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The EconomistMarch 14th 2020 Technology Quarterly |Personalised medicine 3

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eenanizaris 42 yearsold,a professorofbusinessstudiesand

just122cmtall.Theendsofherbonesaresoftandpliable:on

anx-raytheylookfrayed,likeoldpaintbrushes.Duringherchild-

hoodandadolescenceinDubaishewasoperatedon 30 times.The

sourceofherproblemremaineda mystery.In2010,afterthreede-

cadesof wondering,shefinallyreceived adiagnosis:Jansen’s

MetaphysealChondrodysplasia,aconditionfirstrecognisedin

the1930s.Herproblemsstemfroma brokencopyofjustoneofher

20,000genes.

DrNizarisinsomewaysveryunusual.Fewerthanonein200m

peoplehavethemutationtothePTH1RgenethatcausesJansen’s

disease.Inotherwayssheislikeeveryoneelse.Althoughfewpeo-

plehavea defectasdebilitating,everyone’shealth,andill-health,

istiedtothecontentsoftheirgenomes.Allgenomescontainar-

rangementsofgenesthatmakepsychologicaldisorders,cancers,

dementiasorcirculatorydiseaseseithermoreofa problemorless

ofone.Everyonehasgenesthatmakethembetterorworseatme-

tabolisingdrugs,moreorlesslikelytobenefitfromspecificforms

ofexercise,betterabletodigestsomefoodsthanothers.

Thesamearrangementwillneverbeseentwice.Thoughfor

identicaltwinsthedifferencesaretheheightofsubtlety,eachof

the7.5bnhumangenomessharingtheplanetisunique.Thatirre-

duciblediversityrepresentsa challengetomanyofthe20thcen-

tury’sgreatestmedicaladvances,whichwerebasedona one-size-

fits-allapproach.Personalisingmedicineisanenticingopportu-

nityforimprovement.

Gooddoctorshavealwaystreatedtheirpatientsasindividuals.

Inthe20thcenturybloodtests,x-rays,bodyscansandotherdiag-

nostictoolsmadethespecificsofeachpatient’sparticularpro-

blemsevermorevisible.Aspectacularreductioninthecostof

reading,orsequencing,thedna“bases”thatmakeuphumange-

neticinformationisaddinga newlevelofindividuality.Itisnow

possibletoinspectgeneticdifferenceswithaneasepreviouslyun-

imaginable,andthustoknowsomethingaboutpropensitiesto

diseasewellbeforeanysymptomsshowup.

Nobodyknowsexactlyhowmanyhumangenomeshavebeen

fullysequenced,anddifferentsequencingproceduresreadthege-

nometodifferentdegrees—therearequickskimsandpainstaking

philologicalstudies.Butthenumberisinthemillions(seechart

overleaf ).Bythe2030sgenomesequencingislikelytobeasrou-

tineinsomeplacesastakinga pin-prickofbloodfroma baby’s

heelistoday—itmayevenbepartofthesameprocedure.Genome

scienceisbecominga matterofpracticalmedicine.Newtherapies

thatmakeitpossibletoadjustoreditthisgeneticinheritanceare

comingtomarket.

Thisfloodofdataisallowingmedicinetobecomemoreprecise

andmorepersonal—inmanyways,thep-wordsaretwosidesof

thesamecoin.Previouslyrecognisedgeneticdiseases,suchas

Jansen’s,havebeentracedtospecificgenesandcanbeconnected

todefectsintheproteinstheycreate(almostallgenesdescribe

proteins,andproteinsdoalmostallthebody’schemicalwork).

Mostofthesediseasesarerare,inthattheytypicallyaffectnomore

Populationsofone

Medicine is getting to grips with the fact that everyone is an individual, says Natasha Loder

Personalised medicine

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