A genetic study of lactose digestion in Nigerian families.

The ability to digest orally administered lactose was determined in individuals representing a number of Nigerian ethnic groups. The data are mainly presented as family pedigrees. In those families where both parents were unable to digest lactose, all of the progeny were lactose nondigestors. If one parent, usually of Northern garopena origin or of the Fulani tribe, could digest lactose, then the progeny contained some or all individuals who were capable of digesting the disaccharide. There was no difference in the results when either the mother or the father was the lactose digestor. Ten families were studied where one parent was of Europena or Yoruba-European origin (lactose digestor) while the other was proper Yoruba 0lactose nondigestor). From these matings, there were 18 lactose digestors and 11 lactose nondigestors. We have concluded that the ability to digest lactose is transmitted as an autosomal dominant and represents the mutated gene or a polymorphism.