Crohn's disease affecting three generations--case reports and genetic typing.

Crohn's disease, affecting three generations of a family is reported. An affected mother, an affected son, an unaffected daughter, and her affected child were evaluated by blood and HLA typing; no consistent differences among the family members were demonstrated. The significance of the HLA systems in relation to the genetic aspect of Crohn's disease is discussed. This report confirms the importance of heredity as one of several possible factors in the development of Crohn's disease.