1. Tardigrade
  2. Question
  3. Biology
  4. Three copies chromosome - 21 in a child with Down's syndrome have been analysed using molecular biology technology to detect any possible DNA polymorphism with reference to different alleles located on chromosome - 21 Results showed that out of 3 copies 2 of the chromosomes of the child contain the same alleles as one of the mother's alleles. Based on this when did the non-disjunction event most likely occur?

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Q. Three copies chromosome - $21$ in a child with Down's syndrome have been analysed using molecular biology technology to detect any possible $DNA$ polymorphism with reference to different alleles located on chromosome - $21 $ Results showed that out of $3$ copies $2$ of the chromosomes of the child contain the same alleles as one of the mother's alleles. Based on this when did the non-disjunction event most likely occur?

Principles of Inheritance and Variation

Solution:

Correct answer is (b) Maternal meiosis-I