Michael Reagan, Biology
Hypoplastic left heart syndrome (HLHS) collectively refers to a range of congenital heart defects, all involving some degree of left ventricular hypoplasia, or underdevelopment of the left ventricle. Additionally, HLHS often involves coarctation of the aorta, and can also include hypoplasia of the ascending aorta, as well as mitral and/or aortic valve stenosis or atresia. HLHS is extremely rare, as it has been reported to occur in only 1 in 5000 live births each year. The cause of HLHS is currently unknown, however much research is being done to discover how and why these defects occur.
HLHS is known to be familially inherited in some instances and is also associated with many well-characterized genetic disorders, including Holt-Oram syndrome, Turner’s syndrome, Noonan syndrome, Smith-Lemli-Opitz syndrome, as well as trisomies 13, 18, and 21. Additionally, an autosomal recessive pattern of inheritance has been found amongst some siblings, however, no specific genes have been implicated. Incidence of HLHS also varies significantly in certain geographical regions and some studies have found a seasonal correlation in HLHS, indicating a possible environmental cause.
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