In most cases of Down syndrome, the person inherits two chromosomes 21 from the mother (instead of one) and one chromosome 21 from the father, resulting in three copies of chromosome 21 instead of two (hence Down syndrome is also known as trisomy 21). One set of 23 chromosomes comes from the mother (egg cell or ovum) and the other half of the 23 pairs come from the father (sperm cell). Human cells normally contain 46 chromosomes that can be arranged in 23 pairs. Chromosomes contain the genes that carry all the information necessary to properly develop and maintain our bodies. The cause of Down syndrome was discovered rather recently in 1959.ĭown syndrome is a genetic disorder caused by the presence of an extra chromosome 21. In 1866, Doctor John Langdon Down first described Down syndrome as a disorder, but he misunderstood how Down syndrome arises. The earliest known depiction of a person with Down syndrome is an angel in a Flemish painting dated 1515. The average life span is greater than 55 years. A majority of infants with Down syndrome survive 1 year, and half of the people with Down syndrome live longer than 50 years. the hands tend to be wide with short fingers with a single flexion crease in the palm.ĭue to recent advances in medical care and social inclusion, life expectancy has increased dramatically for individuals with Down syndrome.The hallmark symptoms and signs of Down syndrome are The degree to which an individual is affected by these characteristics varies from mild to severe. 4 Hallmark symptoms of Down syndrome are a flat face, a small head, a short neck, and a wide hand with short fingers.ĭown syndrome is also often associated with heart defects, leukemia, and early-onset Alzheimer's disease. Down syndrome is caused by the presence of an extra chromosome.
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