J. Pediatr. (Rio J.) vol.93 número6

www.jped.com.br

ORIGINAL

ARTICLE

Determining

the

frequency

of

morphological

characteristics

in

a

sample

of

Brazilian

children

夽

,

夽夽

Eduardo

Perrone

,

Thais

Arbocese

Zanolla

,

Rodrigo

Ambrosio

Fock

,

Ana

Beatriz

Alvarez

Perez

_,

_Decio

_Brunoni

a_{UniversidadeFederaldeSãoPaulo(UNIFESP),DepartamentodeMorfologiaeGenética,SãoPaulo,SP,Brazil}

b_{UniversidadePresbiterianaMackenzie,CentrodeCiênciasBiológicasedaSaúde,ProgramadePós-Graduac¸ãoemDistúrbiosdo}

Desenvolvimento,SãoPaulo,SP,Brazil

Received13August2016;accepted20December2016 Availableonline27July2017

KEYWORDS

Anomalies; Morphological; Frequency; Brazilian; Children

Abstract

Objective: Toestablishthefrequency of82 morphologicalfeatures inasampleofBrazilian children(between3and13yearsold),tounderstandtheinfluenceofage,gender,andethnicity. Methods: Thiswasacross-sectionalstudythatevaluated239childrenwithtypicaldevelopment (between3and13yearsold)regardingthepresence of82 morphologicalcharacteristics. A previouslydescribedprotocol,basedontheLondonDysmorphologyDatabase,wasappliedto evaluatethesample.ThisprotocolwasculturallyadaptedtoBrazilianPortuguese.

Results: Thefrequencyof82morphologicalcharacteristicswasestablishedinthesample;of 82 characteristics, 50%were considered morphological anomalies(frequency lessthan4%). Atleast25%ofthesamplepresentedmore thanoneminormorphologicalanomaly.Agewas showntoinfluencethefrequencyofthefollowingmorphologicalcharacteristics:widow’speak, prominentantihelix,prominentupperlip,irregularorcrowdedteeth,andclinodactyly,buthad noinfluenceonthefrequencyofminormorphologicalanomalies.Genderinfluenceddysplastic earsand attachedearlobe, but hadno influence onthe frequency ofminor morphological anomalies;ethnicityshowedinfluenceoncamptodactylyandprominentantihelix.Astatistically significantdivergencewasobservedregarding43ofthe73morphologicalcharacteristicsthat couldbecomparedwithliteraturedata(58.9%).

夽

Pleasecitethisarticleas:PerroneE,ZanollaTA,FockRA,PerezAB,BrunoniD.Determiningthefrequencyofmorphologicalcharacteristics inasampleofBrazilianchildren.JPediatr(RioJ).2017;93:592---600.

夽夽

StudycarriedoutatUniversidadeFederaldeSãoPaulo(UNIFESP),SãoPaulo,SP,Brazil. ∗_{Correspondingauthor.}

E-mails:[email protected],[email protected](E.Perrone).

http://dx.doi.org/10.1016/j.jped.2016.12.010

Conclusions: Thestudy determinedthefrequencyof82morphological characteristicsin239 children withtypicaldevelopment.Agewasthevariablethatshowedmoreinfluenceonthe frequencyofmorphologicalcharacteristics,andcomparisonwithliteraturedatashowedthat thefrequencydependsonvariablessuchasageandethnicity.

©2017SociedadeBrasileiradePediatria.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

PALAVRAS-CHAVE

Anomalias; Morfológicas; Frequência; Brasileiras; Crianc¸as

Determinac¸ãodefrequênciadecaracterísticasmorfológicasemumaamostra decrianc¸asbrasileiras

Resumo

Objetivo: Estabelecer afrequência de 82 características morfológicas em uma amostrade crianc¸asbrasileiras(entre3e13anos),paraentenderainfluênciadaidade,sexoeetnia. Métodos: Estefoiumestudotransversal.Avaliamos239crianc¸ascomdesenvolvimentotípico (entre3e13anos),emrelac¸ãoàpresenc¸ade82característicasmorfológicas.Aplicamosum protocolodescritoanteriormente,baseadonoLondonDysmorphologyDatabase,paraavaliar nossaamostra.EsteprotocolofoiculturalmenteadaptadoaoportuguêsdoBrasil.

