RECESSIVE INHERITANCE OF ADULT-TYPE LACTOSE MALABSORPTION

To study the genetic control of adult lactose malabsorption (L.M.) 252 relatives of 11 probands over 20 years old and 101 spouses of these relatives and probands were examined. A lactose-tolerance test with ethanol administration was used for diagnosis of L.M. General malabsorption was excluded by a glucose-galactose tolerance test with ethanol. Genetic analysis of family series gave strong support for the inheritance of adult L.M. by a single recessive autosomal gene. The number of affected persons observed in different relative groups of probands also supported this idea.