What physical feature is commonly associated with trisomy 18?

• A. Wide-set eyes
• B. Rocker-bottom feet
• C. Heart defects
• D. Long limbs

Answer: (B)

Rocker-bottom feet are a distinctive physical feature commonly associated with trisomy 18, also known as Edwards syndrome. This condition is characterized by a range of congenital anomalies and developmental delays due to an extra copy of chromosome 18. The term "rocker-bottom feet" describes a specific foot shape where the sole of the foot has a convex appearance, resembling the shape of a rocking chair. This deformity occurs due to malformations in the tendons and bones in the foot area during fetal development.

Rocker-bottom feet can be an important clinical marker when assessing an infant for potential chromosomal abnormalities. In the context of trisomy 18, this feature, along with other physical signs and symptoms such as growth delays, other deformities, and the presence of multiple organ defects, helps in making a diagnosis. Recognition of these features can aid in early intervention and management of the condition.