Heterozygous mutations in the PAX4 gene have been reported in MODY type 9 (OMIM: 612225), type 2 diabetes mellitus (OMIM: 125853) with autosomal dominant inheritance, and in diabetes with a predisposition to ketosis (OMIM: 612227), with both autosomal dominant and autosomal recessive inheritance patterns. Here, PAX4 is linked to type 2 diabetes mellitus.