In the discovery stage, an Asian-specific coding variant rs2233580 (p.Arg192His) in PAX4, and two variants at the known loci, CDKN2B-AS1 and KCNQ1, were significantly associated with type 2 diabetes with exome-wide significance (p <sub>discovery</sub> < 6.45 × 10<sup>-7</sup>).
Collectively, these data suggest that the T2D-risk allele of rs11603334 could abrogate binding of a complex containing PAX6 and PAX4 and thus lead to increased promoter activity and ARAP1 expression in human pancreatic islets.
Interestingly, MAFA nuclear expression in both alpha and beta cells, and the percentage of alpha cells expressing PAX4 were found altered in a substantial proportion of patients with type 2 diabetes.
These results suggested that PAX4R192H polymorphism generated a protein with defect in transcriptional repressor activities on its target genes, which may lead to β-cell dysfunction associated with MODY and early onset-age of T2D as reported in our previous study.
Our study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.
In addition to these three major classes, we also review the available evidence on novel genes (CDK5 regulatory subunit associated protein 1-like 1 [CDKAL1], insulin-like growth factor 2 mRNA binding protein 2 [IGF2BP2], potassium voltage-gated channel, KQT-like subfamily, member 1 [KCNQ1], paired box 4 [PAX4] and neuronal differentiation 1 [NEUROD1] transcription factors, ataxia telangiectasia mutated [ATM], and serine racemase [SRR]) that have recently been proposed as possible modulators of therapeutic response in subjects with T2DM.
We screened PAX4 coding sequences in 46 MODY probands without mutation in known MODY genes and in 74 nondiabetic controls using PCR-single-stranded conformational polymorphism analysis followed by direct sequencing.
To clarify the role of PAX4Arg121Trp mutation on the development of type 2 diabetes mellitus, we try to determine the clinical phenotype in diabetic subjects with this mutation.