What DNA screening could hold for the future of healthcare

There’s some­thing thrilling about see­ing your genet­ic results for the first time. Just to gaze at the raw data – the swirling list of ade­nine (A), cyto­sine ©, gua­nine (G), and thymine (T) – is to see the very code for your phys­i­cal form. 

It’s a spir­i­tu­al moment – but it’s also a time to con­sid­er your health. DNA test­ing is now a main­stream health­care tool. Major providers inter­pret the find­ings to offer a long list of health­care insights. You’ll see at a glance if you have the genes for Tay-Sachs dis­ease or cys­tic fibro­sis.

There are many providers, includ­ing Helix, Bio-Syn­er­gy, and Neb­u­la Genomics. The biggest provider is 23andMe. Spit into a tube, post it and two weeks lat­er the 23andMe app offers around 100 health insights. These include 14 health genet­ic fac­tors, 45 reports on car­ri­er sta­tus – genes that may affect your chil­dren – and 37 traits such as the chances of hav­ing dim­ples, dan­druff, toe length, ear­ly hair loss and eye colour.

The health infor­ma­tion is rich – and some­times dis­turb­ing. DNA tests reveal the pres­ence of genet­ic vari­ants asso­ci­at­ed with chron­ic kid­ney dis­ease, hered­i­tary haemochro­mato­sis, and the dread­ed BRCA1 and 2 vari­ants for breast can­cer, among oth­ers. The actress Angeli­na Jolie under­went a pre­cau­tion­ary dou­ble mas­tec­to­my fol­low­ing a genet­ic test for breast can­cer. 

Testing limitations 

It’s a grow­ing trend. More than 10 mil­lion peo­ple have tak­en the 23andMe test alone. So should we all be tak­ing a DNA test? And if the results are so pro­found, why doesn’t the NHS offer such ser­vices?

“The bot­tom line is I haven’t done it myself,” says Sara Brown, a pro­fes­sor at the Uni­ver­si­ty of Edin­burgh spe­cial­is­ing in the genet­ic caus­es of dis­ease. “That should tell you some­thing about how high­ly I val­ue it. We’re all keen to have the equiv­a­lent of a crys­tal ball. So I can total­ly under­stand why peo­ple want to do it. But would I ever rec­om­mend it to a patient? I would­n’t.”

Brown explains that genet­ics is almost always too com­plex to be reduced to a set of results deliv­ered via an app. “The uncer­tain­ties make it real­ly dif­fi­cult to rec­om­mend for a spe­cif­ic ques­tion.” For exam­ple, look at the like­li­hood of con­tract­ing a dis­ease: “If you have an 80% risk, you’ve got a 20% like­li­hood you won’t get it. How then do you use that infor­ma­tion in your every­day life?” 

Fac­tor in lifestyle, envi­ron­ment, and umpteen oth­er genet­ic vari­ables, and the gap between genes and real-world out­comes become per­ilous­ly uncer­tain. “Very, very few dis­eases are a sin­gle gene,” she warns. “The vast, vast major­i­ty of human dis­eases are relat­ed to mul­ti­ple genet­ic effects inter­act­ing with each oth­er and also inter­act­ing with mul­ti­ple envi­ron­men­tal fac­tors.”

In fact, this is the same line tak­en by 23andMe. While the head­line results are clear­ly pre­sent­ed, each find­ing is linked to a wealth of fur­ther infor­ma­tion, filled with caveats and con­text. For exam­ple, the BRCA1 breast can­cer result states in bold writ­ing that while three genet­ic vari­ants are test­ed, “more than 1,000 vari­ants in the BRCA1 and BRCA2 genes are known to increase can­cer risk.” The lim­i­ta­tions of each health result are spelt out in clear bul­let points.

“Integri­ty is foun­da­tion­al to what we do,” says Dr L Okey Onye­jek­we Jr, vice pres­i­dent of health­care oper­a­tions and med­ical affairs at 23andMe. “That is why we reserve our­selves from going fur­ther than where sci­ence allows us to go.”

