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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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