Resultados: Afrequênciade82característicasmorfológicasfoiestabelecidaemnossaamostra; de82 características,50%foramconsideradasanomaliasmorfológicas(frequênciainferiora 4%).Pelomenos25%danossaamostraapresentoumaisdeumaanomaliamorfológicamenor. Aidademostrouinfluêncianafrequênciadasseguintescaracterísticasmorfológicas:‘‘bicode viúva’’, ‘‘anti-héliceproeminente’’,‘‘lábio superior proeminente’’,‘‘dentes irregulares ou encavalados’’e‘‘clinodactilia’’,masnãoteveinfluêncianafrequênciadeanomalias morfológ-icasmenores.Osexomostrouinfluêncianasseguintescaracterísticas:‘‘orelhasdisplásicas’’e ‘‘lóbulodaorelhaaderente’’,masnãoteveinfluêncianafrequênciadeanomalias morfológ-icasmenores;aetniamostrouinfluênciana‘‘camptodactilia’’e‘‘anti-héliceproeminente’’. Houvedivergência(estatisticamentesignificativa)em43característicasmorfológicasde73que pudemoscompararcomosdadosdaliteratura(58,9%).

Conclusões: Estabelecemosafrequênciade 82característicasmorfológicas em 239crianc¸as comdesenvolvimentotípico.Aidadefoiavariávelquemostroumaiorinfluênciana frequên-ciade características morfológicase acomparac¸ãocomdadosda literaturamostrouque a frequênciadependedevariáveiscomoidadeeetnia.

©2017SociedadeBrasileiradePediatria.PublicadoporElsevierEditoraLtda.Este ´eumartigo OpenAccesssobumalicenc¸aCCBY-NC-ND(http://creativecommons.org/licenses/by-nc-nd/4. 0/).

Introduction

Amorphologicalanomalyisaphenotypethatissubstantially differentfromthatobservedinareferencepopulation.1_This differencecanbedefinedastheoccurrenceofthe pheno-typic characteristic in less than 2.5% of the population.1 Some authorsconsiderastatistical thresholdof 4%for its definition.2_{Morphologicalanomaliesareclassifiedasmajor,} when their presence results in medical consequences for the individual, and as minor, when they do not generate sucheffects.2_{Thepresenceofminormorphological} anoma-liesisconsideredanindicatorofanabnormalembryological developmentprocess;therefore,studieshavealready indi-catedacorrelationbetweenminormorphologicalandmajor anomalies.2---4

Most studies on the frequency of morphological char-acteristics assessed newborns,2---5 _{and it is known that} morphological characteristics may change according to age.6---11

Themostrecentsurveyonthefrequencyof morphologi-calcharacteristicswascarriedoutbyMerksetal.inasample ofDutchchildrenagedbetween8and14years.12

There are no data on the frequency of morphological characteristics in a sample of Brazilian children. Addi-tionally,the definition of a minormorphological anomaly involves a statistical concept. Based on these assump-tions, this study aimed to determine the frequency of 82 morphological characteristics in a sample of children with typical development and to verify the influence of the variables age, gender, and ethnicity on their frequency.

Methods

Sampleselection

history,characterizedbytheabsenceofneuropsychomotor developmentaldelayand/orpsychiatricdisorders.

Statisticalconsiderations

Considering a 95% confidence level and a 5% confidence interval,andbasedonpreviousliteraturedataonthe fre-quencyofminoranomalies in thepopulation,2---4 _{a sample} of200childrenwasestimated.Tocompensateforpossible losses,thestudyincluded239children.

Categoricalvariablesweredescribedasfrequencies.To comparethefrequenciesofthemorphological characteris-tics withthosealready described, the Z-test wasused to comparebetweentwoproportions.

To determine whether the frequency of each anomaly showed a statistically significant difference according to gender,age,andethnicity,thechi-squaredtest orFisher’s exact test was used.The results withp≤0.05 were con-sideredsignificant.Statisticalanalysiswascarriedoutusing theSPSSsoftwareforstatisticalanalysis(IBMCorp.Released 2011, IBM SPSS Statistics for Windows, Version 20.0, NY, USA).

