A genome-wide study of 73 families with AP [28] reveals a strongest linkage for 8q24.21 and locus heterogeneity (locus 21.11 and genes GSDMC, FAM49B, ASAP1, and ADCY8) but with inconsistent findings; the authors concluded that AP is probably genetically heterogeneous. This evidence concerns the gene ADCY8 and alkaline phosphatase measurement.