In one of these loci where SigNet and PoPS differ, both selected genes may be causal: at the locus where SigNet selects SLC4A3, responsible for a Mendelian form of short QT syndrome, PoPS selects DES (desmin), responsible for a Mendelian form of cardiomyopathy [3]. Here, SLC4A3 is linked to Familial short QT syndrome.