Which statement about a single palmar crease is true?

• A. It is always diagnostic for Down syndrome
• B. It never relates to Down syndrome
• C. It is suggestive of Down syndrome if accompanied by other dysmorphic features
• D. It confirms chromosomal abnormality

Answer: (C)

A single transverse palmar crease is a non-specific physical finding. It occurs more often in individuals with Down syndrome, but it is not unique to them and can be seen in healthy people as well. The important point is that this crease by itself does not diagnose a chromosomal disorder; its significance rises when it appears alongside other dysmorphic features or clinical concerns.

In Down syndrome, many babies have additional signs such as hypotonia, upslanting palpebral fissures, epicanthal folds, flat facial profile, and certain growth patterns. When a single palmar crease is present with these other features, the overall picture raises suspicion and may lead to diagnostic testing like karyotype or genetic microarray. If the crease appears alone, without other signs, it is not enough to make or confirm a chromosomal diagnosis.

So the correct idea is that a single palmar crease is suggestive of Down syndrome only in the context of other dysmorphic features; it does not by itself confirm the diagnosis or indicate a chromosomal abnormality.