Protocoluseandmorphologicalevaluationofthe children

Childrenwere evaluatedaccording toa protocol contain-ing82morphologicalcharacteristicsbasedonthedefinition oftheLondonDysmorphologyDatabase(LDDB),whichlists approximately2000 characteristics. The protocol used to evaluate the 82 characteristics has been previously used byMiles etal.toevaluate children withautismspectrum disorder(ASD).13_{Thisprotocolisbeingvalidatedforusein} childrenwithASDinBrazil,andpartofthisprocessdepends on its application in children with typical development. Thus,theauthorschosetoapplythisprotocoltothepresent sample.

Thedefinitionofsomemorphologicalcharacteristicswas changedinrelation tothepreviousdefinitiongivenbythe LDDB,afteraconsensusamongfourgeneticists(authorsof thestudy),aimingtomakethemmoreobjective.The char-acteristicswiththedescriptionaftertheculturaladaptation areshowninTable1.

For anthropometric data collection, a vertical anthro-pometer and a metric tape were used. During the morphologicalexamination,thefollowingweremeasuredin additiontoheight;ears,hands,middlefingers,andmiddle toes. The curves used to define micro/macrotia; elon-gated/smallfeet;large/small hands;and elongated/short phalangesarethosefoundinSmith’sRecognizablePatterns ofHumanMalformation,14 _{usingthe±2SD(standard} devia-tions)limit.Aheight-for-agemeasurementbelowthethird percentilein theWHOcurvewasdefinedasshortstature. Theothercharacteristicswerescoredasabsentorpresent. The 239children wereevaluatedby thefirstauthorof thisstudy,whoisalsoageneticist,intwomunicipalschools in the city of Barueri (state of São Paulo, Brazil). It was decidedtoevaluatechildrenfromthepublicschoolsystem topreventtheethnicselectionbiasthatmayoccurinprivate schools.

Regulatoryaspects

ThisstudywassubmittedtoandapprovedbytheResearch EthicsCommitteeofUNIFESP.Childrenwereevaluatedafter parentsortutorsgavetheirauthorizationbysigningthefree andinformedconsentform.

Results

Overallsamplecharacteristics

Atotalof239childrenaged3to13yearswereevaluatedin municipalschoolsofthecityofBarueri(SP).

Themeanageofthesamplewas7yearsand9months±2 years and 10 months, with a median of 7 years and 6 months.Thesamplecomprised111malesubjects(46.4%). Regarding ethnicity, the distribution of the analyzed sub-jectsconsistedof 62.3%white(n=149),25.9%mixed-race (n=62),10.9%Africandescendants(n=26),and0.8%native Brazilians(n=2).

Determinationofthefrequencyofmorphological characteristics

Table1showsthefrequenciesofeachassessed morpholog-icalcharacteristic.

Of the 82 morphological characteristics evaluated, 41(50%)showedafrequency<4%,andcouldbeconsidered asmorphologicalanomalies.Therefore,oneminoranomaly wasobserved in42 subjects (17.5%),twoanomalies in 12 subjects (5%),and threeanomalies in sixsubjects (2.5%). Therefore,60children(25%)hadatleastoneminoranomaly.

Determinationofthefrequencyofmorphological characteristicsbygender

Of the 82 evaluated characteristics, only two showed frequencies with significant differences when divided by gender:dysplasticears(20.7%[13.6---28.2%]in111male sub-jectsvs.7%[2.58---11.4%]in128femalesubjects;p=0.002) and attached earlobe (10.8% [5.03---16.57%] in 111 male subjects vs. 21.2% [14.1---28.28%] in 128 female subjects; p=0.032.

Determinationofthefrequencyofmorphological characteristicsbyagegroup

The239studysubjectsweregroupedintofivegroupswith differentageranges: groupI,from3to5years;GroupII, from5yearsand1monthto7years;GroupIII,from7years and1monthto9years;GroupIV,from9yearsand1month to11years;andgroupV,from11yearsand1monthto13 years.

Fivecharacteristics showedsignificant frequency varia-tionsdependingonage:widow’speak,prominentantihelix, prominentupperlip,crowdedteeth,andclinodactyly.

Table1 Frequencyofmorphologicalcharacteristicsfound.

