Editor—We present the clinical histories and physical findings in two unrelated, severely mentally retarded males, now 14 and 11 years old.

Patient 1, a male, was born as the second and youngest child of healthy, unrelated Flemish parents with normal family histories. Pregnancy and delivery at 38 weeks' gestation were normal. Birth weight was 3200 g, length 47 cm, and head circumference 34 cm. Immediately after birth a number of dysmorphic signs were noted by the paediatrician, including facial oedema with ptosis of both eyelids, temporal flattening, hypertelorism, webbed neck, broad thorax with widely spaced, small, inverted nipples, shallow scrotum, and testes in the inguinal canal. The hands were broad and short with permanent oedema on the dorsum and the skin was loose and hyperextensible, especially on the arms. The diagnosis of Noonan syndrome was considered. Cardiac and renal echography was normal. Prometaphase chromosome studies on a peripheral blood lymphocyte culture showed a 46,XY normal male karyotype after G and R banding. Except for excessive weight loss, down to 2600 g, no major problems were noted in the neonatal period. In the first two years of life mild psychomotor retardation was noted with discrete hypertonia of the lower limbs. He started to walk without support on tiptoes at the age of 19 months. At the age of 2 years mental age was 15 months on the Bayley Developmental Scale.

At the age of 3 years, the first episodes of epileptic attacks were noted with variable clinical presentation of the grand mal, petit mal, and myoclonic types. Seizures were resistant to anti-epileptic therapy and, from that age onwards, severe behavioural problems were noted with chaotic and destructive tantrums. …