Q.Identify chromosomal disorder caused due to non-disjunction of 21st number of chromosome and enlist its symptoms.
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Start your 14-day free trial to unlock the full solution →Down's syndrome (trisomy 21).
Non-disjunction of chromosome 21 during gamete formation produces trisomy 21, the chromosomal disorder called Down's syndrome.
Down's syndrome arises when chromosome 21 fails to separate properly (non-disjunction) during meiosis in one of the parents' germ cells, so the resulting gamete carries two copies of chromosome 21 instead of one; after fertilisation with a normal gamete, the zygote ends up with three copies of chromosome 21 (trisomy 21) instead of the usual two, giving 47 chromosomes in total instead of 46. Individuals with Down's syndrome typically show characteristic symptoms: varying degrees of mental retardation/intellectual disability, short stature, a flattened facial profile and small skull, oblique/upward-slanting eyes with an epicanthic fold, a short broad neck, a large protrudi …
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