The HRAS gene is the only gene (11p15.5) currently known to be associated with Costello syndrome. In patients with a clinical diagnosis of Costello syndrome, 80-90% of mutations in the HRAS gene can be identified. Mutations in the HRAS gene are inherited in an autosomal dominant manner; however most individuals with Costello syndrome has a de novo mutation. Please note that the HRAS gene is part of the Ras/MAKP pathway and other syndromes should be considered as alternative diagnoses if an HRAS mutation is not identified.
For patients with suspected Costello syndrome, 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 Costello syndrome.
- Carrier testing in adults with a family history of Costello syndrome.
Analytical Sensitivity: ~99%
Submit only 1 of the following specimen types
Preferred specimen type: Whole Blood
Type: Whole Blood
Specimen Requirements:In EDTA (purple top) or ACD (yellow 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.
- Deletion/duplication analysis of the HRAS gene by CGH array is available for those individuals in whom sequence analysis is negative.
- Please note that the HRAS gene is part of the Ras/MAKP pathway and other syndromes should be considered as alternative diagnoses if an HRAS mutation is not identified.
- 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.