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प्रश्न
What is Down’s syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years?
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उत्तर
Down’s syndrome is a human genetic disorder caused due to trisomy of chromosome no. 21. Such individuals are aneuploid and have 47 chromosomes. (2n + 1) The symptoms include mental retardation, growth abnormalities, constantly open mouth, dwarfness etc. The reason for the disorder is the non-disjunction (failure to separate) of homologous chromosome of pair 21 during meiotic division in the ovum. The chances of having a child with Down’s syndrome increase with the age of the mother (+ 40) because ova are present in females. since their birth and therefore older cells are more prone to chromosomal non-disjunction because of various physico-chemical exposures during the mother’s life-time.
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संबंधित प्रश्न
Females with Turners’ syndrome have
Pataus’ syndrome is also referred to as ____________.
Which of the following is not correct?
Define aneuploidy. How is it different from polyploidy? Describe the individuals having following chromosomal abnormalities.
- Trisomy of 21st Chromosome
- XXY
- XO
Match List I with List II.
| List I | List II | ||
| A. | Down’s syndrome | I. | 11th chromosome |
| B. | α-Thalassemia | II. | ‘X’ chromosome |
| C. | β-Thalassemia | III. | 21st chromosome |
| D. | Klinefelter’s syndrome | IV. | 16th chromosome |
Choose the correct answer from the options given below:
Which of the following karyotypes represents Down's Syndrome?
What is the primary cause of Down's Syndrome in approximately 95% of cases?
Which clinical feature is present in approximately 50% of Down's Syndrome cases?
Which of the following is a characteristic feature of Turner's Syndrome?
Which of the following sex chromosome aneuploidies results in phenotypically normal females who are taller than average?
What is Cri-du-chat syndrome associated with?
What type of structural abnormality is represented by a chromosomal segment that detaches and reattaches in reverse orientation?
Which structural chromosomal abnormality is exemplified by the Philadelphia chromosome associated with Chronic Myeloid Leukaemia?
What is the incidence of Edwards Syndrome in relation to other trisomies?
Which type of numerical abnormality is represented by a formula of 2n + 2?
What does the term 'hypogonadism' refer to in Klinefelter's Syndrome?
Which trisomy is associated with kidney and lung defects in addition to cardiac abnormalities?
