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. Do the karyotypes of the parents help explain the occurrence of the three previous spontaneous abortions? Explain.

Verified step by step guidance

1. Identify the genetic abnormality associated with cri-du-chat syndrome, which is a terminal deletion on chromosome 5.
2. Review the karyotype results of the child to confirm the presence of the deletion on chromosome 5.
3. Examine the karyotype results of both parents to determine if either parent carries a balanced translocation or any other chromosomal abnormality that could lead to unbalanced gametes.
4. Consider if a balanced translocation in one of the parents could result in gametes with unbalanced chromosomal content, potentially leading to spontaneous abortions.
5. Conclude whether the presence of a balanced translocation or other chromosomal abnormality in the parents could explain the history of spontaneous abortions.

Key Concepts

Karyotype Analysis

Karyotype analysis is a laboratory technique that examines the number and structure of chromosomes in an individual's cells. It can identify chromosomal abnormalities, such as deletions, duplications, or translocations, which may lead to genetic disorders or reproductive issues. In this case, analyzing the karyotypes of the parents and child can reveal whether chromosomal abnormalities contributed to the spontaneous abortions.

Cri-du-chat Syndrome

Cri-du-chat syndrome is a genetic disorder caused by a deletion of a portion of chromosome 5, leading to developmental delays, distinctive facial features, and a characteristic high-pitched cry. Understanding this syndrome is crucial as it may indicate underlying genetic issues in the parents that could also relate to their history of spontaneous abortions, potentially due to chromosomal abnormalities.

Spontaneous Abortion and Genetic Factors

Spontaneous abortion, or miscarriage, often occurs due to genetic abnormalities in the embryo, which can arise from chromosomal issues in the parents. Factors such as balanced translocations or other chromosomal rearrangements can lead to embryos with unviable genetic combinations, resulting in pregnancy loss. Analyzing the parents' karyotypes may reveal such genetic factors that could explain their history of miscarriages.