IRX5 and Kabuki syndrome: Significant downregulation of all biallelic LOE genes was confirmed using quantitative PCR (qPCR; Supplementary Table 10), although this analysis identified only an approximately threefold reduction in FRG1B and IRX5. Biallelic LOE of PHKG1 and IRX5 occurred in two subjects both with Kabuki syndrome (MIM147920 (ref. 7)), caused by damaging de novo KMT2D mutations4.