October 1968

Studies of Lactose Intolerance in Families

Author Affiliations

Oklahoma City

From the Department of Medicine, University of Oklahoma Medical Center, Oklahoma City.

Arch Intern Med. 1968;122(4):315-317. doi:10.1001/archinte.1968.00300090025005

Lactose and glucose-galactose tolerance tests and dietary histories were obtained in 22 members of four families (two Negro and two white families). On the basis of flat lactose tolerance tests, 16 of the 22 individuals had a diagnosis of an isolated lactase deficiency which was further confirmed in two individuals by assays of intestinal disaccharidase activity. Lactose intolerance was present in more than one generation of each family; there was no sex predilection and a history of milk intolerance was more common in the older individuals with the defect. These data support a genetic factor in the etiology of an isolated lactase deficiency with late onset of symptoms.