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November 23, 2003
HD Prevalence By Population
The prevalence is between 3 and 7 per 100,000 in populations of western European descent. HD appears less common in Japan, China, Finland, and African blacks [Hayden et al 1980]. The frequency of HD in Japan has been estimated at between 0.1 and 0.38 per 100,000. The prevalence of HD exceeds 15 per 100,000 in some populations that are mostly of western European origin [Hayden et al 1981 , Folstein 1989 , Harper 1996].
The uneven distribution of HD is at least partially explained by the distribution of predisposing alleles and haplotypes in the normal population of these ethnic groups [Kremer et al 1994 , Squitieri et al 1994 , Almqvist et al 1995 , Watkins et al 1995]. The most common alleles in all populations contain 15 to 20 CAG repeats; in western European populations, the distribution is skewed towards longer alleles within the normal range, whereas these longer alleles are less common in African and Asian populations [Squitieri et al 1994 , Watkins et al 1995 , Rubinsztein et al 1996]. This suggests that the expanded alleles in the disease range arise from long normal alleles, which are more prevalent in western European populations.
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Children's Health System and University of Washington, Seattle
Posted by Dave at November 23, 2003 08:05 AM
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