Genetic basis of human left–right asymmetry disorders

Abstract

Humans and other vertebrates exhibit left–right (LR) asymmetric arrangement of the internal organs, and failure to establish normal LR asymmetry leads to internal laterality disorders, includingsitus inversusandheterotaxy.Situs inversusis complete mirror-imaged arrangement of the internal organs along LR axis, whereasheterotaxyis abnormal arrangement of the internal thoraco-abdominal organs across LR axis of the body, most of which are associated with complex cardiovascular malformations. Both disorders are genetically heterogeneous with reduced penetrance, presumably because of monogenic, polygenic or multifactorial causes. Research in genetics of LR asymmetry disorders has been extremely prolific over the past 17 years, and a series of loci and disease genes involved insitus inversusandheterotaxyhave been described. The review highlights the classification, chromosomal abnormalities, pathogenic genes and the possible mechanism of human LR asymmetry disorders.