Infant mortality in myotonic dystrophy in Saguenay-Lac-St-Jean: a historical perspective

Infant mortality among children born to 373 individuals with myotonic dystrophy (MD) who lived in Saguenay-Lac-St-Jean during the period 1838 to the present time was analyzed using a case-control approach based on a population register. A statistically significant increase was found in the rate of deaths during the first week of life among children born to MD mothers (57.5%) compared to control mothers (34.8%) and MD fathers (39.1%) (p < 0.01). The stillbirth rate was not increased. The rate of mortality after the first week fell significantly in both MD and control groups during the period of observation. There was evidence of a slight selective disadvantage among this MD population.