rev bras hematol hemoter. 2015;37(4):275–276
w w w . r b h h . o r g
Revista
Brasileira
de
Hematologia
e
Hemoterapia
Brazilian
Journal
of
Hematology
and
Hemotherapy
Letter
to
the
Editor
Klotho
gene
polymorphisms
and
their
association
with
sickle
cell
disease
phenotypes
DearEditor,
Wereadwithgreatinteresttherecentreviewpresentedbyde SouzaPachecoandGoncalves,1andwewouldliketobriefly
reportourexperiencewithKlotho(KL)singlenucleotide poly-morphisms(SNPs)andsicklecelldisease(SCD).
SCD presents a phenotypic heterogeneity that has not beenfullyelucidatedyet.Geneticmodifiersand environmen-tal effectsmay account forthe different clinical outcomes observed.SomegeneticmodulatorsofSCDarewellknown, however,theydonotexplainallthephenotypicvariations.2,3
Geneticassociationstudieshavetriedtoelucidatethis vari-abilitybyevaluatingSNPsingenesotherthanthebetaglobin
gene.However,thesedatastillneedtobevalidated.2–4
AssociationbetweenKLSNPsandclinicalmanifestations ofSCDhavebeenobserved,especiallyrelatedwithpriapism andlegulcers.5–9 Despitetheexistenceofsomedataabout
thistopic,theseassociationshavenotbeenconfirmed world-wide.Thus,weaimedtostudy KLSNPs in109steady state SCDpatients,74(68%)withSCA,10(9%)withHemoglobin(Hb) S/beta-thalassemia,and25(23%)withHbSC.Themeanage was32.6±11.3yearswithpredominanceoffemales(62.3%). Thepatientswere followedinthe OutpatientClinicsofthe Escola Paulista de Medicina, Universidade Federal de São Paulo(UNIFESP), Brazil.TheInstitutionalEthics Committee approvedthisstudyandinformedconsentwasobtained.We studiedthecorrelationbetweenthers211234andrs2249358 SNPs and priapism9; and between rs516306 and rs685417
and leg ulcers.8 The DNA was obtained from peripheral
bloodleukocytesusingastandardkit(QIAampDNAminikit, QIAGEN).Thers2249358andrs516306 SNPs wereidentified by polymerase chain reaction (PCR) followed by digestion withrestrictionenzymes (RFLP),asdescribed before.8,9 The
rs2111234and rs685417SNPs were identified bythe allele-specific oligonucleotide-PCR (ASO-PCR) method. Statistical analysiswasperformedusingGraphPadPrism® (SanDiego,
CA,USA);anddifferenceswithap-value<0.05were consid-eredstatisticallysignificant.
Ofthe41malepatientsinthisstudy,fourteen(34%)had ahistory ofpriapism,11 withSCA and3 withHb SC.The
medianageofthepatientswithpriapism wassignificantly higherthantheageoftheindividualswithoutthis manifes-tation[32.5years(range:25–68)and27.5years(range:20–56), respectively;p-value=0.03].
We did notfind any association between priapism and rs211234[p-value=0.4;OddsRatio(OR):2.20;95%confidence interval(95%CI):0.45–10.63]orrs2249358(p-value=0.72;OR: 1.50;95%CI:0.37–6.08).OurresultsweresimilartoElliotetal. who didnotconfirmanyassociationbetweenrs211234and priapism.6 However,theseresultswerediscordant withthe
dataofNolan,whodescribedasignificantassociationbetween priapismandtheseSNPs.9Thesmallnumberofpatients
stud-iedcouldhaveinfluencedtheseresults.
Thefrequencyoflegulcers(19%)wassignificantlymore frequentinmalesthanfemales(29.2%vs.13.2%respectively,
p-value=0.047). Regarding the genotype, 20 (95%) patients werediagnosedasSCAandone(5%)asHbSC.
ApreviousstudyaboutKLSNPsandlegulcersreportedan association.8 Nevertheless, wedidnotfind any association
betweenrs516306(p-value=0.29;OR:2.1995%CI:0.67–7.12) orrs685417(p-value=1.00;OR:0.95;95%CI:0.33–2.73)andleg ulcers.
AlthoughwedidnotconfirmanyrelationshipbetweenKL
SNPs and clinical manifestations, the importanceof these SNPs inSCD needstobebetterelucidated.Giventhe rele-vanceofthisgene,ashighlightedbydeSouzaPachecoand Goncalves,1webelievethatmoreresearchisneededtoclarify
thisassociation.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgements
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8.NolanVG,AdewoyeA,BaldwinC,WangL,MaQ,WyszynskiDF, etal.Sicklecelllegulcers:associationswithhaemolysisand SNPsinKlotho,TEKandgenesoftheTGF-beta/BMPpathway. BrJHaematol.2006;133(5):570–8.
9.NolanVG,BaldwinC,MaQ,WyszynskiDF,AmiraultY,Farrell JJ,etal.Associationofsinglenucleotidepolymorphismsin klothowithpriapisminsicklecellanaemia.BrJHaematol. 2005;128(2):266–72.
ClaudiaR.LustosaSouza,MarilyM.AzevedoShimmoto, PerlaVicari,GrazielleMecabo,MarthaMarianaArruda, MariaStellaFigueiredo∗
UniversidadeFederaldeSãoPaulo(UNIFESP),SãoPaulo,SP,Brazil
∗Correspondingauthorat:RuaDr.DiogodeFaria,824,3◦andar,
CEP:04037-002,VilaClementino,SãoPaulo,SP,Brazil. E-mailaddress:[email protected](M.S.Figueiredo).
Received20January2015 Accepted4February2015 Availableonline4May2015
1516-8484/©2015Associac¸ãoBrasileiradeHematologia, HemoterapiaeTerapiaCelular.PublishedbyElsevierEditora Ltda.Allrightsreserved.
