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:

Genes (1)

Your search may have returned a result for a gene alias. Click here for a full list of genes and their aliases.

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.

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

Listed below are EGL's preferred sample criteria. For any questions, 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
Whole Blood (EDTA)
WBP

Requirements
EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 72 hours of collection. Do not freeze.
DNA, Isolated
DNA

Requirements
Microtainer
3µg
Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample 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.
  • 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.

How to Order