Cardiac and laterality defects
Overview
A rare congenital disorder involving congenital heart abnormalities as well as laterality defects which are disruptions to the body's normal left-right plan. For example, internal organs may be located on the wrong side of the body.
Symptoms
* Situs inversus * Heart defects * Asplenia * Midline liver * Heart located on right side of chest
Causes
the genetic causes of CHD are being elucidated, substantial genetic heterogeneity (ie, mutations in different genes giving rise to the same phenotype) is becoming apparent. Another confounding factor in the genetic analysis of CHD has been the reduced penetrance of the mutant phenotypes, in which some individuals carrying the disease-causing mutations appear to be free of CHD. A third confounding factor has been variable expressivity.
Diagnosis
Laterality defects may be discovered before birth and in infancy because of associated heart defects or other health problems. Laterality defects also may remain asymptomatic in childhood and are discovered by chance in adult life as affected individuals seek medical attention for an unrelated condition. Clinical testing for several genes associated with laterality defects (ACVR2B, CFC1, CRELD1, EBAF, NKX2-5, and ZIC3) is available; however, diagnosis is still primarily based on imaging through means such as ultrasound, magnetic resonance imaging (MRI), and computed tomography (CT) scan.
Prognosis
Many patients with laterality sequence defects such as total situs inversus present with no significant medical problems and have normal life expectancy. Total organ reversal results in normal relationships between the left-right positions of the organs and their blood supplies. In other forms of laterality sequence defects, such as those associated with Kartagener's syndrome, issues such as chronic respiratory problems and infertility can occur.
Treatment
The treatment and management of laterality sequence defects depend on the type of defect. Infants and children with laterality defects can have congenital heart defect and other associated birth defects that require surgery. Many adults with incidental detection of their laterality sequence anomalies will not need special treatment or management unless they are ill or need surgery. The recognition of situs inversus is important for preventing surgical mishaps that result from the failure to recognize reversed anatomy or an atypical history.