Prader-Willi syndrome is characterised by massive obesity, short stature, small hands and feet, a distinctive face with almond-shaped eyes and postnatal hypotonia following poor foetal activity (Fig. 13.24).
Behavioural abnormalities in this syndrome include development delay and emotional instability. There is an association of Prader-Willi syndrome with delayed puberty due to hypothalamic dysfunction. Affected boys may appear to have a microphallus, partly due to the increased fat pad at the base of the phallus which ΓÇÿburiesΓÇÖ the penis, although hypogonadotrophic hypogonadism may also be present and cause decreased phallic size. Carbohydrate intolerance occurs in Prader-Willi syndrome, possibly related to the massive obesity. Up to fifty per cent of affected patients have an interstitial deletion of the long arm of chromosome 15 (Del 15) (Q11ΓÇôQ12).
