Sotos Syndrome
Incidence
Unknown but a prevalence of 1 in 20-30,000 can be estimated based on over 200 reported cases. Sporadic occurrence with minimal recurrence risk for parents of affected children. Sotos syndrome is presumed to be autosomal dominant, with the majority of cases due to new mutations in the NSD1 gene on chromosome 5.
Clinical Characteristics
Pattern of manifestations including neonatal hypotonia, pre- and postnatal overgrowth, macrocephaly, characteristic facial appearance (frontal bossing, sparse frontal hair, down-slanting palpebral fissures, prominent jaw), accelerated bone age, and cognitive disability. Sporadic occurrence with minimal recurrence risk for parents of affected children; risks for affected individuals to transmit the syndrome are presumed low but not defined. The diagnosis of Sotos syndrome is clinical through noting the pattern of low muscle tone in infancy; the distinctive facial appearance with elongated head, prominent forehead, oval-shaped face, down-slanting palpebral fissures, and widely spaced eyes; the large hands and feet; the large birth weight and subsequent rapid growth. Medical complications include early feeding problems due to hypotonia with 40% requiring tube feedings. Problems relating to the early hypotonia may include strabismus, chronic otitis, constipation, clumsiness (with an increased frequency of fractures), and orthopedic problems such as flat feet or scoliosis. Eye anomalies (cataracts, strabismus, nystagmus, myopia); congenital heart defects (patent ductus arteriosus, septal defects); urological anomalies; and malignancies (neuroblastoma, hepatocellular carcinoma, non-Hodgkins lymphoma, leukemia and osteochondroma) also occur at increased frequency. Posterior spinal fusion was successful in one case of scoliosis (spinal curvature). Neurologic findings include paradoxically brisk deep tendon reflexes and brain anomalies including dilated cerebral ventricles, anomalies of the corpus callosum, and decreased brain matter around the ventricles (periventricular leukomalacia). The range of developmental quotients in 41 children was 40 to 129, with a mean of 78. No specific language deficits have been defined, but range of behavioral problems have been reported by teachers and parents including tantrums, withdrawal, sleep difficulties, and hyperactivity (38%). Behavioral problems may not exceed those of comparably delayed and over-sized children.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
It is a clinical diagnosis.There is no objective laboratory test to confirm the diagnosis. There is advanced bone age usually. Patients with clinical features suggestive of Sotos syndrome may be tested for microdeletions of chromosome 5 with mutation of the NSD1 gene.