In early cell-division stages, cells can have too few or too many chromosomes {chromosome abnormality}, such as in Down's syndrome. One birth in 250 has chromosome abnormality. New strain 0139 flourished in 1993.
Human #21 chromosome can have three copies {mongolism} {Down's syndrome} {Down syndrome}, rather than two, resulting in mental retardation. Symptoms are flattened face, thick and large tongue, extra eyelid folds, uncoordinated movements, and IQ between 20 and 60. Down's syndrome patients over 35 years have same pathological brain changes as Alzheimer's patients. Extra 21st chromosomes relate to infectious hepatitis.
Extra chromosome 13 causes mental retardation {Patau syndrome}.
4-Medicine-Disease-Kinds-Genetic Disease-Chromosome
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Date Modified: 2022.0225