DNA Testing

DNA testing is a relatively recent and the only conclusive way to diagnose Noonan Syndrome. To date, there are seven known genes associated with the syndrome: PTPN11 (Documented in 2001), KRAS (2006), SOS1 (2007), RAF1 (2007), BRAF (2009), NRAS (2010) and MEK1

The general process is as follows:

  1. Preliminary diagnosis given by geneticist and DNA testing for confirmation recommended
  2. Consent form completed. This form gives approval to the medical facility to release private and confidential medical information to the Ontario Ministry of Health (MoH) to secure the necessary funding for the Out of Country DNA testing (see side bar).
  3. Blood sample drawn and held by medical facility pending MoH approval
    Timing: MoH approval generally takes 3 – 4 weeks
  4. Sample sent to lab for testing
  5. Tiered test completed – Tiered testing looks at each gene area in sequence starting with the most likely gene first, testing each subsequent gene based on the frequency of occurrence. Testing continues until a likely gene mutation is located or all currently known areas are eliminated.
    Timing: DNA testing through all four genes averages 6 – 8 weeks.

  6. If a gene mutation is discovered, the option exists for the parents to be tested as well. The process is the same except the lab will test for the specific mutation only. If the parents’ tests also return positive then other children within the family can also be tested.
    [To test or not to test? Share your thoughts on the online forum]

    Important Note: A negative DNA test result for the four known genes does not eliminate a Noonan Syndrome diagnosis. With the remaining 10 – 15% currently unassociated causes, the gene or series of genes may have yet to be identified.
 
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