Morphologicalcharacteristic Frequency(%) 95%CI n

Shortstaturea _{0.8 −0.33---1.93 239}

Unusualhairwhorl/pattern 20 14.65---25.35 215

Widow’speak 5.9 2.91---8.89 239

Frontalupsweep/cowlicka _{1.3 −0.14---2.74 239}

Asymmetricears 5 2.24---7.76 239

Dysplasticears 13.4 9.08---17.72 239

Largeears(macrotia)a _{0.4 −0.4---1.2 239}

Low-setearsa _{0.8 −0.33---1.93 239}

Posteriorlyrotatedearsa _{0.8 −0.33---1.93 239}

Earpitsa _{0 DNA 239}

Prominentears 9.6 5.87---13.33 239

Simpleears 9.2 5.54---12.86 239

Smallears/microtiaa _{1.7 0.06---3.34 239}

Prominentantihelix 33.9 27.9---39.9 239

Notchedearhelix 8.4 4.8---11.92 239

Crumpledearhelixa _{0 DNA 239}

Over-foldedearhelix 5.4 2.53---8.27 239

Pitsofearhelixa _{0 DNA 239}

Prominentearhelix 9.6 5.87---13.33 239

Attachedearlobe 16.3 11.62---20.98 239

Large/widenose 15.1 10.56---19.64 239

Short/smallnosea _{0.4 −0.4---1.2 239}

Asymmetricfacea _{0.8 −0.33---1.93 239}

Coarsefacialfeaturesa _{0 DNA 239}

Flatfacea _{1.3 −0.14---2.74 239}

Mid-facehypoplasiaa _{1.3 −0.14---2.74 239}

Smallfacea _{2.1 0.28---3.92 239}

Long/narrowface 5 2.24---7.76 239

Triangularface 4.2 1.66---6.74 239

Dimpledorgroovedchin 3.8 1.38---6.22 239

Pointedchina _{1.3 −0.14---2.74 239}

Flatzygomaticregiona _{1.3 −0.14---2.74 239}

Prominentmandible/prognathism 2.9 0.77---5.03 239

Smallmandible/micrognathia 2.5 0.52---4.48 239

Longphiltrum 12.1 8.0---16.3 239

Prominent/deepphiltrum 9.2 5.54---12.86 239

Shortphiltrum 8.4 4.88---11.92 239

Simple/absent/flatphiltruma _{2.1 0.28---3.92 239}

Widephiltrum 2.9 0.77---5.03 239

Down-turnedcornersa _{0.8 −0.33---1.93 239}

Cupidbowshapeofmoutha _{1.7 0.06---3.34 239}

Macrostomiaa _{0.8 −0.33---1.93 239}

Microstomia 2.5 0.52---4.48 239

Open-mouthappearancea _{0.4 −0.4---1.2 239}

Everted/prominentlowerlipa _{0.8 −0.33---1.93 239}

Thicklowerlip 8.8 5.21---12.9 239

Cleftupperlip(nonmidline)a,b _{0 DNA 239}

Prominentupperlip 7.5 1.38---6.22 239

Thinupperlip 3.8 1.38---6.22 239

Enamelabnormalitiesa _{0.8 −0.33---1.93 239}

Crowdedorirregularteeth 12.6 8.39---16.81 239

Abnormaltoothshapea _{2.1 0.28---3.92 239}

Smallteetha _{0 DNA 239}

Widelyspacedteeth 4.6 1.94---7.26 239

Largehandsa _{0.8 −0.33---1.93 239}

Smallhands 3.8 1.38---6.22 239

Camptodactylya _{1.3 −0.14---2.74 239}

Table1 (Continued)

