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Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. [3] It is usually associated with developmental delays, mild to moderate intellectual disability, and characteristic physical features. [1] [12] There are three types of Down syndrome, the ...
Genetics of Down syndrome. Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole ( trisomy 21) or part (such as due to translocations ). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy ...
Autism spectrum disorder (ASD) is referred to as syndromic when it is one of the many characteristics associated with a broader medical condition, generally a syndrome . Syndromic autism represents about 25% of the total ASD cases. [4] [5] In most [quantify] cases, its etiology is known. [2] [4]
Down syndrome is a genetic disorder that often results in distinct physical differences and intellectual disability. According to the Centers for Disease Control, each year about 6,000 babies are ...
John Langdon Down. John Langdon Haydon Down (18 November 1828 – 7 October 1896) was a British physician best known for his description of the genetic condition now known as Down syndrome, which he originally classified in 1862. He is also noted for his work in social medicine and as a pioneer in the care of mentally disabled patients.
Tetralogy of Fallot ( TOF ), formerly known as Steno-Fallot tetralogy, [9] is a congenital heart defect characterized by four specific cardiac defects. [4] Classically, the four defects are: [4] pulmonary stenosis, which is narrowing of the exit from the right ventricle; a ventricular septal defect, which is a hole allowing blood to flow ...
Down syndrome research. Research of Down syndrome-related genes is based on studying the genes located on chromosome 21. In general, this leads to an overexpression of the genes. [1] [2] Understanding the genes involved may help to target medical treatment to individuals with Down syndrome. It is estimated that chromosome 21 contains 200 to 250 ...
Research has found that there is a correlation between advanced paternal age and risk of birth defects such as limb anomalies, syndromes involving multiple systems, and Down syndrome. Recent studies have concluded that 5-9% of Down syndrome cases are due to paternal effects, but these findings are controversial.