A protein-protein interaction network analysis of a less stringent set of 86 MPHL-associated genes (P < 3 × 10−4 in the SKAT-O or the GenRisk analyses) detected enrichments with ectodermal dysplasia genes (FDR = 2.6 × 10−3, overlapping genes EDA2R, WNT10A, EDAR, HOXC13 and IFT122) and genes assigned to the gene ontology term hair follicle development (FDR = 0.014, overlapping genes WNT10A, EDAR, LAMA5, HOXC13, LGR4 and ALX4) (Supplementary Fig. 7). This evidence concerns the gene ALX4 and ectodermal dysplasia syndrome.