International Technologist in Cytogenetics ASCP Practice Test

When considering karyotypic abnormalities that may necessitate parental chromosomal analysis, it's important to focus on structural abnormalities, particularly those that involve translocations or other alterations that could have been inherited.

The presence of the marker 46,XX,der(14;21)(q10;q10),+21 indicates a balanced translocation involving chromosomes 14 and 21 and an additional chromosome 21. This type of abnormality can be significant because it may lead to reproductive issues, such as risks of chromosomal imbalances in offspring. When one parent carries a balanced translocation, there is a possibility of having a child with an unbalanced chromosomal complement, depending on how the chromosomes segregate during gamete formation. Therefore, knowing the parental karyotypes can provide critical information about the risk of recurrence in future pregnancies.

In contrast, the other karyotypes listed do not indicate the necessity for parental analysis in a similar way. For instance, 46,XY,+18 and 50,XX,+21 represent aneuploidies of chromosomes 18 and 21, respectively. These conditions typically arise as random events during gametogenesis and are less likely to be inherited, thus parental analysis may not add significant value in understanding the