Cohen Syndrome: VPS13B Gene Deletion/Duplication
Condition Description
Cohen syndrome, an autosomal recessive condition, is characterized by failure to thrive, obesity, hypotonia, and developmental delays. Common features of Cohen syndrome include retinal dystrophy that appears by mid-childhood, progressive high myopia, acquired microcephaly, non-progressive intellectual disability, global developmental delay, hypotonia, and joint hypermobility. Less common features include short stature, small or narrow hands and feet, truncal obesity (which appears during or after mid-childhood), friendly disposition, and non-cyclic granulocytopenia.
Mutations in the VPS13B gene (8q22-q23) (also known as COH1) cause Cohen syndrome and can be detected in 88% of individuals with typical clinical features of Cohen syndrome.
References:
Mutations in the VPS13B gene (8q22-q23) (also known as COH1) cause Cohen syndrome and can be detected in 88% of individuals with typical clinical features of Cohen syndrome.
References:
- GeneReviews
- OMIM #216550: Cohen syndrome
- OMIM #607817: VSP13B gene
Genes (1)
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Indications
This test is indicated for:
- Confirmation of a clinical diagnosis of Cohen syndrome in an individual in whom sequence analysis was negative.
- Carrier testing in adults with a family history of Cohen syndrome in whom sequence analysis was negative.
Methodology
DNA isolated from peripheral blood is hybridized to a CGH array to detect deletions and duplications. The targeted CGH array has overlapping probes which cover the entire genomic region.
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.
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.
Detection
Detection is limited to duplications and deletions. The CGH array will not detect point or intronic mutations. Results of molecular analysis must be interpreted in the context of the patient's clinical and/or biochemical phenotype.
Specimen Requirements
When sample fails to meet the acceptable criteria, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (eglgc@egl-eurofins.com).
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.
Type: Saliva
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.
Special Instructions
Sequence analysis is required before deletion/duplication analysis by targeted CGH array. If sequencing is performed outside of EGL Genetics, please submit a copy of the sequencing report with the test requisition.
Related Tests
- Sequence analysis of the VPS13B 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.