More than one case has been observed on each autosome except 19 and the X chromosome. Published UPD cases seem to cluster on chromosomes 6, 7, 11, 14 and 15, which contain clusters of imprinted genes that cause clinical phenotypes (Figure S7). There are 1869 matUPD cases in total and 881 patUPD cases in total, suggesting that matUPD is about twice as common as patUPD.