Down syndrome

Description

A chromosomal dysgenesis syndrome resulting from a triplication or translocation of chromosome 21. Down syndrome occurs in approximately 1:700 live births. Abnormalities are variable from individual to individual and may include intellectual disability, retarded growth, flat hypoplastic face with short nose, prominent epicanthic skin folds, small low-set ears with prominent antihelix, fissured and thickened tongue, laxness of joint ligaments, pelvic dysplasia, broad hands and feet, stubby fingers, transverse palmar crease, lenticular opacities and heart disease. Patients with Down syndrome have an estimated 10 to 30-fold increased risk for leukemia; most have symptoms of Alzheimer's disease by age 40. Also known as trisomy 21 syndrome. --2004; A chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21. Clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, Brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, Simian crease, and moderate to severe intellectual disability. Cardiac and gastrointestinal malformations, a marked increase in the incidence of LEUKEMIA, and the early onset of ALZHEIMER DISEASE are also associated with this condition. Pathologic features include the development of NEUROFIBRILLARY TANGLES in neurons and the deposition of AMYLOID BETA-PROTEIN, similar to the pathology of ALZHEIMER DISEASE. (Menkes, Textbook of Child Neurology, 5th ed, p213); A disorder caused by the presence of all or part of an extra 21st chromosome, characterized by structural abnormalities throughout the body. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. (Adapted from Wikipedia); Down syndrome is a chromosomal abnormality caused by the presence of a third (partial or total) copy of the chromosome 21 genetic material and that is characterized by variable intellectual disability, muscular hypotonia, and joint laxity, often associated with a characteristic facial dysmorphism and various anomalies such as cardiac, gastrointestinal, or endocrine defects.; May be replaced by Down syndrome (http://www.orpha.net/ORDO/Orphanet_870) in the future