Defect in dorso-ventral patterning, asplenia, and conotruncus in a spontaneously aborted fetus.

We describe a very unusual combination, and previously unreported, of malformations in an 18-week, spontaneously aborted male fetus. The fetus had a reversed dorsoventral positioning of the head and upper limbs relative to the body axis with the head and both upper limbs directed dorsally, and an abrupt rotation of the vertebral bones at the level of CZ The fetus also had asplenia, single ventricle, and conotruncus. The fetus also had flexion deformities at the wrist, reduction deformity of the left second digit, anomalies in ossification of the bones of the left hand, and bilateral talipes calcaneovalgus. The major malformations in this fetus were all blastogenetic in origin and consisted of dorsoventral patterning defect involving structures cranial to C7, a laterality, and a septation defect of the ventricle and outflow tract of the heart. The defects are interpreted as being the result of abnormal coordination of the molecular signaling involved in dorsoventral axis formation and laterality of the limbs and trunk, and possibly also in cardiac septation.