Cytogenetic diagnosis — which conditions can be detected by karyotyping as an unbalanced chromosomal complement?
-
ADown’s syndrome (trisomy 21)
-
BTurner’s syndrome (45,X)
-
CKlinefelter’s syndrome (47,XXY)
-
DAll of these
-
EOnly microdeletions below 100 kb
Answer
Correct Answer: All of these
Explanation
Introduction / Context:Karyotyping visualizes whole chromosomes to detect numerical abnormalities and large structural rearrangements. It remains a cornerstone for diagnosing aneuploidies and sex chromosome disorders.
Given Data / Assumptions:
- We are asked about conditions resulting from unbalanced complements.
- Examples include autosomal trisomy and sex chromosome aneuploidies.
- Karyotyping’s resolution is on the order of several megabases, not tiny microdeletions.
Concept / Approach:
Down’s (47, +21), Turner’s (45, X), and Klinefelter’s (47, XXY) are classic diagnoses by karyotype, clearly showing gains or losses of whole chromosomes or sex chromosomal complements.
Step-by-Step Solution:
List candidate disorders and their cytogenetic signatures.Confirm that each is a whole-chromosome aneuploidy.Recognize detectability via standard metaphase karyotyping.Select “All of these.”Verification / Alternative check:
Clinical cytogenetics routinely confirms these diagnoses with karyogram analysis; additional techniques (FISH, microarrays) complement but are not required for whole-chromosome changes.
Why Other Options Are Wrong:
“Only microdeletions below 100 kb” are generally below karyotype resolution and require higher-resolution methods.
Common Pitfalls:
Confusing karyotyping’s strengths (aneuploidy) with its limitations (small CNVs).
Final Answer:
All of these