Prevention Genetics #428 FGFR3 Gene

Message
http://preventiongenetics.com/clinical-dna-testing/requisition-forms/


Test Code
426


Preferred Specimen
Whole Blood 5 mL


Minimum Volume
2 mL


Other Acceptable Specimens
"ACD (yellow top tube). (DNA, Cell Culture) DNA
(Delivery accepted Monday - Saturday)

Send in a screw cap tube at least 15 µg of purified DNA at a concentration of at least 20 µg/ml. For tests involving the sequencing of more than three genes, send an additional 5 µg DNA per gene. DNA may be shipped at room temperature.
Label the tube with the DNA concentration as well as the patient name, date of birth, and/or ID number.
Specify the composition of the solute.
We only accept genomic DNA for testing. We do not accept products of whole genome amplification reactions or other amplification reactions.


Cell Culture
(Delivery accepted Monday - Thursday)

PreventionGenetics should be notified in advance of arrival of a cell culture.
Ship at least two T25 flasks of confluent cells.
Label the flasks with the patient name, date of birth, and/or ID number.
We do not culture cells."


Instructions
For small babies, we require a minimum of 1 ml of blood


Transport Container
EDTA (purple top tube)


Transport Temperature
room temperature in an insulated container. Do not freeze blood. During hot weather, include a frozen ice pack in the shipping container. Place a paper towel or other thin material between the ice pack and the blood tube. In cold we


Specimen Stability
"At room temperature, blood specimen is good for up to 48 hours.
If refrigerated, blood specimen is good for up to one week
"


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Frozen, insufficient quantity


Setup Schedule
Delivery accepted Monday - Saturday


Report Available
Maximum of 40 days, although many tests are completed in 2-3 weeks


Limitations
"In exons where our sequencing did not reveal any variation between the two alleles, we cannot be certain that we were able to PCR amplify both of the patient’s alleles. Occasionally, a patient may carry an allele which does not amplify, due for example to a deletion or a large insertion. In these cases, the report contains no information about the second allele.

Similarly, our sequencing tests have almost no power to detect duplications, triplications, etc. of the gene sequences.

In most cases, only the indicated exons and roughly 20 bp of flanking non-coding sequence on each side are analyzed. Test reports contain little or no information about other portions of the gene, including many regulatory regions.

In nearly all cases, we are unable to determine the phase of sequence variants. In particular, when we find two likely causative mutations for recessive disorders, we cannot be certain that the mutations are on different alleles.

Our ability to detect minor sequence variants, due for example to somatic mosaicism is limited. Sequence variants that are present in less than 50% of the patient’s nucleated cells may not be detected.

Runs of mononucleotide repeats (eg (A)n or (T)n) with n >8 in the reference sequence are generally not analyzed because of strand slippage during PCR and cycle sequencing.

Unless otherwise indicated, the sequence data that we report are based on DNA isolated from a specific tissue (usually leukocytes). Test reports contain no information about gene sequences in other tissues."


Clinical Significance
Hypochondroplasia is inherited in an autosomal dominant manner. The majority of new cases result from a de novo mutation. FGFR3 is the only gene known to be associated with hypochondroplasia; however, genetic heterogeneity is suspected. Two recurrent FGFR3 mutations (c.1620C>A and c.1620C>G) resulting in p.Asn540Lys in exon 13 that encodes the ATP-binding segment of the tyrosine kinase domain have been shown to be common cause of hypochondroplasia (Bellus et al. Nat Genet 10:357–359, 1995; Prinos et al. Hum Mol Genet 4:2097–2101, 1995). Sequence analysis of FGFR3 exons 7, 9, 10, 13, and 15 detects other rare FGFR3 mutations associated with hypochondroplasia. FGFR3 gene encodes fibroblast growth factor receptor-3, a member of the FGFR family. Like all of the FGFRs, FGFR3 is a membrane-spanning tyrosine kinase receptor with an extracellular ligand-binding domain consisting of three immunoglobulin subdomains, a transmembrane domain, and a split intracellular tyrosine kinase domain (Green et al. Bioessays 18:639–646. 1996).




The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.