A healthy couple with a history of three previous spontaneous abortions has just had a child with cri-du-chat syndrome, a disorder caused by a terminal deletion of chromosome 5. Their physician orders karyotype analysis of both parents and of the child. The karyotype results for chromosomes 5 and 12 are shown here. Which parent has an abnormal karyotype? How can you tell? What is the nature of the abnormality?
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
6. Chromosomal Variation
Chromosomal Rearrangements: Deletions
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following genetic diseases is an example of a chromosomal deletion?
A
Down syndrome
B
Familial down syndrome
C
Cri du Chat syndrome
D
Klinefelter's Disease

1
Understand the concept of chromosomal deletion: A chromosomal deletion occurs when a part of a chromosome is missing or deleted, leading to a loss of genetic material.
Review the characteristics of Cri du Chat syndrome: This genetic disorder is caused by a deletion of a portion of chromosome 5, specifically the short arm (5p).
Compare Cri du Chat syndrome with other listed conditions: Down syndrome is caused by an extra chromosome 21 (trisomy 21), not a deletion. Familial Down syndrome involves a translocation, and Klinefelter's Disease is due to an extra X chromosome (XXY).
Identify the key difference: Cri du Chat syndrome is the only condition among the options that involves a chromosomal deletion.
Conclude that understanding the type of chromosomal abnormality is crucial in identifying genetic diseases associated with deletions.
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Chromosomal Rearrangements: Deletions practice set
