Paola, Riess Olaf, Ranum Laura P W, Brice Alexis, Rouleau Guy A, Coutinho Paula, Amorim António, Sequeiros Jorge
Аннотация
BACKGROUND: Machado-Joseph disease is the most frequent dominant ataxia worldwide. Despite its frequency and presence in many populations, only 2 founder mutations have been suggested to explain its current geographic distribution.
OBJECTIVES: To trace back in history the main mutational events in Machado-Joseph disease, we aimed to assess ancestral haplotypes and population backgrounds, to date the mutations, and to trace the routes and time of introduction of the founder haplotypes in different populations.
DESIGN, SETTING, AND PARTICIPANTS: We studied 264 families with Machado-Joseph disease from 20 different populations. Six intragenic single-nucleotide polymorphisms were used to determine ancestral mutational events; 4 flanking short tandem repeats were used to construct extended haplotypes and measure accumulation of genetic diversity over time within each lineage.
RESULTS: The worldwide-spread lineage, TTACAC, had its highest diversity in the Japanese population, where we identified the ancestral short tandem repeat-based haplotype. Accumulated variability suggested a postneolithic mutation, about 5774 +/- 1116 years old, with more recent introductions in North America, Germany, France, Portugal, and Brazil. As to the second mutational event, in the GTGGCA lineage, only 7 families (of 71 families) did not have Portuguese ancestry, although gene diversity was again smaller in Portuguese families (0.44) than in non-Portuguese families (0.93).
CONCLUSIONS: The worldwide-spread mutation may have first occurred in Asia and later been diffused throughout Europe, with a founder effect accounting for its high prevalence in Portugal; the other Machado-Joseph disease lineage is more recent, about 1416 +/- 434 years old, and its dispersion may be explained mainly by recent Portuguese emigration.
OBJECTIVES: To trace back in history the main mutational events in Machado-Joseph disease, we aimed to assess ancestral haplotypes and population backgrounds, to date the mutations, and to trace the routes and time of introduction of the founder haplotypes in different populations.
DESIGN, SETTING, AND PARTICIPANTS: We studied 264 families with Machado-Joseph disease from 20 different populations. Six intragenic single-nucleotide polymorphisms were used to determine ancestral mutational events; 4 flanking short tandem repeats were used to construct extended haplotypes and measure accumulation of genetic diversity over time within each lineage.
RESULTS: The worldwide-spread lineage, TTACAC, had its highest diversity in the Japanese population, where we identified the ancestral short tandem repeat-based haplotype. Accumulated variability suggested a postneolithic mutation, about 5774 +/- 1116 years old, with more recent introductions in North America, Germany, France, Portugal, and Brazil. As to the second mutational event, in the GTGGCA lineage, only 7 families (of 71 families) did not have Portuguese ancestry, although gene diversity was again smaller in Portuguese families (0.44) than in non-Portuguese families (0.93).
CONCLUSIONS: The worldwide-spread mutation may have first occurred in Asia and later been diffused throughout Europe, with a founder effect accounting for its high prevalence in Portugal; the other Machado-Joseph disease lineage is more recent, about 1416 +/- 434 years old, and its dispersion may be explained mainly by recent Portuguese emigration.