Cerebral gigantism. Triad of findings helpful in diagnosis

A case of Sotos syndrome (cerebral gigantism) and psychosis

Sotos syndrome, or cerebral gigantism, is a syndrome of accelerated growth during early childhood, and a number of craniofacial and other physical abnormalities are commonly present. Behavioral and psychiatric manifestations of the disorder include attention deficits, aggressiveness, and social inhibition. The authors describe a case of psychosis that developed in a patient with Sotos syndrome.

Plasma insulin-like growth factors (IGFs), IGF-Binding proteins (IGFBPs), acid-labile subunit (ALS) and IGFBP-3 proteolysis in individuals with clinical characteristics of Sotos syndrome

OBJECTIVE

Sotos syndrome is an overgrowth syndrome of poorly understood aetiology. We investigated whether this syndrome is related to alterations in plasma insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), acid-labile subunit (ALS) and serum IGFBP-3 proteolysis.

DESIGN

Based on clinical criteria, 32 patients with clinical characteristics of Sotos syndrome (median age 8.4 years, range 1.8-48.4) were categorised into three groups: typical (n = 10, group 1), dubious (n = 12, group 2) and atypical (n = 10, group 3). Blood samples were obtained from 29 patients.

MEASUREMENTS

Plasma IGF-I, IGF-II, E-II (pro-IGF-II and E-domain fragments), IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6 and ALS were measured by specific radioimmunoassays (RIAs). Except for E-II immunoreactivity, the concentrations were compared with those of age references, and expressed as standard deviation scores (SDS). IGFBP-3 proteolysis was assessed by incubation of serum with [125I]-IGFBP-3, followed by gel electrophoresis and was then compared with that in normal serum and third trimester pregnancy serum.

RESULTS

Patients in group 1 showed significantly reduced plasma levels of IGF-II (median -0.9 SDS; p = 0.01), IGFBP-4 (-0.5 SDS; p = 0.02) and IGFBP-3 (-1.0 SDS; p = 0.01). Mean IGFBP-3 proteolysis was higher than in normal standard serum (61% vs 37%; p < 0.01) but lower than in third trimester pregnancy serum (94%; p < 0.01). Plasma IGF-I showed a tendency towards low values (median -0.9 SDS; p = 0.09), IGFBP-6 and ALS a tendency towards elevated levels (median values +0.8 SDS; p = 0.07 and +2.3 SDS; p = 0.09), and IGFBP-2 was normal. The mean value of E-II immunoreactivity was 8.7 nmol/l, similar to that in pooled normal plasma (8.6 nmol/l). Plasma and serum parameters in groups 2 and 3 were similar to reference values with the exception of plasma IGFBP-3 (in groups 2 and 3 median < or = -1.1 SDS; p < or = 0.02) and ALS (in group 3 median +1.3 SDS; p < 0.01).

CONCLUSIONS

Patients with typical Sotos syndrome show low plasma IGF-II, IGFBP-3, IGFBP-4, and increased proteolysis of IGFBP-3 in serum. The extent to which these findings are associated with the pathophysiology of Sotos syndrome remains uncertain.

Genetics of Sotos syndrome

PURPOSE OF REVIEW

Sotos syndrome (SoS) (OMIM #117550) is a childhood overgrowth syndrome characterized by excessive growth, distinctive craniofacial features, developmental delay, and advanced bone age. Recently, haploinsufficiency of the NSD1 gene has been identified as the major cause of SoS, with intragenic mutations or submicroscopic microdeletions being found in about 60 to 75% of clinically diagnosed patients with SoS.

RECENT FINDINGS

Recent reports provided much information about the genetic background of SoS, the NSD gene family, and genotype-phenotype correlation. They also added new perspectives in the discussion about a possible association between SoS and neoplasia.

SUMMARY

This review focuses on recent genetic developments in SoS. Clinical features and associated anomalies are reviewed in relation to possible functional roles of NSD1. Genotype-phenotype correlation between patients with SoS harboring either intragenic mutations or microdeletions is discussed as well as their implication for possible revision of the diagnostic criteria of SoS. Furthermore, future prospects in genetic research of SoS are presented.

Sotos syndrome (cerebral gigantism): a clinical and radiological study of 14 cases from Saudi Arabia

Fourteen children (of Arab ethnic origin) with Sotos syndrome are described. They were referred to King Khalid University Hospital, Riyadh between July 1992 and June 1997. Their phenotypic characteristics were compared with established diagnostic criteria. There was a male:female ratio of 1.3:1 and a high rate of consanguinity (36%) among parents. At birth, 54% were large and about one-third showed increased height and occipitofrontal head circumference (OFHC). The neonatal histories revealed respiratory and feeding problems in 21%, followed later by delayed motor milestones and speech development in 57%. During childhood, weight, height and OFHC increased further to > 97th centile in 71%, 71% and 93%, respectively. A seizure disorder affected 43%, and 75% had mental retardation (IQ < 70). A non-specific EEG abnormality was found in half of those with seizures. Cranial CT/MRI showed ventricular dilatation in 15% and one patient had corpus callosum dysgenesis. Abdominal ultrasound revealed hydronephrosis in two patients. Radiological cephalometric measurements showed relative prognathism in cases of Sotos syndrome compared with controls (p = 0.003). The study highlights the importance of considering Sotos syndrome in children who present with psychomotor delay.

Sotos Syndrome

Sotos syndrome is characterized by high birth length, rapid bone growth, distinctive facial features, and possible verbal and motor delays. It may be the result of an autosomal dominant inheritance pattern and it is more common in males than females. Developmental deficits or specific learning problems may be present. Speech and language delays may occur, although reported cases vary from normal development to severe delays. Hoarse voice is not uncommon.

Psychological characteristics of Sotos syndrome

A preliminary investigation of the psychological characteristics of 16 children aged between five and 15 years who met the strict diagnostic criteria for Sotos syndrome demonstrated that, while cognitive abilities vary, there are behavioural patterns that are characteristic of the disorder. The children were reported to have high rates of behavioural disturbance at home, particularly tantrums, destructiveness, social withdrawal, and eating and sleeping difficulties. The children were reported to present fewer problems in the school environment. Other difficulties expressed by parents are also described and quantified.

Sotos syndrome

Images

Familial Sotos syndrome (cerebral gigantism): craniofacial and psychological characteristics

Most reported cases of Sotos syndrome are sporadic, but autosomal dominant and recessive inheritance patterns have been suggested. Ascertainment of a two-generation family through a 7-year-old proposita with a learning disability allowed the relatively unbiased study of two affected relatives. Developmental delay was not pronounced in the patient's mother or sister; craniofacial characteristics at variance with the characteristic description included acrocephaly and maxillary prominence. Steepness of the anterior cranial base angle and protrusion of the middle and lower face, shown in all three patients by cephalometric radiographs, deserve further evaluation as diagnostic criteria.

Dominant inheritance of cerebral gigantism

Cerebral gigantism is a syndrome consisting of characteristic dysmorphic features, accelerated growth in early childhood, and variable degrees of mental retardation. Its etiology and pathogenesis have not been defined. Three families are presented with multiple affected members. The vertical transmission of the trait and equal expression in both sexes in these families indicates a genetic etiology with a dominant pattern of inheritance, probably autosomal. As in previously reported cases, extensive endocrine evaluation failed to define the pathogenesis of the accelerated growth present in this disorder.