Echocardiographic screening in patients with genetic disease plays an important role in daily practice. Early detection of possible cardiac complications is essential and enables prompt treatment. Some disorders have very typical echocardiographic features. This chapter describes some of the most common genetic disorders associated with heart disease.
Williams syndrome
Williams syndrome is caused by a heterozygous deletion of a specific region of chromosome seven that contains, among others, the elastin gene. Affected patients have distinctive facial features, learning difficulties, and loose skin due to the reduced deposition of elastin. Cardiac abnormalities are present in the vast majority of cases and typically include supravalvar aortic stenosis, diffuse aortic hypoplasia, and stenotic lesions affecting the proximal and distal pulmonary arterial tree. Some patients also experience coronary artery involvement.
Noonan syndrome
Noonan syndrome has been associated with mutations in a number of genes. From a clinical point of view, the syndrome is characterized by facial dysmorphism, short stature, and chest deformities, but the phenotypic expression varies widely among patients. If present, cardiac defects typically include valvar pulmonary stenosis, hypertrophic cardiomyopathy, and atrial septal defects.
Marfan syndrome
Marfan syndrome is a multisystemic connective tissue disorder affecting the heart, blood vessels, eyes, spine, and chest. It is caused by mutations in the FBN1 gene, coding for the fibrillin-1 protein. From a cardiac point of view, the hallmark of the disease is aortic root dilatation, which may be complicated by aortic dissection. Pulmonary artery dilatation is rare as the pressure is much lower in the pulmonary artery compared to the aorta. Mitral valve prolapse represents another common feature associated with the syndrome. Tricuspid valve involvement may also occur in severe neonatal forms of the disease.
Turner syndrome
Turner syndrome is caused by a partial or complete loss of one of the two X chromosomes and therefore only affects women. From a clinical point of view, the syndrome is characterized by a broad chest, wide neck, low-set ears, low hairline, edema in hands and feet (particularly in neonates), and slow growth. Approximately one-third of the patients with Turner syndrome have a bicommissural (bicuspid) aortic valve or develop coarctation of the aorta.
Down syndrome
Congenital heart defects occur in approximately half of the children with trisomy 21 and are a major cause of early-life mortality and morbidity. Defects of the atrio-ventricular septum, encountered in approximately one-third of the patients, represent by far the most common cardiac diagnosis. Atrial or ventricular septal defects, patent ductus arteriosus, and tetralogy of Fallot account for the majority of the remaining defects.
DiGeorge syndrome
DiGeorge syndrome, also known as 22q11 deletion syndrome, is characterized by distinctive facial features and thymic and parathyroid hypoplasia, resulting in immunodeficiency and hypocalcemia. Cardiac defects are not uncommon and typically affect the ventricular outflow tracts. The most common cardiac diagnoses include interrupted aortic arch and truncus arteriosus. Tetralogy of Fallot, double-outlet right ventricle, or large ventricular septal defects may also occur.
Glycogen storage diseases
Glycogen storage diseases are metabolic disorders characterized by abnormal glycogen synthesis or breakdown. This results in an accumulation of glycogen in the skeletal muscles, causing generalized hypotonia. Myocardial involvement may also occur, leading to the development of cardiomyopathy. Enzyme replacement therapy is the only treatment available in some cases.
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