Morphologicalcharacteristic Frequency(%) 95%CI n

Cutaneoussyndactylyofthefingersa _{0.4 −0.4---1.2 239}

Taperingfingers 3.8 1.38---6.22 239

Thinfingers 7.5 1.38---6.22 239

Hypoplastic/shortmetacarpalsa _{0 DNA 239}

Shortphalangesa _{1.7 0.06---3.34 239}

Widephalangesa _{0.4 −0.4---1.2 239}

Longphalangesa _{1.7 0.06---3.34 239}

Broadthumbs 7.5 1.38---6.22 239

Dystrophic(dysplastic),includingstriatednailsa _{0.4 −0.41---1.21 235}

Hyperconvex 8 4.55---11.45 238

Hypoplastic/smallnails 2.9 0.77---5.03 238

Shortnails 10.5 6.61---14.39 238

Clubfootvarusa _{0 DNA 239}

Largefeeta _{2.1 0.28---3.92 239}

Smallfeeta _{0.8 −0.33---1.93 239}

Widefeet 10.9 6.9---14.85 239

Halluxvalgus 10 6.2---13.8 239

Broadtoes 3.3 1.04---5.56 239

Overlappingtoes(includingclinodactyly) 65.7 59.68---71.72 239

Shorttoes 2.5 0.52---4.48 239

Syndactylyof2---3toesa _{0.4 −0.4---1.2 239}

Syndactylyoftoes(exceptfor2---3toes)a _{0.8 −0.33---1.93 239}

Wide-spacedtoes 9.2 5.54---12.86 239

Camptodactyly/hammertoesa _{0.4 −0.4---1.2 239}

a_{Characteristicconsideredasamorphologicalanomaly(consideringthe4%threshold).} b _{Characteristicconsideredasamajormorphologicalanomaly.}

DNA,doesnotapply.

comparinggroupsIvs.II;IIvs.III;IIIvs.IV(14.8%vs.31.7% vs.57.5%vs.34.2%; p<0.05inall comparisons);thethird, whencomparinggroups II xIII (11.1%vs. 0.0%;p=0.041); thefourth,whencomparinggroupsIIvs.III(4.2%vs.17.5%; p=0.044); and the fifth, when comparing groups I vs. II (29.6%vs.12.7%;p=0.024).

Agedid notinfluencethe frequency ofindividuals who hadatleastoneminormorphologicalanomaly.GroupIhad 22.2%ofsubjectswithatleastoneminoranomaly;groupII, 19.6%;groupIII,30.7%;groupIV,32.4%;andgroupV,36.3% (p=0.451).

Determinationofthefrequencyofmorphological characteristicsbyethnicity

The proportion of individuals with at least one morpho-logical anomaly did not present a statistically significant differencebetween the ethnic groups; 23.9%, 30.7%, and 34.4% of white, African-descendants, and mixed-race individuals, respectively, presented at least one minor morphologicalanomaly(p=0.407).Theonlycharacteristics that showed variations according to the ethnicity were: prominent antihelix (30.2% vs. 23.0% vs. 48.3% vs. 0% in white, African descendants, mixed-race, and native Brazilians, respectively; p=0.026), and ‘‘camptodactyly’’ (0%vs.7.7%vs.1.6%vs.0%inwhite,Africandescendants, mixed-race,andnativeBrazilians,respectively;p=0.025).

Discussion

Ingeneral,a frequencyofat least25% ofindividualswith at least one morphological anomaly was observed in the presentsample.Thefrequenciesofthemorphological char-acteristics,whencomparedwiththosealreadydescribedin theliterature,showeddiscrepancies.Whenstratifying chil-dren by age, ethnicity,and gender, thevariables age and ethnicityappearedtoinfluencethefrequencyof character-istics.

Frequencyofidentifiedmorphological characteristics

Considering the 4% threshold to define a morphological anomaly, only 41 of theassessed characteristics could be considered assuch.Most ofthese characteristics (39)are minor morphological anomalies, except upper lip cleft non-midline and short stature, which may have clinical implications and association with malformations and skeletal dysplasias, respectively, being considered major morphologicalanomalies.12

Inthepresentstudy,25%ofthesamplehadatleastone minoranomaly.

Table2 Morphological characteristicsfound withsignificant statisticaldifference incomparisonswith thestudy by Merks etal.12

Morphologicalcharacteristic Observedfrequency(%) (Perrone,2016)

