Fetal akinesia deformation sequence in a highly developed acardius twin.

We report a case of a holoacardius twin with extremely advanced development of the head, face, upper and lower limbs in the absence of all thoracic and upper abdominal viscera and associated with intestinal and anal atresia. The malformed fetus also had craniofacial abnormalities, hydrops, cystic hygroma of the neck, arthrogryposis and pterygia. The monozygous co-twin was found to be normal. The association of acardia with the typical characteristics of the fetal akinesia deformation sequence has not been previously described in the literature.