The following diseases constitute the Chromosome Instability Syndromes - Ataxia telangiectasia - Fanconi anemia - Bloom syndrome - Xeroderma Pigmentosum: The following statements on the syndromes are correct EXCEPT:

Correct Answer: A

Rationale: A is incorrect; radiation is avoided due to DNA repair defects increasing sensitivity.

Correct Answer: C

Rationale: Telomeres don’t code for genes (C is false). Rationale: Telomeres are TTAGGG repeats (A), shorten with replication (B), and protect chromosome ends (D). They’re non-coding, and telomerase activity is high in cancer (E), making 'C' the exception.

Correct Answer: C

Rationale: Down syndrome is 47, XX, +21, not +18 (C is mismatched). Rationale: Patau is +13 (A), Edwards is +18 (B), but Down is +21, making 'C' incorrect.

Correct Answer: B

Rationale: Triploidy is incompatible with adult life (B). Rationale: 69, XXY (not listed) or similar triploids (3n) occur but are lethal or result in miscarriage. 92 (4n) or 23 (n) don’t fit triploidy (3n=69). Adults don’t survive triploidy.

Correct Answer: D

Rationale: Deletion of a light band (D) has more impact. Rationale: Light bands (euchromatin) are gene-rich; deletions (loss of function) often cause disease (e.g., 5p-). Duplications (A, B repeated) may be milder; single-band changes can matter (C false).