Molecular and cellular mechanism Several genes have been identified in normal development of the right-left axis. These genes have been extensively researched. Gene mutations that lead to atrial isomerism is a growing area of research. Mutations in genes that encode proteins in the TGF-beta pathway, including NODAL, NKX2-5, and ZIC3, have been linked to tetralogy of fallot and hypoplastic left heart syndrome. Mutations in the ZIC3 gene, which encodes for the first zinc finger transcription factor, is linked to a 50% risk of atrial isomerism in families. It is also an X-linked disorder, so testing for ZIC3 mutations is highly encouraged in male births. The most prevalent and best characterized genetic associations of heterotaxy include: Type OMIM Gene Locus HTX1 ZIC3 Xq26.2 HTX2 CFC1 2q21.1 HTX3 PA26 6q21 HTX4 ACVR2B 992 HTX5 NODAL 10q22.1 HTX6 614779 CCDC11 18q21.1 Classical pathology * Cardiac looping malformations: * Fallot's tetralogy * transposition of the great vessels * Ventricular and atrial septal defects. * Deranged abdominal organ asymmetry: * The stomach and spleen are prone to isolated reversal * The stomach, liver, and a single adrenal gland are occasionally found in the midline. * Organ malformations: * asplenia and polysplenia often lead to sepsis * More rarely, the head of the pancreas fails to form * Horseshoe kidneys develop, which can lead to cancer, kidney stones, and/or infection. * Malrotation errors cause volvulus and/or faulty peritoneal attachments, which completely obstruct the bowel. * Vascular abnormalities: * Interrupted inferior vena cava, * Bilateral superior or inferior venae cavae * Intrahepatic interruption of the inferior vena cava with connection to the azygos or hemiazygos veins * Aberrant portal veins. Bronchial tree and lungs Pathophysiology in the bronchial tree can be observed by radiography. Under normal development, the bronchial tree consists of two main bronchi that are anatomically different: * Hyparterial bronchus (below the pulmonary artery): supplies blood to the bi-lobed left lung * Eparterial bronchus (adjacent to the artery): supplies blood to the tri-lobed right lung In<unk> , there is a duplication of either the hyparterial or eparterial bronchus. These features are not associated with any significant clinical complications. Mechanisms leading to bronchial duplication are not thoroughly understood. In pulmonary valve stenosis, there is a reduction in blood flow to the lungs due to an obstruction of the heart at the pulmonic valve. This contributes to cyanosis and pulmonary hypertension.
Situs ambiguus
Situs inversus
Pulmonary agenesis
Double aortic arch
Pulmonary atresia
Gastroschisis
Diaschisis
Cranioschisis