What Can Be Learned From This Test
Testing is performed by sequencing exons 2 and 3 and the surrounding intronic regions of the HRAS gene. Sequencing of all coding exons can also be performed upon request. This assay will detect point mutations, small deletions and small insertions. It will not detect a partial or whole gene deletion or duplication.
HRAS is the only gene known to be associated with Costello syndrome. Sequence analysis of exon 2 detects a mutation in 80-90% of individuals with Costello syndrome. Mutations in other exons have also been reported. A negative test result does not rule out somatic mosaicism of an HRAS mutation, which has been described in individuals with Costello syndrome.
Costello syndrome is one of a group of related disorders caused by abnormal functioning of the Ras-mitogen-activated protein kinase (RAS/MapK) pathway. A negative HRAS test does not rule out all of these disorders, and additional testing may be indicated.
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 10-14 business days
CPT Codes and Cost
Full Gene Sequencing
Exons (2 & 3 Only)
Known Variant Testing