Visceral heterotaxy-6 (HTX6) is characterized by dextrocardia with or without accompanying complex cardiovascular defects, as well as variable manifestations of visceral heterotaxy, including situs inversus totalis (Perles et al., 2012).

Autosomal visceral heterotaxy-8 (HTX8) is an autosomal recessive developmental disorder characterized by visceral situs inversus associated with complex congenital heart malformations caused by defects in the normal left-right asymmetric positioning of internal organs (summary by Vetrini et al., 2016). For a discussion of the genetic heterogeneity of visceral heterotaxy, see HTX1 (306955).

Primary ciliary dyskinesia-40 (CILD40) is an autosomal recessive disorder with a relatively mild respiratory phenotype compared to other CILDs. Patients present in childhood with mild upper respiratory symptoms and infections, but typically do not develop serious lung disease. Nitric oxide levels are low-normal or normal. All reported patients have had situs inversus, including several with severe congenital cardiac malformations, but left-right body asymmetry is still theoretically random and would occur in 50% of patients (summary by Loges et al., 2018). For a discussion of genetic heterogeneity of primary ciliary dyskinesia and Kartagener syndrome, see CILD1 (244400).

Biliary, renal, neurologic, and skeletal syndrome (BRENS) is an autosomal recessive complex ciliopathy with multisystemic manifestations. The most common presentation is severe neonatal cholestasis that progresses to liver fibrosis and cirrhosis. Most patients have additional clinical features suggestive of a ciliopathy, including postaxial polydactyly, hydrocephalus, retinal abnormalities, and situs inversus. Additional features of the syndrome may include congenital cardiac defects, echogenic kidneys with renal failure, ocular abnormalities, joint hyperextensibility, and dysmorphic facial features. Some patients have global developmental delay. Brain imaging typically shows dilated ventricles, hypomyelination, and white matter abnormalities, although some patients have been described with abnormal pituitary development (summary by Shaheen et al., 2020 and David et al., 2020).

Multiple types of congenital heart defects-8 (CHTD8) is characterized by cardiac septal defects, double-outlet right ventricle, unbalanced complete atrioventricular canal, and valvular anomalies, as well as vascular anomalies including dextroposition of the great arteries, anomalous pulmonary venous return, and superior vena cava to left atrium defect. Patients may also exhibit laterality defects, including dextrocardia, atrial isomerism, dextrogastria, left-sided gallbladder, and intestinal malrotation (Zaidi et al., 2013; Granadillo et al., 2018).

Multiple types of congenital heart defects-9 (CHTD9) is characterized by common arterial trunk (truncus arteriosus communis) in most patients, associated with other cardiac defects, including tetralogy of Fallot, interrupted aortic arch, right aortic arch, ventricular hypoplasia, and hypoplastic left heart, as well as other vascular and valvular anomalies (Ta-Shma et al., 2013; Guimier et al., 2023). For a general phenotypic description and discussion of genetic heterogeneity of multiple types of congenital heart defects, see CHTD1 (see 306955).