Ge­netic test­ing gets ac­cu­racy boost

Lab test may iden­tify dan­ger­ous gene mu­ta­tions, study finds

The Recorder & Times (Brockville) - - LIFE - MAL­COLM RIT­TER

NEW YORK — Sci­en­tists say they’ve found a new way to help de­ter­mine whether spe­cific ge­netic ab­nor­mal­i­ties are likely to make peo­ple sick, a step to­ward avoid­ing a vex­ing un­cer­tainty that can sur­round DNA test re­sults.

Re­searchers used ge­netic en­gi­neer­ing to cre­ate thou­sands of tiny vari­a­tions in a gene linked to breast cancer, and tested each one in a lab to pre­dict whether it would pro­mote the dis­ease if it ap­peared in a per­son.

When those pre­dic­tions were checked against what sci­en­tists al­ready knew about the BRCA1 gene, “we were very ac­cu­rate,” said Lea Starita of the Brot­man Baty In­sti­tute for Pre­ci­sion Medicine in Seat­tle.

The tech­nique, which she and her col­leagues hope to ex­tend to other genes, is aimed at eas­ing a frus­trat­ing prob­lem in ge­netic test­ing. Some­times those tests re­veal an ab­nor­mal­ity in a gene linked to the dis­ease, but no­body knows whether that par­tic­u­lar quirk is haz­ardous. It’s called a “vari­ant of un­cer­tain sig­nif­i­cance,” or VUS.

Such a re­sult can cause anx­i­ety and worse: Ex­perts talk about women who’ve had breasts re­moved af­ter learn­ing they had a VUS in a gene linked to breast cancer, only to find out years later that fur­ther re­search showed their vari­ants were harm­less.

The new work aimed to iden­tify tiny vari­ants in the BRCA1 gene’s DNA code that keep it from work­ing. Mu­ta­tions that dis­able this gene greatly raise the risk of breast and ovar­ian cancer.

Re­sults were pub­lished Wed­nes­day by the jour­nal Na­ture.

Re­searchers cre­ated nearly 4,000 tiny vari­a­tions in key sec­tions of the gene. Then they tested whether each vari­ant crip­pled the gene within cells that die when BRCA1 isn’t work­ing. That let them pre­dict which vari­a­tions would pro­mote cancer if found in a per­son.

Re­searchers plan to ex­pand the test to other genes that can pre­dis­pose peo­ple to cancer, and other dis­eases.

Go­ing be­yond cancer genes would raise the dif­fi­cult chal­lenge of find­ing ap­pro­pri­ate lab tests, said Jay Shen­dure of the Baty in­sti­tute.

The ap­proach al­lows test­ing vari­a­tions be­fore they’re even seen in peo­ple, so their sig­nif­i­cance can be im­me­di­ately known once they show up for the first time in a ge­netic test, he said.

Re­sults look promis­ing for re­solv­ing VUS in BRCA1 when used along with other in­for­ma­tion, said Heidi Rehm of Bos­ton’s Mas­sachusetts Gen­eral Hospi­tal and the Broad In­sti­tute in Cam­bridge, Mas­sachusetts.

BRCA1 has a low rate of VUS test re­sults, but Rehm said the gen­eral ap­proach could be ap­plied to some other genes.

More re­search is needed to con­firm the new ap­proach as use­ful for BRCA1 and other genes.

“I re­ally, re­ally hope” its prom­ise will be con­firmed, said Julie Eg­ging­ton, CEO of the Cen­ter for Ge­nomic In­ter­pre­ta­tion in Sandy, Utah.

EWA KRAWCZYK/NA­TIONAL CANCER IN­STI­TUTE

Flu­o­res­cent-col­ored mi­cro­scope im­age made avail­able by the Na­tional In­sti­tutes of Health in Septem­ber 2016 shows a cul­ture of hu­man breast cancer cells. On Wed­nes­day, sci­en­tists re­ported they’ve found a new way to de­ter­mine whether spe­cific ge­netic ab­nor­mal­i­ties are likely to make peo­ple sick, a step to­ward avoid­ing a vex­ing un­cer­tainty that can sur­round DNA test re­sults.

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