Elena L. Grigorenko
Commentary: Translating quantitative genetics into molecular genetics: decoupling reading disorder and ADHD – reflections on Greven et al. and Rosenberg et al. (2012)
Yale University
articles greven colleagues greven rijsdijk asherson plomin 2012 rosenberg colleagues rosenberg pennington willcutt olson 2012 presented issue focused well established still unexplained observationthat specific reading disability srd attention deficithyperactivity disorder adhd cooccur individuals much often would expected chance given population rates developmental disorders articles provide brief overviews research cooccurrence summarizing reader known prior publication previously asserted based empirical evidence presented mostly groups ie uk twins early development study teds colorado learning disabilities research center cldrc also researchers cooccurrence attributable primarily shared genetic risk factors although magnitude stability across lifespan unclear relationships srd adhd homogeneous srd appears associated closely inattentive adhdi hyperactive adhdh symptom dimension adhd two articles attempt take understanding complex relationships srd adhd forward specifically teds contribution greven et al 2012 using two measurement time points middle childhood early adolescence srd adhd attempts decompose genetic sharedness considering stabilitychangeability time shed light causal relationships two disorders concludes genetic factors substantiating sharedness indeed quite stable across two time points suggesting although specific genes seem involved manifestation disorders time point genes substantiating cooccurrence srd adhd stable moreover although reciprocal relationships srd adhd observed across middle childhood early adolescence relationships biased adhd symptoms found significantly stronger predictor indicators reading performance vice versa finally article also avows although exhibited significant genetic correlations reading indicators correlations inattentiveness stronger correlations hyperactivity cldrc contribution rosenberg et al 2012 places within context growing field gene environment interactions circumscribing subset socalled heritability environment interaction studies environmental genetic factors measured article attempts differentiate two types interactions asserting parent education interacts heritability srd adhd discrepantly former heritability estimates appear stronger higher level parental education whereas latter appear stronger lower authors contextualize observations typologizing bioecological interaction srd diathesisstress interaction adhd emphasizing opposite directions given wealth data theoretical considerations presented two articles specific lines thought might point view capture attention reader might lines albeit limited selection given constraints commentary linked broader field provides particular impetus propelling field forward among many lines chosen three discuss briefly first although fact srdadhd cooccurrence well known still securely established psychological texture cooccurrence reasoned perhaps distinct psychological trait function process number traits whose deficiencies present disorders srd adhd traitcandidate might processing speed mcgrath et al 2011 yet concept processing speed complex moreover consensus regarding content measurement still field ever unifies around consistent assessment batteries used systematically explore phenotypic manifestations various disorders overlaps would important test using numerous hopefully large samples whether foundation traits may viewed polyphenotypes ie phenotypes constituting core deficits one disorder whose psychological texture could account comorbidity developmental disorders whose genetic architecture could account estimated genetic correlations disorders second doubt empirical indicators presence differential role parental education theoretical discourse heritabilityparental education interactions srd adhd great interest challenge however try bridge statistical presentation observations interactions although substantiated impressive modeling machine schematas biological mechanism may drive interaction clearly sooner later hypotheses depicting specific mechanisms yet absence speculative discourses interactions might forgivable three points seem important first given current unresolved discrepancy high heritability estimates obtained quantitativegenetic studies difficulty success translating heritability estimates molecular mechanisms moleculargenetic studies eichler et al 2010 manolio et al 2009 rather likely molecular specifics interactions going slow coming second parental education reflects conglomerate sources variance eg standards living dietary preferences physical activity patterns childrens current educational context home literacy environment might change patterns expression human genome general parts engaged directly indirectly development manifestation srd adhd particular third today rather difficult hypothesize genomes risk adhd heritability adhd goes coupled lower parent education similarly stage nearimpossible imagine mechanistically heritability srd goes combined high levels parental education based know genome responsiveness environmental context know fluctuations principle possible yet point really difficult predict might correspondingly likely least finding remain interesting quantitativegenetic finding untranslated perhaps even untranslatable specific moleculargenetic mechanism finally particularly intriguing thread thought pertains idea hypothesizing molecular mechanismbackground might assuring genetic change vs stability development molecular reality substantiates statement genetic innovations well stable genetic factors trait molecular mechanisms epigenetic alternative splicing alterations transcriptome varki geschwind eichler 2008 might engaged providing moleculargenetic reality quantitative genetic observations committed mechanisms particular conditionssrd adhd mechanisms thought relevant comorbid disorders interesting duet articles quantitativegenetic nature although elegant present reader observations limited constraints models quantitative genetics observations insightful interesting checked literal biological rather metaphoric statistical meaning taken new level field environment ie parental education also genome measured author declared competing potential conflicts interest relation invited commentary article elena l grigorenko child study center departments psychology epidemiology public health yale university 230 south frontage road new ct 065191124 usa tel 1 2037372316 fax 1 2037853002 website httpwwwyaleedueglab email email protected