Syndromes with increased growth are listed in Table 12.1. Several, including Beckwith–Wiedemann syndrome, exhibit increased fetal growth with a high birth weight. Others, like cerebral gigantism or Sotos syndrome, are more remarkable for accelerated postnatal growth. Often there is neuropathology manifested by macrocephaly, dilated ventricles, structural brain anomalies, or early hypotonia. Predisposition to neoplasia accompanies many overgrowth disorders, exemplified by the occurrence of Wilms tumor in Beckwith–Wiedemann, Sotos, and hemihyperplasia syndromes. Accelerated skeletal maturation during childhood is also common, suggesting that growth factors acting early in life provide a common pathogenetic mechanism.

Overgrowth is also found in certain chromosomal disorders (e.g., fragile X syndrome), metabolic disorders (e.g., pseudohypoparathyroidism and the mucopolysaccharidoses), or hamartosis syndromes that also have predisposition to cancer (e.g., neurofibromatosis type 1). These disorders are discussed in other chapters. Obesity may also be considered a form of overgrowth, and increased caloric intake may produce increased statural growth and skeletal maturation during childhood. The growth acceleration induced by hyperphagia is usually transient, however, as exemplified by the short adult stature in Prader–Willi syndrome. Here syndromes with sustained growth acceleration due to unknown etiologies are discussed, including detailed consideration of Beckwith–Wiedemann syndrome.

Börjeson–Forssman–Lehmann syndrome

Börjeson–Forssman–Lehmann syndrome is an X-linked-recessive disorder that involves facial, skeletal, and genital anomalies in addition to mental disability. Overgrowth in this condition consists mainly of obesity, since 80% of patients eventually display short stature (Gorlin et al., 2001, pp. 426–7) Skeletal anomalies include thickened calvaria, narrow spinal canal, epiphyseal dysplasia, and short distal phalanges