When assessing a newborn, the presence of a single palmar crease should be considered:

• A. A normal variant
• B. Diagnostic for Down syndrome
• C. Suggestive of Down syndrome if accompanied by other dysmorphic features
• D. Pathognomonic for Down syndrome

Answer: (C)

A single palmar crease is a non-specific finding in newborns. It occurs more often in babies with Down syndrome, but it can also appear in healthy infants, so it isn’t diagnostic on its own. It becomes suggestive of Down syndrome when it appears alongside other dysmorphic features such as hypotonia, upslanting palpebral fissures, flat midface, epicanthal folds, or brushfield spots; in that setting, it supports the need for further evaluation or genetic testing. If no other features are present, it can be a normal variant.