Inversin (Inv or Nephrocystin-2) is encoded by the inversion of embryo turning (invs) gene [1]–[3] and was first discovered for its role during mammalian embryonic development in establishment of left-right asymmetry [4], which is reversed (situs inversus) in inv−/− mice with a homozygous deletion of exons 4–12, rendering only the first three exons transcribed [5]. The gene discussed is INVS; the disease is situs inversus.