LETTER TO JMG Familial Sotos syndrome is caused by a novel 1 bp deletion of the NSD1 gene

Sotos syndrome (SS) or cerebral gigantism (OMIM*117550) is characterised by excessive growth, advancedbone age, typical facial gestalt, and developmental delay.1 2 In infancy growth is rapid, but settles down above the>97th centile in early childhood3 4 and tends to follow this during childhood. The adult height remains close to normal.4 The hands and feet are large. The facial gestalt is very charac-teristic during childhood with macrocephaly (>97th centile), frontal bossing, prognathism, hypertelorism, and antimongol-oid slant of the palpebral fissures. With increasing age, the face gradually lengthens, the jaw becomes more prominent, and macrocephaly is no longer pronounced.5 6 Neurological features are variable and include hypotonia and delay inmotor and language development, with a tendency for improvement with age.1 2 5–9 Familial SS is rare. Only 17 families have been reported, most of which show an autosomal dominant mode of inheritance.5 6 10–19 Recent advances have shown a molecular genetic basis fo