Association of a novel point mutation (C159G) of the CTLA4 gene with type 1 diabetes in West Africans but not in Chinese

Here, we report on the detection of a novel point mutation of the CTLA4 gen e at nucleotide position 159 (C -->G) leading to amino acid substitution at position 53 (I -->M), as well as its association with type 1 diabetes in t wo ethnically distinct populations. Subjects included 182 unrelated type 1 diabetes children and 201 control subjects from Ghana, West Africa. The Chi nese study population consisted of 350 type 1 diabetic children and 420 hea lthy control subjects from central China. Polymerase chain reaction-single- strand conformation polymorphism and sequence analysis were used to screen for polymorphisms in the CTLA4 gene. CTLA4 49 (A-G) mutation conferred a ri sk of type 1 diabetes in the Chinese children (odds ratio 1.78, 95% CI 1.58 -2.0), but not in the West African children (1.17, 0.84-1.64). On the other hand, the novel CTLA4 159 (C -->G) mutation conferred a risk of type I dia betes in the West African children (2.1, 1.54-2.86), but not in the Chinese type 1 diabetic children. The novel CTLA4 gene polymorphism at nucleotide position 159 significantly associated with type I diabetes in West Africans , but not in Chinese. On the other hand, the CTLA4 gene polymorphism at nuc leotide position 49 significantly associated with type I diabetes in Chines e, but not in West Africans.