A clinical entity that can present as variable anomalies of the caudal pole. It has been described in four siblings and their father's half-sister. The first sibling had aberrant umbilical cord vasculature with a single umbilical artery near the placental insertion. Two of the siblings showed full sirenomelia, one with a complex congenital heart defect. The fourth case had an imperforate anus and an excessively long umbilical cord. The half-sister had an imperforate anus, rectovaginal fistula and genitourinary anomalies. The syndrome appears to be expressed as a dominant trait with reduced penetrance and variable expressivity.