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Principles of Inheritance and Variation
Chromosomal Disorders – Down's Syndrome
3 questions from 3 papers, each with its answer.
- questions
- 3
- papers
- 3
- years asked, 2017–2026
- 2 of 10
- of Principles of Inheritance and Variation
- 1.52%
Appears in
Concepts tested
- Chromosomal disorders - Down's syndrome
- features of Down's syndrome
- Transmission of trisomy 21
All Questions
2023 1 question
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Broad palm with single palm crease is visible in a person suffering from
Down's syndrome shows a broad palm with a characteristic palm crease.
Down's Syndrome: The cause of this genetic disorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21). This disorder was first described by Langdon Down (1866). The affected individual is short statured with small round head, furrowed tongue and partially open mouth. Palm is broad with characteristic palm crease. Physical, psychomotor and mental development is retarded.
2022 Phase 2 1 question
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If a female individual is with small round head, furrowed tongue, partially open mouth and broad palm with characteristic palm crease. Also the physical, psychomotor and mental development is retarded. The karyotype analysis of such an individual will showThese are features of Down's syndrome, caused by the presence of an additional copy of chromosome 21 (trisomy 21, 2n + 1). This aneuploidy results from non-disjunction during gamete formation.
2003 AIPMT 1 question
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Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder :-An affected mother has three copies of chromosome 21 (trisomy 21).
During meiosis, the three chromosomes 21 are distributed so that half of her eggs receive two copies of chromosome 21 and half receive one copy.
The normal father gives one chromosome 21 in every sperm.
Egg with two copies + sperm with one = trisomy 21 (Down's syndrome); egg with one copy + sperm with one = normal.
So about 50% of the offspring would be affected.