Aiming to better characterize CaM KMT and its potential contribution to the 2p21 deletion syndrome, we demonstrate alternative transcription from the CaM KMT exons outside the 2p21 deletion syndrome, but they are not likely to be translated, the accumulation of hypomethylated calmodulin in patients compared to normal controls suggesting that CaM KMT plays a pivotal role in calmodulin methylation and also that there are no compensatory mechanisms for CaM methylation in humans. This evidence concerns the gene CAMKMT and Down syndrome.