Genetic epidemiology of autosomal recessive spastic ataxia of Charlevoix-Saguenay in northeastern Quebec.
Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a disorder that has an elevated frequency in Saguenay-Lac-St-Jean (SLSJ) and Charlevoix, two geographically isolated regions in the past of northeastern Quebec. The incidence at birth and the carrier rate in SLSJ were estimated at 1/1,932 liveborn infants and 1/22 inhabitants, respectively, for the period 1941-1985. The mean inbreeding coefficient was twice higher and the mean kinship coefficient 3 times higher among the ARSACS families than among control families. In the SLSJ region, the birth places of the ARSACS individuals and their parents did not show a clustered distribution. The genealogical reconstruction suggests that the high incidence of ARSACS in SLSJ and Charlevoix is likely to be the result of a founder effect. Because the disease is apparently unknown elsewhere in the world and a high proportion of French Canadians presently living in eastern Quebec have ancestors coming from Perche, a small region in France, it also suggests that a unique mutation accounts for most, if not all, of the ARSACS cases known in these regions.
De Braekeleer
M
M
Département des Sciences Humaines, Université du Québec à Chicoutimi, Canada.
Giasson
F
F
Mathieu
J
J
Roy
M
M
Bouchard
J P
JP
Morgan
K
K
D003241:Consanguinity; D005808:Genes, Recessive; D006579:Heterozygote; D006801:Humans; D015994:Incidence; D009128:Muscle Spasticity / Q000453:epidemiology* / Q000235:genetics*; D011792:Quebec / Q000453:epidemiology; D013132:Spinocerebellar Degenerations / Q000453:epidemiology* / Q000235:genetics*