Studies of monogenic diabetes and type 1 diabetes have provided additional evidence in support of such intrauterine effects; an 8-year earlier age of diagnosis was observed for individuals inheriting a diabetes-causing mutation in HNF1A if this was inherited from their mother (who had diabetes while pregnant), than if inherited from their father [32]; and in a study of the offspring of parents with type 1 diabetes, those with affected mothers had poorer glucose tolerance and beta cell function than those with affected fathers [33]. The gene discussed is HNF1A; the disease is type 1 diabetes mellitus.