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. Are the chromosomes in the child consistent with those expected in a case of cri-du-chat syndrome? Explain your reasoning.

Key Concepts

Cri-du-chat Syndrome

Cri-du-chat syndrome is a genetic disorder caused by a deletion of a portion of chromosome 5, specifically at the 5p15.2 region. This condition is characterized by distinctive features such as a high-pitched cry resembling that of a cat, developmental delays, and various physical anomalies. Understanding the genetic basis of this syndrome is crucial for analyzing the karyotype results and determining if the child's chromosomes align with the expected genetic profile.

Karyotype Analysis

Karyotype analysis is a laboratory technique used to visualize an individual's chromosomes, allowing for the assessment of chromosomal number and structure. This analysis can identify chromosomal abnormalities, such as deletions, duplications, or translocations, which are critical in diagnosing genetic disorders. In the context of cri-du-chat syndrome, examining the karyotype of the child will help confirm the presence of the specific deletion on chromosome 5.

Chromosomal Deletion

A chromosomal deletion refers to the loss of a segment of DNA from a chromosome, which can lead to genetic disorders if critical genes are missing. In cri-du-chat syndrome, the deletion occurs at the terminal end of chromosome 5, resulting in the loss of important genetic material. Understanding the implications of such deletions is essential for interpreting karyotype results and assessing the genetic health of the child.