During early development, the body has to establish top-bottom, front-back, and left-right relationships. Birth defects can result if the left-right position of organs is disturbed. These birth defects are sometimes called "heterotaxy". Malformations seen in heterotaxy include intestinal malrotation, altered spleen position and/or number, abnormal lobes of the lungs, and complex cardiac defects. Some cases run in families, but most of the time there is no family history. We don't know much about what causes these problems, but changes in genes that control the left-right relationships are probably important. Researchers at Baylor College of Medicine are conducting research on Heterotaxy syndrome and are recruiting children and adults with this condition and their close relatives. Participants are asked to provide a small blood or saliva sample at the time of enrollment, and a brief medical history and family history for heart diseases will be obtained. Your participation in this study will help us understand the genetic basis of this syndrome.