True_Love 2019-10-01

WHENTOGO

FORTESTING

Askyourhealthprofessional

aboutgenetestingif:

Youhavea provenfamilyhistory

ofbreastorovariancancers.

“About5-10%ofcasesofbreast

and10-20%ofovariancancers

areassociatedwithmutationsin

eitherBRCA1orBRCA2genes,”

Kinnearsays.

Youhavea familyhistoryof

X-linkeddiseases.Theserange

fromAddison’sandalbinism

tohaemophiliaandmuscular

dystrophy.

“Youhavea raredisorderand

havebeenona diagnostic

odysseywithoutdefinitive

diagnosis”,asKinnearputsit.

Testingmayprovideananswer.

Thebenefitsofgenetictesting

formedicalconditionsarethat

forsinglegenedisorders,testing

candetectdiseasebeforethe

onsetofsymptoms.“Armedwith

thisknowledge,you’reable,with

thehelpofgeneticcounsellors

andphysicians,tomake

informedmedicalandlifestyle

decisions,”Kinnearadds.The

outcomescanbelife-changing,

sopre-andpost-testgenetic

counsellingiscritical.And

remember:notestisa guarantee

thatyou’llbehealthyforever.

“Weworryonlyifa woman

hasalreadyhadcancerinone

breastbeforeage35,orhastwo

immediaterelativeswhohadit

beforemenopauseorwhohad

ovariancancerbeforetheage

of30,”saysProfessorJustus

Apffelstaedt,headoftheBreast

ClinicatTygerbergHospital.

told CNBC business news recently that

there are now more than 75 000 genetic

tests, with more than 10 new tests enter-

ing the market every day. Some are for

specific disease diagnoses, but most now

focus on wellness and fitness, offered at

genetic testing labs that are springing

up all over. Many offer testing online,

delivering cheek-swab kits in the mail.

According to Global Market Insights, the

genetic testing market is set to exceed

$22 billion (R335 billion) in five years.

BLINDED BY SCIENCE?

But as genetic testing grows, so does

controversy around it. “There are com-

panies offering genetic tests that aren’t

necessarily based on solid empirical

evidence,” Associate Professor in the

Department of Biomedical Sciences at

Stellenbosch University, Craig Kinnear,

says. “There’s been an explosion of direct-

to-consumer genetic testing companies

that promise clients diet plans and fitness

regimes based on their genetic make-up.

The problem is that you can send your

sample to different companies and get

different answers.”

Two years ago, American medical

journalist, Rebecca Robbins, experienced

this when she took two mail-order genetic

tests that contradicted each other. They

delivered “different interpretations of

what certain regions of my genome

meant for my risk for tendon injuries,

for instance, or my propensity for high

blood pressure”, she wrote on health

news website, http://www.statnews.com. She

added that the advice she was given “was

either general – like stretch well before

exercise – or oddly specific, like the menu

I was given telling me to eat quinoa on

Sundays”. Genetic tests had promised

to help her achieve peak fitness.

The problem, Kinnear says, is that

while there are strong genetic under-

pinnings for conditions such as breast

and ovarian cancer, cystic fibrosis or

muscular dystrophy (since inheriting

these single gene mutations will result in

you developing the disease), for complex

traits such as obesity and fitness levels,

very little is encoded by a single gene.

“These complex traits are a result of the

interaction between multiple genes and

the environment (which includes behav-

iour like smoking and drinking alcohol).

We still don’t know enough about human

genesandtheirinteractionwithone

anotherandtheenvironmenttobeable

togiveaccurateadviceonthebestdiet

tofollow,orwhichexerciseprogramme

isbest-suitedtoanindividual,”Kinnear

explains.Infact,hesays,studieshave

shownthatgeneticsplayonlya small

rolewhenitcomestotheeffectsofdiet

andexercise,andbehaviourmatters

muchmore.“Acontrolledtrialpublished

intheJournaloftheAmericanMedical

Associationfoundnodifferenceinweight

lossbetweengroupsofpeoplewhowere

matchedtoeithera high-fatora low-fat

dietbasedontheirgeneticmake-up.

Similarly,anindependentinvestiga-

tionof 38 genesfrequentlyincludedin

nutrigenomictests(testslookingatthe

relationshipbetweengenes,nutrition

andheath)providedbyseveralprivate

genetictestingcompaniesfoundnoas-

sociationwithdietaryintakeandanyof

thesegenes,”hesays.

What’smore,differentgene-testing

companiesusedifferenttests,genes

andscientificliteraturetoreachtheir

conclusions,Kinnearcontinues.“Sothe

resultsofdirect-to-consumergenetic

tests,inparticularthoseteststhattell

youexactlywhichexercisestodoand

whattoeat,shouldbetakenwitha grain

ofsalt,”headds.

THEBOTTOMLINE

GeneWatchUK,a not-for-profitgroup

thatmonitorsdevelopmentsingenetic

technologies,reportsthatformorethan

15 yearsithasexposedcompaniesmak-

ingmisleadingclaimsabouttestresults.

“Genetictestsarenotcurrentlyregulated,”

itnotes.“Thismeanspeoplecouldeasily

bemisledabouttheirhealth.Without

properregulation,genetictestingcould

beusedtoexpandthedrugmarketto

healthypeopleidentifiedasathighgenetic

risk;peoplewouldreceiveunnecessary

medication;andtheunderlyingcauseof

heartdisease,cancerandobesitycould

beignored,withseriousimplications

forfuturehealth.”Thegroupconcludes

thatformostpeople,eatinga balanced

diet,gettingenoughexerciseandnot

smokingaremuchmoreimportantin

determiningyourhealththanyourgenes

are.Talktoyourdoctorfordietadvice

orvisit:www.adsa.org.za/Portals/14/

Documents/FoodBasedDietaryGuide-

linesforSouthAfrica.pdf.

HEALTH

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