CD4 and type 1 diabetes mellitus: Alternatively, it may be that other genes in the region, which have not been as well studied as IL2RA, are also causal for T1D, either directly or through interaction with IL2RA. For example, PFKFB3, an inducible 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase isoform, allows rapid responses to energy requirements and insufficiency can lead to apoptosis and an inability to undergo autophagy in CD4+ T cells in RA [29].