Am J Hum Genet 1990 Aug;47(2):302-7

Genetic epidemiology of hereditary tyrosinemia in Quebec and  Saguenay-Lac-St-Jean

De Braekeleer M, Larochelle J
SOREP, Universite du Quebec a Chicoutimi, Canada.

Abstract
Hereditary tyrosinemia type I is an autosomal recessive disorder that was
recognized in Saguenay-Lac-St-Jean (SLSJ) (Quebec) in 1967. Ninety-eight
tyrosinemic children, including some of the 113 children born in the SLSJ
region, have been screened by the Quebec Network of Genetic Medicine in the
whole province since 1970. The geographical distribution of the 98 children
screened showed the majority of them to have been born in the northeastern part
of Quebec. The prevalence at birth was estimated at 1/1,846 live borns, and the
carrier rate was estimated at 1/20 inhabitants in the SLSJ region. Three control
groups matched to the tyrosinemic obligate-carrier couples were generated using
the population register of the SLSJ region kept at SOREP. The mean coefficient
of inbreeding was only slightly elevated in the tyrosinemic group compared with
the control groups and was due to remote consanguinity. The mean kinship
coefficient was 2.3 times higher in the tyrosinemic group than in the control
groups. In the SLSJ region the places of origin of the tyrosinemic children and
their parents did not show a clustered nonuniform distribution. Endogamy was not
found to be higher in the tyrosinemic group than in the control groups. All
these results support both the hypothesis of a founder effect for tyrosinemia
and a high gene frequency in northeastern Quebec