Question

Down syndrome is caused by an extra copy of chromosome number 21. What percentage of offsprings produced by an affected mother and a normal father would be affected by this disorder?

(a) 50% (b) 25% (c) 100% (d) 75%​

Answer 1

Answer:-

50%

According to the question the effected of normal Father and normal mother produced the percentage off springs The percentage of off springs produced is 50%

Answer 2

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Down's syndrome is the result of trisomy in which chromosome number 21st contains an extra copy of chromosome (2A + 1). Affected mother will produce 50% normal egg cells and rest 50% eggs are of abnormal type. 

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(n + 1) ? abnormal egg n ? normal egg   Fusion of normal egg with a normal sperm (comes from father) produces a normal offspring while fusion of abnormal egg with a normal sperm will produce an abnormal offspring.

Extra Information :-

Question:-What causes Down syndrome in a child?

When a baby is conceived, a normal egg cell and normal sperm cell start with 46 chromosomes. The egg and sperm cells then divide in half. The egg and sperm cells then have 23 chromosomes each. When a sperm with 23 chromosomes fertilizes an egg with 23 chromosomes, the baby will then have a complete set of 46 chromosomes. Half are from the father and half are from the mother.

Question :-Which children are at risk for Down syndrome?

A mother’s age at her child’s birth is the only factor linked to the risk of having a baby with Down syndrome. This risk increases with each year of age, especially after age 35. But younger women are more likely to have babies than older women. So most babies with Down syndrome are born to women younger than 35.

Question :- What are the symptoms of Down syndrome in a child?

✔Symptoms can occur a bit differently in each child. They can include:

✔Eyes that slant upward

✔Small ears that may fold over slightly at the top

✔Small mouth that makes the tongue appear large

✔Small nose with a flattened bridge

✔Short neck

✔Small hands with short fingers

✔2 instead of 3 palm creases, including one across the palm and one around the base of the thumb

✔Short height

✔Loose joints

✔Heart defects

✔Intestinal problems

✔Vision problems

✔Hearing problems

✔Thyroid problems

✔Blood conditions, such as leukemia, and risk for infections

✔Learning problems

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Down syndrome can often be diagnosed before birth. After birth, your baby may be diagnosed with a physical exam. The healthcare provider may also take a blood sample.

There is no cure for Down syndrome, but treatment is available to help your child.

child may need physical, occupational, and speech therapy to help with his or her development. Many children are helped with early intervention and special education.

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