A couple planning their family are aware that through the past three generations on the husband's side a substantial number of stillbirths have occurred and several malformed babies were born who died early in childhood. The wife has studied genetics and urges her husband to visit a genetic counseling clinic, where a complete karyotype-banding analysis is performed. Although the tests show that he has a normal complement of 46 chromosomes, banding analysis reveals that one member of the chromosome 1 pair (in group A) contains an inversion covering 70 percent of its length. The homolog of chromosome 1 and all other chromosomes show the normal banding sequence. How would you explain the high incidence of past stillbirths?

Key Concepts

Chromosomal Inversion

A chromosomal inversion occurs when a segment of a chromosome is reversed end to end. This can disrupt gene function and lead to abnormal gene expression. In the case of the husband, the inversion on chromosome 1 may affect genes crucial for development, potentially contributing to the observed stillbirths and malformations in offspring.

Karyotype Analysis

Karyotype analysis is a laboratory technique that examines the number and structure of chromosomes in an individual's cells. It helps identify chromosomal abnormalities, such as inversions, deletions, or duplications. In this scenario, the normal karyotype indicates no major chromosomal abnormalities, but the inversion may still have significant implications for fertility and fetal development.

Genetic Counseling

Genetic counseling is a process that provides individuals or couples with information about genetic conditions and the risks of inherited disorders. It is particularly important for families with a history of genetic issues, as it helps them understand potential risks and make informed decisions about family planning. The wife's suggestion for counseling reflects a proactive approach to addressing their family's genetic history.