Tall stature and overgrowth syndromes — branching viva

Opening question

A six-week-old large-for-gestational-age infant has macroglossia, an umbilical hernia, and hemihyperplasia of the left leg. What is the most likely diagnosis, which molecular test confirms it and defines the tumour-risk subgroup, and what is the immediate and long-term surveillance plan? [2] [9]

Branch 1 — the genetics of overgrowth

Take the general principle. How do you decide whether a tall child is a normal variant or needs genetic testing, and which features drive the redistribution? Name the commonest syndromic overgrowth disorder, its responsible gene, and the shared biological theme that links the epigenetic overgrowth syndromes. [8] [6]

Branch 2 — the marfanoid adolescent

A tall, thin fifteen-year-old with long limbs and digits is referred for assessment. What is your differential, how do you distinguish Marfan syndrome from homocystinuria, and what surveillance does the Marfan diagnosis trigger? Why does the direction of the lens dislocation matter, and what is the cardiovascular threat that the annual echocardiogram exists to prevent? [6]

Branch 3 — the tall-now-short-later paradox

A seven-year-old girl is the tallest in her class and has begun developing breasts. Explain the paradox by which precocious puberty makes a child tall now but short at final height, and name the intervention that changes the trajectory. How does this contrast with the eunuchoid tall stature of delayed puberty and Klinefelter syndrome? [6]

Closing — the general approach

In one sentence, what is the principle of the tall-child assessment, and why is the redistribution — the structured examination for dysmorphism, proportions, asymmetry, and development — the skill that separates the reassured majority from the investigated minority? [8] [6]