g2019: Genomic Press Release
On the week of 14 September 2008, Sergey Brin of Google announced
in his blog that he had at least one copy of the mutation G2019S in
the gene LRRK2 which may predispose him to develop Parkinson's
Disease, a neurodegenerative disorder affecting movement and
cognition. This was widely and sloppily reported in the press
including the New York Times and the Wall Street Journal, leading to
confusion about the role of genetic testing in Parkinson's
Disease.
Summary
The rare mutation G2019S of gene LRRK2 increases risk for Parkinson's Disease, a common disease of the nervous system.
Mutation Description
Scientists believe that LRRK2
mutations increase activity of the protein MAPK, causing neuron
death. At least six mutations of LRRK2 are known be correlated with
disease, most notably G2019S. Mutation probabilities vary by
ethnicity.
Probablity
The average person in the Western world has about a less than 1% probablity of having G2019S and about a 2% probability of having Parkinson's Disease.
Population
G2019S is known to be most relevant to populations of:
- People with family history of Parkinson's Disease because in this population:
- Parkinson's Disease is more probable
- Northern African Berbers because in this population:
- G2019S is much more probable
- G2019S is better studied in this population
- Ashkenazi Jews because in this population:
- G2019S is more probable
- G2019S is better studied in this population
- Men because in this population:
- Parkinson's Disease is more probable
- Elderly because in this population:
- Parkinson's Disease is more probable
Penetrance
People with G2019S have about a 25% chance of
Parkinson's Disease in their lifetime. This chance is greatly
influenced by other factors including ethnicity and family
history.
Prevalence
About 3% of people with Parkinson's Disease have G2019S.
Action
Regarding testing for G2019S in the Western world:
- (_) no known tests available
- (_) no tests commonly approved for medical use
- (_) test is patented and test is likely to be expensive (over $500 USD)
- (_) may be tested for $200 USD or less by an accredited lab
- (_) test is commonly covered by insurance
- (X) test is available on most SNP chips (Coriell, 23andMe)
- (X) test may be ordered by the public (non medical doctor)
- (X) test should be ordered by a doctor due to significant medical implications
- notes: 23andMe reports the G2019S related SNP in raw data but provides no interpretation, Coriell reporting is unknown
A positive test for G2019S:
- (X) is not used to diagnose Parkinson's Disease
- (_) confirms a clinical diagnosis of Parkinson's Disease
- (_) is a diagnosis of Parkinson's Disease, even without other symptoms
Clinical confidence for the medical application of G2019S testing regarding Parkinson's Disease is reserved because:
- (X) conflicting studies or unclear medical implications
- (_) insufficient predictive significance
- (_) poor or no support in scientific literature
- (_) only relevant to very specific at-risk populations
- (X) insufficient clinical application history
- (_) insufficient research or new study
- (X) limited or no actionable medical prevention
- (_) medical application has been soundly refuted
- (_) this is not a scientific claim
G2019S testing is medically applicable with at least reserved confidence for:
- clinical testing for familial cases of Parkinson's Disease with appropriate counseling
LRRK2 testing is medically applicable with at least reserved confidence for:
- clinical testing for familial cases of Parkinson's Disease with appropriate counseling
Moderator Notes
(Correction as of 4 Oct 08) 23andMe now reports G2019S in its
consumer-friendly report. Coriell's inclusion of G2019S in their test
is unknown.
Advising Physician Notes
This mutation which was reported in the popular press quotes a
penetrance rate of at most 80%. There are no caveats in most articles,
no mention of ethnicity or familial modulation of penetrance as
well. Most notably, an article from genetests.org also reports this
80% quote as if it were established fact. This is clearly not the
case.
Additional Sources
Disclaimers
- Mutations have very complex implications in the body that medical science does not yet understand.
- Fact template estimates are intentionally simplistic for better general public understanding and are not meant to be used as scientific literature.
- People known to be more likely to have a disease or trait associated with a mutation (e.g., because of family history) are more likely to discover that they have that mutation.
- Mutations occur with different frequencies in different populations.
- Genes describes RNA which describe proteins. Mutations in genes change those proteins. Changes in proteins change how the human body works.
- HelixGene's genomic reports are often written on short notice by volunteers and are best-effort works-in-progress.
- Consult a medical doctor of genetics if you have genetic or genomic related health concerns.
Submissions
If you are an expert with relevant creditential in genomics and you would like to help improve this document, submit revisions to this press release.
(more about expert creditentials).
If you would like to see a press release like this for another
gene, mutation, or effect, submit press release requests to
the press release attention queue.