Observedfrequency(%) (Merksetal.,2006)12

Z-value p-value

Unusualhairwhorl/pattern 20 0.1 −13.6 <0.001

Frontalupsweep/cowlick 1.3 15.8 6.0 <0.001

Asymmetricears 5.0 1.7 −2.95 0.003

Dysplasticears 13.4 0.0 −11.2 <0.001

Prominentears 9.6 2.6 −4.9 <0.001

Simpleears 9.2 0.1 −8.9 <0.001

Notchedearhelix 8.4 0.0 −8.8 <0.001

Prominentearhelix 9.6 2.6 −4.9 <0.001

Large/widenose 15.1 0.4 −11 <0.001

Short/smallnose 0.4 9.3 4.65 <0.001

Hypoplasiaofthemiddlethirdoftheface 1.3 0 −3.42 <0.001

Long/narrowface 5.0 2.2 −2.43 0.01

Triangularface 4.2 0.1 −5.79 <0.001

Prominentmandible/prognathism 2.9 0.3 −3.88 <0.001

Longphiltrum 12.1 3.1 −5.68 <0.001

Prominent/deepphiltrum 9.2 1.8 −5.63 <0.001

Shortphiltrum 8.4 2.8 −3.92 <0.001

Simple/absent/flatphiltrum 2.1 5.3 2.1 0.03

Down-turnedcorners 0.8 0.1 −1.97 0.047

Open-mouthappearance 0.4 0.0 −1.96 0.04

Thicklowerlip 8.8 14.5 2.32 0.02

Prominentupperlip 7.5 2.1 −4.29 <0.001

Thinupperlip 3.8 8.9 2.66 0.007

Enamelabnormalities 0.8 0 −2.78 0.005

Irregularorcrowdedteeth 12.6 0 −10.9 <0.001

Abnormaltoothshape 2.1 0.1 −3.8 <0.001

Widelyspacedteeth 4.6 0 −6.54 <0.001

Largehands 0.8 0 −2.78 0.005

Smallhands 3.8 0 −5.9 <0.001

Camptodactyly 1.3 0 −3.4 0.006

Clinodactyly 16.7 3.6 −12.6 <0.001

Taperingfingers 3.8 0.4 −4.36 <0.001

Broadthumbs 7.5 0.9 6.2 <0.001

Hyperconvex 8.0 0 −8.65 <0.001

Hypoplastic/smallnails 2.9 0.2 −4.2 <0.001

Shortnails 10.5 0.9 −7.9 <0.001

Largefeet 10.9 0.3 −9.3 <0.001

Halluxvalgus 10.0 2.4 −5.4 <0.001

Broadtoes 3.3 0.7 −3.4 <0.001

Overlappingtoes(includingclinodactyly) 65.7 0.3 −26.7 <0.001

Shorttoes 2.5 0.2 −3.8 <0.001

Syndactylyoftoes(except2---3toes) 0.8 0 −2.78 0.005

Wide-spacedtoes 9.2 26.3 5.59 <0.001

morphological anomaly; Mèhes et al.,3 _{a prevalence} of 16.3%; Leppig et al.,4 _{a prevalence of 39.9%; and} Tsai et al.,5 _{a prevalence of 43.3% in Chinese new} borns.

Thedifferenceinfrequenciesfoundbetweenthestudies canbejustifiedbythenumberofcharacteristicsassessed, the evaluation method,and the ethnicityof the assessed children.

The41characteristicsthatwerenotconsideredas mor-phologicalanomalies---astheywereobservedinover4%of

thepresentsample---aremorphologicalvariantsornormal characteristics(frequency>50%).3,4

Influenceofthevariablesage,gender,and ethnicityontheobservedcharacteristics

morphologicalanomaliesoftheassessednewborns.Leppig etal.4_{alsodidnotconsiderthisissue;however,theystated} thatprominent heel, for instance, was an anomaly found onlyingirls.

IncontrastwithLeppigetal.4 _{andMardenetal.,}2 _Tsai etal.5_{emphasizedthatvariablessuchasgender,maternal} age, and gestationalage did not influence the frequency ofanomalies foundin theirsample. The influenceof gen-der onmorphological variants wasnot assessed in any of them.

The present study demonstrated that, of the 82 mor-phological characteristics assessed, only two showed a statisticallysignificantdifferencewhenconsideringgender: dysplastic ears and attached earlobe. These two char-acteristics, due to their frequency, would be considered morphologicalvariants.Forallothermorphologicalvariants andmorphological anomalies, no influence of gender was observedontheidentifiedfrequencies.

In short, gender is a variablethat does not appear to influencethemorphologicalcharacteristicsconsidered mor-phologicalanomalies.

Regardingtheinfluenceoftheagerangeonthefrequency oftheassessedcharacteristics,itisknownthatgenetic syn-dromephenotypes,aswellastheindividuals’morphological characteristics,changeovertime6---11_{;however,noneofthe} aforementioned studies allowed the determinationof the agegroup interferenceonthe frequencyof theidentified morphologicalcharacteristics.

