Using a combination of homozygosity mapping, whole exome sequencing, and candidate gene screening, the group identified homozygous premature stop codon mutations in ALPK3 and, from immunohistological observations of heart tissue, suggest potential mechanisms for further exploration. Expression studies in mouse embryos and adult tissues have shown that Alpk3, also known as Midori, is expressed in the fetal heart as well as the adult heart and skeletal muscle, and it localizes to the nucleus where it may regulate transcription (5). Because Alpk3-deficient mice exhibit indistinct intercalated discs, Alpk3 may be necessary for their proper formation (4).