CNNM2 function is in line with its expression in the DCT and brain, as heterozygous knockout (Cnnm2+/−) mice develop hypomagnesaemia due to decreased Mg2+ reabsorption, while a full knockout (Cnnm2−/−) is perinatally lethal and leads to brain malformations in a subgroup of mice16. The gene discussed is CNNM2; the disease is cerebral malformation.