ARPKD is the most common heritable cystic renal disease occurring in infancy, with mutations of a single localized gene in an area in Chromosome 6 (PHKD1).[2] PHKD1 gene is expressed at high levels in fetal and adult kidneys and at lower levels in the liver and this corresponds to the principal sites of the disease. This evidence concerns the gene CALM1 and cystic kidney disease.