The TRPM subfamily of TRP channels includes TRPM6, which is a bifunctional protein comprising a TRP cation channel segment ion channel fused to a kinase domain with homology to the family of atypical alpha kinases []. The TRPM6 channel kinase plays a central role in systemic Mg(2+) homeostasis, and loss-of-function mutations in the human TRPM6 gene give rise to hypomagnesemia with secondary hypocalcemia (HSH) []. TRPM6 may have a role in neural tube closure during development, since mice with TRPM6 gene defects show neural tube defects and embryonic mortality [].