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Down Syndrome Counselling
Down Syndrome
Condition
Down syndrome is a genetic condition, it is a mental disability and causes developmental delays. Some common physical conditions of Down syndrome are compressed facial features and a small head and neck, unusually shaped eyes and ears, hands with a single crease in the palm, short fingers and small hands and feet, extreme flexibility, short height, slow physical development and finally small white spots on the iris called Brushfield spots. Children with Down syndrome are also usually socially and mentally developmentally delayed. There is a large span of developmental problems, but some more common ones are: impulsive behaviour, poor judgement, short attention span and slow learning. Children with Down syndrome are also more at risk of other health problems caused by their unique physical condition.
Types
There are three types of Down syndrome: Trisomy 21, mosaic Down syndrome and translocation Down syndrome. Trisomy 21 is the most common type of Down syndrome, and is caused when an extra chromosome 21 is made in cell division during meiosis (the development of the sperm or egg cell). Mosaic Down syndrome is very rare, it is a condition where only some cells have an extra copy of chromosome 21. This type of Down syndrome develops during fertilization. Translocation Down syndrome occurs when part of chromosome 21 attaches or translocates to another chromosome, the child therefore has a two copies of chromosome 21 and extra material of chromosome 21 attached to another chromosome.
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Probability
Each year in the US , approximately 6,000 babies are born with Down syndrome, which is about 1 in every 700 babies born. The probability of a mother having a child with Down syndrome increases as her age increases.
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At age 25, the risk of having a baby with Down syndrome is 1 in 1,250.
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At age 30, the risk is 1 in 1,000.
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At age 35, the risk is 1 in 400.
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At age 40, the risk is 1 in 100.
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At age 45, the risk is 1 in 30.
Egg or Sperm
Every human being has 46 chromosomes arranged in 23 pairs. Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46. Durng meiosis, a failure of the 21st chromosome to separate results in the sperm or egg cell being produced with an extra copy of chromosome 21. In 90% of Trisomy 21 cases, the additional chromosome comes from the mother's egg rather than the father's sperm.