Which of the following traits is not visible in a person with Down syndrome?

Step 1: Analyze the question We are asked to find the trait that is NOT associated with Down syndrome (Trisomy 21). This is an "exception" question, so we look for the odd one out.

Step 2: Concept Down syndrome is a chromosomal disorder caused by an extra copy of chromosome 21 (the person has 47 chromosomes instead of 46). This usually happens through non-disjunction during gamete formation.

Common features include:

• Short neck
• Small stature (short height)
• Upward-slanting eyes (slant eyes) with a skin fold at the inner corner
• Flattened face and small ears
• Hypotonia, which means low muscle tone (floppy muscles)
• Intellectual disability and a single crease across the palm

Step 3: Check each option

• A. Short neck: Typical of Down syndrome. ✔
• B. High muscle tone: Down syndrome causes low muscle tone (hypotonia), not high. ✘ This is the exception.
• C. Small stature: Typical of Down syndrome. ✔
• D. Slant eyes: Typical of Down syndrome. ✔

Step 4: Answer The trait that is not seen in a person with Down syndrome is high muscle tone, so the correct option is B.

Exam tip: Remember "Down = Down tone." Down syndrome means low muscle tone (hypotonia). Also link it with Trisomy 21, and don't confuse it with Turner syndrome (XO, short stature and webbed neck in females) or Klinefelter syndrome (XXY, tall males).