Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is characterized by X-linked inheritance; pre and postnatal macrosomia; characteristic facial features, including macrocephaly, coarse facies, and palate abnormalities; mild to severe intellectual disability; and multiple congenital anomalies, including congenital heart defects, supernumerary nipples, and diaphragmatic hernia. Additionally, individuals with SGBS1 are at increased risk for embryonal tumors. Female carriers can have manifestations of SBGS1 due to skewed X chromosome inactivation.
Mutations in the GPC3 and the GPC4 genes (Xq26) cause SGBS1. Please note that this test is only for the GPC3 gene.
For patients with suspected SGBS1, sequence analysis is recommended as the first step in mutation identification. For patients in whom mutations are not identified by full gene sequencing, deletion/duplication analysis is appropriate.
- Confirmation of a clinical diagnosis of Simpson-Golabi-Behmel syndrome type 1 in an individual in whom sequence analysis was negative.
- Carrier testing in adults with a family history of Simpson-Golabi-Behmel syndrome type 1 in whom sequence analysis was negative.
Please note that a "backbone" of probes across the entire genome are included on the array for analytical and quality control purposes. Rarely, off-target copy number variants causative of disease may be identified that may or may not be related to the patient's phenotype. Only known pathogenic off-target copy number variants will be reported. Off-target copy number variants of unknown clinical significance will not be reported.
Submit only 1 of the following specimen types
Preferred specimen type: Whole Blood
Type: Whole Blood
Specimen Requirements:In EDTA (purple top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml
Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample within 5 days of collection at room temperature with overnight delivery.
Specimen Requirements:OrageneTM Saliva Collection kit (available through EGL) used according to manufacturer instructions.
Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.
- Sequence analysis of the GPC3 gene is available and is required before deletion/duplication analysis.
- Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
- Prenatal testing is available only for known familial mutations to individuals who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.
- X-Linked Intellectual Disability panels are available for 30, 60, and 90 genes.