The present study was a pioneer in evaluating the influence of this variable.All characteristics that showed statisticallysignificantvariationsinfrequencyaccordingto agewere morphological variants.The characteristics that showedany variation in theirfrequency according toage were:widow’speak,prominentantihelix,prominentupper lip,crowdedteeth,andclinodactyly.

The onsetof the characteristic crowded teeth after 7 yearsofageisperhapsduetotheagegroup,whendeciduous teethstarttobereplacedbypermanentdentition.

Thecharacteristicswidow’speakandprominentantihelix presentedincreased frequencywithage. This mayreflect thefact thatsome characteristics,even thoughtheymay bepresent from birth,are easier toidentifyin older age groups.Incontrast,clinodactylyismoreeasilyperceivedin youngeragegroups.

Merks etal.,12 _{when comparingthe frequencyof} char-acteristicsfound intheirstudy onschoolchildren withthe frequencyidentifiedinprevious studiesonnewborns, also concludedthat thereis an important influence of age on theindividual’sphenotype.

Thesefindingsshowthatstudiesonthefrequencyof mor-phologicalcharacteristicswithlargersamplesinspecificage groups areimportanttodetermine whatis orwhat isnot considered a morphological anomaly for that specific age group.

All characteristics that varied according to age range werepreviously consideredasmorphologicalvariants.Age didnotinfluencethefrequencies observedforminor mor-phologicalanomalies.

Ethnicaspectsarenoteworthy,sincethemorphological characteristicsofskincolorandfacialfeaturesareusedto categorizewhattheliteraturecallsethnicityandcurrently, throughgenomicstudies,asancestry.

Demographic statisticsuse the self-declared skin color asan indicatorof ancestry. Thus, according todata from theBrazilianInstituteofGeographyandStatistics(Instituto BrasileirodeGeografiaeEstatística[IBGE],2010census),15 the Brazilianpopulation consistsof 47.7% ofwhite; 43.1% of mixed-race;7.6% ofAfricandescendants; 1.1%ofAsian descendants; and0.4%of nativeBrazilian individuals.The useofthechi-squaredtestofadherenceindicatedthatthere was adifference between the distributionof the present sampleregardingethnicityinrelationtotheBrazilian pop-ulation(p<0.001).

Suchdifferenceispredictable,sinceinthepresentstudy ethnicdesignationwasderivedfromobservationand phys-icalexamination,whereasthatofIBGEisself-reported.In turn,themiscegenationoftheBrazilianpopulationis con-sideredoneofthewidestintheworld,andinformationon themorphologicalphenotype,eitherdeterminedby physi-calcharacteristicsorself-declared,isnotagoodpredictor ofgenomicancestry.16,17

The absence of a statistically significant difference between the proportionof individuals with morphological anomalies,whenconsideringethnicity,wasexpected,since morphologicalanomaliesrepresentintrinsicdevelopmental alterationsandtherewouldbenoreasonfor themto pre-dominatein aparticular ethnicity.The factthat onlytwo ofthe82morphologicalfeaturesshowedsignificant differ-ences whenstratified by ethnicitycan bejustifiedby the evaluator’s ethnicconsiderationswhendefining character-istics(e.g.,thicklowerlip).

ComparisonwiththestudybyMerksetal.12

Dataon thefrequency of morphological characteristics in children’ssamplesarescarceintheliterature.

Inthissense,thepresentdataarebettercomparedwith thosebyMerksetal.12 _{Theauthorswerepioneersin} deter-miningthefrequencyofmorphologicalcharacteristics ina sample of the Dutch population witha median age of 11 years. Based on the data obtained in the assessment of 683characteristics(usingLDDB)in923children,frequencies wereestablished,allowingtheclassificationofthe charac-teristicsasmorphologicalanomaliesorvariants.

Ofthe73morphologicalcharacteristicsthatwere evalu-atedinbothstudiesandhadafrequencyotherthanzero,in 43(59%)astatisticallysignificant differencewasobserved between the frequencies found in the present study and thoseinthestudybyMerksetal.12_{Thecharacteristics} show-inganydiscrepancyareshowninTable2.

Some hypotheses can beraised toclarify this discrep-ancy:theethniccompositionofMerks’samplewasdifferent fromthatofthepresentsample(thefirstone,consistingof whitechildren, andthesecond oneconsistingofBrazilian children,theresultofmiscegenation);theagerangeofthe evaluatedpatientswasalsodifferent;thesubjectivityand thecontinuityofsomemorphologicalcharacteristicsmakes theirassessmentobserver-dependent.

