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 gene 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 two ethnically distinct populations. Subjects included 182 unrelated type 1 diabetes children and 201 control subjects from Ghana, West Africa. The Chinese study population consisted of 350 type 1 diabetic children and 420 healthy 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. CTLAC 49 (A→G) mutation conferred a risk 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 1 diabetes 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 1 diabetes in West Africans, but not in Chinese. On the other hand, the CTLA4 gene polymorphism at nucleotide position 49 significantly associated with type 1 diabetes in Chinese, but not in West Africans.