Dextrocardia with and without situs viscerum inversus in two sibs.

We described two sibs born to consanguineous Sicilian parents who died of severe congenital heart malformation. Both had dextrocardia; however, only the girl had situs viscerum inversus. At necropsy she was found to have a right spleen and right pulmonary isomerism (three lobes in each lung, as commonly found in the asplenia syndrome). This observation, together with other literature reports, suggest that isolated dextrocardia, situs viscerum inversus, and the asplenia-polysplenia complex may be different end results of a unique dysmorphogenetic process involving the embryonic midline.