Visceral heterotaxy-12 (HTX12) is an embryonic developmental disorder characterized by defects in the asymmetric positioning of visceral organs across the left-right axis, known as laterality defects. The phenotype is highly variable, ranging from complete organ reversal (situs inversus totalis) to selective misarrangement of organs (situs ambiguus) such as the liver, spleen, and pancreas. The disorder is often associated with dextrocardia or variable complex congenital heart defects. Early death may occur in the most severe cases (summary by Szenker-Ravi et al., 2022). For a discussion of the genetic heterogeneity of visceral heterotaxy, see HTX1 (306955).

Primary ciliary dyskinesia-52 (CILD52) is an autosomal recessive disorder characterized by laterality defects and mild respiratory symptoms due to subtle ciliary beating defects (summary by Leslie et al., 2022). For a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).