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Be Careful of Direct-To-Consumer Genetic Tests

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123Donna View Drop Down
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    Posted: Feb 16 2021 at 6:14pm
Common genetic test often wrong when identifying rare disease-causing variants such as BRCA1 and BRCA2, study says:
A genetic test used to detect common traits many people share is not reliable in identifying rare disease-causing variations, such as those that can predict breast and ovarian cancer, a new study has found.
The SNP test, which stands for "single nucleotide polymorphism," is used by direct-to-consumer DNA and ancestry companies to identify common traits such as eye color, height and proclivity toward cheek dimples and dandruff, to name a few.
But when SNP tests are applied to identifying rare mutations that contribute to disease, the study found only 16% of nearly 5,000 rare mutations could be confirmed by more stringent DNA sequencing tools.
When applied to mutations in BRCA1 and BRCA2 genes, which can predict a high risk for breast and ovarian cancer, the SNP test only had a positive predictive value of 4.2%, according to the study published Monday in the journal BMJ Open Access.
"It seems that a very rare, disease-causing variant detected using a SNP chip is more likely to be wrong than right," said study co-author Caroline Wright, a professor of genomic medicine at the University of Exeter in the United Kingdom, and co-author Michael Weedon, an associate professor in bioinformatics and human genetics at the University of Exeter, in an accompanying commentary to the study.
"The implications of our findings are very simple: SNP chips perform poorly for detecting very rare genetic variants and the results should never be used to guide a patient's medical care, unless they have been validated," added co-author Leigh Jackson, a lecturer in genomic medicine at Exeter, in a separate press statement. . . .

. . . .Both Ancestry and 23andMe spokespeople told CNN they echo those concerns.
"We caution all of our customers who wish to use their unvalidated raw genotypic data to not do so for any health purposes," Spatafore said.
On their website, 23andMe tells its users that if they decide to download their raw data, they should "take caution in uploading your data to any third party applications or any service outside of your 23andMe account.
"Raw data should not be used for medical purposes and we do not recommend the use of third party services that claim to interpret raw data to provide health information."

DX IDC TNBC 6/09 age 49, Stage 1,Grade 3, 1.5cm,0/5Nodes,KI-67 48%,BRCA-,6/09bi-mx, recon, T/C X4(9/09)
11/10 Recur IM node, Gem,Carb,Iniparib 12/10,MRI NED 2/11,IMRT Radsx40,CT NED11/13,MRI NED3/15

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SagePatientAdvocates View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SagePatientAdvocates Quote  Post ReplyReply Direct Link To This Post Posted: Feb 17 2021 at 8:18am
Dear Donna,

Excellent thread. Thanks for bringing to our attention.


I am a BRCA1+ grandson, son and father of women affected by breast/oc-my daughter inherited mutation from me, and at 36, was dx 2004 TNBC I am a volunteer patient advocate with SAGE Patient Advocates
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