Which nomenclature is correct for a patient with Down syndrome with only trisomy 21 found?

In the context of cytogenetics, the correct nomenclature for a patient with Down syndrome due to trisomy 21, specifically when referring to a male patient, would typically start with the total number of chromosomes followed by the sex chromosome composition and the aneuploidy notation for the affected chromosome.

The notation 47,XY,+21 indicates that there are 47 chromosomes, the individual is male (XY), and there is an additional copy of chromosome 21, which is consistent with Down syndrome. The "c" in the option that includes it signifies that there is a cytogenetic notation following it, often used to indicate a specific variant or structural anomaly, and the brackets may further specify details about the chromosomes. However, in many contexts, when simply describing trisomy 21, the inclusion of such specific details is not necessary unless it pertains to a certain classification or additional findings.

Given that Down syndrome is characterized specifically by the presence of three copies of chromosome 21, the correct nomenclature would likely only need to indicate the presence of the third copy, without the additional details provided in option C. Therefore, while option C might provide extra information, the simpler and more universally recognized nomenclature would be seen in options like A