He says that for a nar­row range of dis­or­ders a genet­ic test deliv­ers high­ly com­pre­hen­sive infor­ma­tion. These are “sin­gle gene” dis­or­ders, such as alpha‑1 antit­rypsin and haemochro­mato­sis. But these “sin­gle gene, sin­gle dis­ease” exam­ples are rare. For oth­er con­di­tions, the com­pa­ny empha­sis­es the com­plex­i­ty of the job in hand. “For breast can­cer, the test is not con­clu­sive,” says Onye­jek­we Jr. “We don’t claim that it is. But it expands cov­er­age beyond what any tra­di­tion­al health care is cov­er­ing. So there is val­ue in that.”

Differing interpretations 

23andMe holds back on pub­lish­ing a range of poten­tial genet­ics links on the app as the med­ical research is under the con­fi­dence thresh­old. The com­pa­ny also pro­vides a trea­sure trove of infor­ma­tion, includ­ing links to orig­i­nal research, to help con­sumers under­stand the nuances of their results.

Oth­er providers are more adven­tur­ous. For exam­ple, epi­ge­net­ics is the sci­ence of how DNA is expressed. Providers such as Bio-Syn­er­gy claim to be able to cal­cu­late your bio­log­i­cal age com­pared to your chrono­log­i­cal age via epi­ge­net­ic test­ing. “It’s methy­la­tion,” says Brown, refer­ring to the epi­ge­net­ic mech­a­nism that reg­u­lates gene expres­sion. “And changes in methy­la­tion are up to 97% accu­rate at pre­dict­ing your bio­log­i­cal age, espe­cial­ly in younger peo­ple.” Smok­ing, for exam­ple, is vis­i­ble at the epi­ge­net­ic lev­el. So it’s an infor­ma­tive, sci­en­tif­i­cal­ly valid ser­vice.

The founder of Bio-Syn­er­gy, Daniel Her­man, is con­fi­dent his DNA and epi­ge­net­ic ser­vice pass­es the thresh­old of reli­a­bil­i­ty. “We demand a min­i­mum of five peer-reviewed pub­lished stud­ies before we incor­po­rate the sci­ence,” says Her­man, not­ing that the company’s head of nutrige­nomics, James Brown, has a PhD, while it also works with oth­er par­ties on the data.  

Providers push dif­fer­ent inter­pre­ta­tions depend­ing on their read­ing of the sci­ence. Bio-Syn­er­gy, for exam­ple, claims to be able to detect the like­li­hood of vit­a­min defi­cien­cies due to DNA, and sells vit­a­min drips to coun­ter­act this. This is more spec­u­la­tive, says Brown. “There are rare meta­bol­ic abnor­mal­i­ties,” she says, “but those are very rare and evi­dent through­out child­hood.” Bio-Syn­er­gy points to research to sup­port its claims. 

Scientific gains

Genet­ics is a com­plex area. Inter­pret­ing results beyond a nar­row range of dis­or­ders takes med­ical knowl­edge. Mer­ci­ful­ly, the main providers are keen to stress this, and if any­thing err on the side of cau­tion.

The real gain is for sci­ence as a whole. As anonymised DNA data is shared, along with sur­vey data col­lect­ed by test providers, sci­en­tists are reap­ing the ben­e­fits.

“I have used research data from 23andMe,” says Brown. “They share col­lect­ed genet­ic test­ing with researchers and I’ve ben­e­fit­ed from this.” Brown says the company’s num­bers “blew out of the water the num­bers from oth­er sources. Genet­ics is about num­bers, it’s about prob­a­bil­i­ties. We need big­ger and big­ger num­bers. And that’s what we get through resources such as 23andMe.”

For the indi­vid­ual, the results are fas­ci­nat­ing. But the big­ger pay­off is for sci­en­tists. Mas­sive datasets will unlock the secrets of the genome. Over time, the insights will get bet­ter and bet­ter. 

DNA tests are thus the future of health­care, just not quite in the way the con­sumer may envis­age.