Definition

Simpson-Golabi-Behmel syndrome (SGBS, OMIM #312870) is an X-linked macrosomia syndrome associated with malformations, reduced intelligence, and an increased risk of developing tumors.

Key Data

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Synonym
Genes GPC3 and GPC4 (not all genes are known yet)
Gene products Glypican-3 (GPC3) and glypican-4 (GPC4)
Function GPC3 and GPC4 are cell-surface-associated proteoglycans
Heredity X-chromosomal
Prevalence Rare
Genotype-phenotype correlation Involved are loss-of-function mutations without a known correlation.
Penetrance Presumably complete for male carriers of the mutation. Female carriers of the mutation may also be affected, but rarely.
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Diagnosis

Diagnosis

The diagnosis is made clinically and can be verified with a mutation analysis for patients with a defect in a known gene. As not all SGBS genes have been identified, genetic confirmation is not always feasible.

Differential Diagnoses

Clinical Presentation

Clinical Presentation

SGBS is characterized by prenatal and postnatal macrosomia, typical craniofacial changes (with macrocephaly, coarse facial features, macrostomia, macroglossia, palate abnormalities), and frequently a mild to severe intellectual disorder with or without structural brain changes. Other variable characteristics include an excessive number of nipples, rectal diastasis / umbilical hernia, diaphragmatic hernia, congenital heart defects, urogenital malformations, and gastrointestinal (GI) abnormalities. Moreover, there may also be skeletal abnormalities (vertebral fusion, rib abnormalities, hip dysplasia), hand abnormalities (large hands and postaxial polydactyly).

The following tumors have been described for patients with SGBS: Wilms tumors and nephroblastomatosis, hepatic tumors, and neuroblastoma. One child with SGBS and medulloblastoma has been described.

Therapeutic Considerations

Complex, multi-professional. There are no known special therapeutic considerations for treating cancer.

Surveillance Recommendations

Surveillance Recommendations

  • Early detection of a Wilms tumor with ultrasound, every 3 months until the age of 7

  • Early detection of hepatoblastoma with AFP and an abdominal ultrasound, every 3 months until age 4

Additional Information

Open Clinical Trials / Registries

There are currently no open clinical trials/registries for patients with Simpson-Golabi-Behmel syndrome that we can recommend to you for more information.

Support Groups

Unfortunately, we are as yet unaware of any existing support groups for patients with Simpson-Golabi-Behmel syndrome. We will add new information as it becomes available.