Amniocentesis Results: What Does 47 XY + mar Mean?

Amniocentesis Report

Hello Doctor, I am currently 20 weeks pregnant.
At 16 weeks, I underwent amniocentesis and received the results from the chromosomal microarray two weeks later, which confirmed no issues.
However, three weeks later, the amniocentesis report indicated that out of 140 cells tested, 6 small cells were scattered, and it is uncertain which chromosome pair they belong to.
The amniocentesis report shows 47, XY + mar [6] / 46, XY [134].
The current approach is to conduct chromosomal analysis on both parents' blood to check for any hereditary conditions.
If it is not hereditary, it may be a spontaneous mutation.
What potential impacts could this have?

Huang, 30~39 year old female. Ask Date: 2016/04/15

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, it is possible that you and your spouse may have passed on genetic traits to your child.
It is advisable to consult with Dr.
Ke Tsang-Ming at Chuanwei Hospital.
Wishing you good health.

Reply Date: 2016/04/15

More Info

The results of your amniocentesis indicate a chromosomal abnormality, specifically "47 XY + mar [6]/46 XY [134]." This means that among the 140 cells analyzed, 6 cells showed an extra chromosome (47 total), while the remaining 134 cells were normal (46 chromosomes). The notation "+ mar" refers to the presence of a "marker chromosome," which is an abnormal chromosome that does not correspond to any of the standard chromosomes in humans.

To break this down further, the presence of a marker chromosome can be concerning because it may indicate a structural abnormality in the chromosomes. Marker chromosomes can arise from various sources, including translocations, duplications, or other chromosomal rearrangements. The fact that 6 out of 140 cells showed this marker suggests that it is not present in all cells, which could imply that it is a mosaicism—meaning that some cells have the abnormality while others do not.

The next steps you are taking—having both parents undergo chromosomal analysis—are essential. This will help determine whether the marker chromosome is inherited from one of the parents or if it is a spontaneous mutation that occurred during the formation of the embryo. If it is a de novo mutation (not inherited), the implications may vary.
In terms of potential impacts, the presence of a marker chromosome can lead to a range of outcomes. Some individuals with marker chromosomes may be completely healthy and develop normally, while others may experience developmental delays, congenital anomalies, or other health issues. The specific effects depend on the nature of the marker chromosome and whether it disrupts any critical genes.

It's also important to consider the context of the pregnancy. If the marker chromosome is associated with a known syndrome or condition, further genetic counseling may be warranted. Genetic counselors can provide valuable insights into the risks of various outcomes based on the specific chromosomal findings and family history.

In summary, the presence of "47 XY + mar" indicates a chromosomal abnormality that requires further investigation. The next steps involving parental testing will help clarify the situation. Depending on the results, you may need to discuss potential implications for the pregnancy and the child's health with your healthcare provider or a genetic counselor. It's understandable to feel anxious during this time, but gathering more information will help you make informed decisions moving forward.

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