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. What is the approximate probability that the next child of this couple will have cri-du-chat syndrome?

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 locus. This condition is characterized by distinctive features such as a high-pitched cry resembling a cat, developmental delays, and various physical abnormalities. Understanding the genetic basis of this syndrome is crucial for assessing the risk of recurrence in future pregnancies.

Karyotype Analysis

Karyotype analysis is a laboratory technique used to visualize an individual's chromosomes, allowing for the identification of chromosomal abnormalities such as deletions, duplications, or translocations. In this case, analyzing the karyotypes of the parents and the child can help determine if either parent carries a chromosomal abnormality that could increase the risk of having another child with cri-du-chat syndrome.

Recurrence Risk

Recurrence risk refers to the probability that a genetic disorder will occur again in future offspring after one affected child has been born. This risk can be influenced by factors such as parental genetic contributions, family history, and specific chromosomal findings. In the context of this couple, understanding their karyotype results will be essential in calculating the likelihood of having another child with cri-du-chat syndrome.