ALKBH3 and obesity due to melanocortin 4 receptor deficiency: For instance, there is evidence that ALKBH2 and ALKBH3 both function as DNA/RNA repair enzymes in vivo;17 ALKBH3 (or prostate cancer antigen (PCA)-1), in particular, is highly expressed in prostate cancer cells and is an attractive therapeutic target for prostate cancer.18 Recently, ALKBH5 is reported to be involved in spermatogenesis,11 while the FTO gene is found to be strongly linked to obesity in genome wide association studies.19–21 FTO provides the strongest link to the common form of obesity, to date.