Write a brief note on Down syndrome.
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[Textbook question 4a pg no.193]
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Solution
Answer:
Down syndrome is the disorder arising due to chromosomal abnormality.
This is the first discovered and described the chromosomal disorder in human beings.
This disorder is characterized by the presence of 47 chromosomes. It is described as the trisomy of the 21st pair.
Infants with this disorder have one extra chromosome with the 21st pair in every cell of the body. Therefore, they have 47 chromosomes instead of 46.
Children suffering from Down syndrome are usually mentally retarded and have a short lifespan. Mental retardation is the most prominent characteristic.
Other symptoms include short height, short wide neck, flat nose, short fingers, scanty hair, single horizontal crease on palm and a life expectancy of about 16-20 years.