Someexampleswillbeusedtoillustratethepreviously mentionedhypotheses.

Merks’12_{sample(8.8%vs.14.5%,respectively).However,as} theethnicalcriterionwasconsideredinthedefinitionofa thicklowerlip,andasthischaracteristicissubjectiveand continuous,inthesampleonlychildrenwhohadaverythick lowerlipwereconsideredaspresentingthischaracteristic, leadingtoits.

Tsai et al.,5 _{after assessing 3345 Chinese newborns,} verifiedthatethnicityinfluencedthefrequencyof morpho-logical features (single palmar crease, ascending oblique palpebral fissure, andfrontal bossingwere observed at a frequencyhigherthan4%inasampleofChinesenewborns, beingmorphologicalvariantsinthatsample).

The fact that some characteristics are continuous and subjectivemakesitdifficulttodefinethelimittoconsider them asnormal or altered,whichmayresult inunder-or overestimationoftheirfrequencies.

This reasoningappliestoclinodactyly,whose definition onlystatesa‘‘significantlateralbending,usuallyobserved inthefifthfinger’’.Thischaracteristicwasfoundin16.7% of the assessed individuals, in contrast to 3.6% in the Merksetal.12 _{sample. Probably,thelatter authors} consid-eredhigherdegreesofclinodactylyduringtheirevaluation. If the definition were clearer regarding the degree of acceptable bending,a similarfrequency might have been observed.

Anotherassessedcharacteristicthatshowedhigh preva-lenceintheevaluatedsample(65.7%)andcouldtherefore be considered as a normal variant was overlapping toes (includingclinodactyly). What ledto thishigh prevalence wastheinclusionofthetermclinodactylyinthedefinition, sinceclinodactylyof thefifthtoeinchildrenis acommon findingandhassubjectiveevaluation.

ThemedianageoftheMerksetal.12_samplewas differ-ent from the present sample (11 years vs. 7 years and 6 months,respectively). Theage groupof thepatients may haveinfluencedthedifferenceinsomefindings.When the present samplewasdividedintodifferentagegroups, the influenceoftheagevariablewasobserved.

Of the 43 characteristics that presented frequency discrepancy between the studies, 31 (72.1%) could be considered as morphological variants, one (2.4%) as a normal characteristic, and 11 (25.5%) as morphological anomalies. Of the 30 characteristics that showed sim-ilar frequencies between the studies, 22 (73.3%) could be considered morphological anomalies and eight (26.7%) as variants. This indicates that the chance of finding a morphological variantin the groupof patientswitha dis-crepancy in the assessed data waseight-fold higher than inthegroupwithoutdiscrepancy(OR:8;p<0.001;95%CI: 2.7---23.0).

Asthemorphologicalvariantsarecharacterizedbyhaving afrequencyabove4%andbyacontinuumofthe character-istic,itiseasytounderstandtheywillbemoredifficultto evaluate,andthereforemoresusceptibletothediscrepancy infrequencysurveydataintheliterature.

Study

limitations

The evaluation of the morphological characteristics was carriedoutbyonlyoneexaminerandonlyonce;therefore, it was not possible to rule out inter- or intraobserver

variations. Additionally, sample calculation was made basedonthepresenceofatleastoneminormorphological anomalyinthepopulationandnotonthefrequencyofeach them in particular; therefore, the differences not found between the different groups (when stratified by gender, agegroup,ethnicity,andwhencomparedtotheliterature) donot necessarily meanthat the groups are equal, since thedifferencemaynothavebeenobservedduetolackof statisticalpowertodetectthem.

Thepresentstudydeterminedandclassified morpholog-icalcharacteristicsinasample oftheBrazilianpopulation aged3---13years,sothatitwaspossibletodeterminewhatis avariantofnormalityandwhatisamorphologicalanomaly for this population. It showed that some morphological characteristics need tobestandardized tofacilitate their identification.

The study also demonstrated there is an important influence of age and ethnicity on the frequency of some characteristics;studieswithlargersamples,associatingage andethnicitytothefrequencyoftheidentified character-istics,arenecessarytoadequatelyclassifyamorphological characteristic.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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