Mber of twin pairs unless otherwise noted, MZMC monozygotic monochorionic twins
Mber of twin pairs unless otherwise noted, MZMC monozygotic monochorionic twins, MZDC monozygotic dichorionic twins, DZDC Dizygotic dichorionic twins, BWT birth weight, MC monochorionic, DC dichorionic, MZ monozygotic, DZ dizygotic, EFPTS East Flanders Prospective Twin Survey, ICC intraclass correlation, BCG Bacille CalmetteGuerin vaccine, NCPP NINCDS Collaborative Perinatal Project, BMI physique mass index, LDL low density lipoprotein, HDL high density lipoprotein, NEFA nonesterified fatty acids, ICV intracranial volume, BWT birth weight, WISC Wechsler Intelligence Scale for Children, KABC Kaufmann Assessment Battery for Children, WAIS Wechsler Adult Intelligence Scale, CBCL Kid Behavior ChecklistBehav Genet Behav Genet in the course of childhood.When effects have been identified, MC twins have been frequently additional similar on the cognitive or personality assessment than DC twins have been, suggesting that for some cognitive measures heritability estimates may well be overestimated when not accounting for chorionicity.We identified 4 studies that PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21309039 examined other behavioral phenotypes.For measures of temperament in very early childhood, MC twin similarity was equal to DC twin similarity (Chen et al.; Riese).Similarly, there was no chorionicity impact on twin similarity for SIS3 web prosocial behavior or Youngster Behavior Checklist (CBCL) total troubles in childhood and adolescence (Hur ; Wichers et al).Hence, it is unlikely that chorionicity biases heritability estimates of toddler temperament and child and adolescent prosocial or problem behavior, despite the fact that the research had been very modest and few in number.DiscussionWe presented the state from the literature on twin chorionicity in relation to a series of human outcome traits, and addressed the query of to what extent chorionicity differences in MZ twins may influence heritability estimates.We discovered a sizable physique of literature on the effects of chorionicity on overall health and behavioral outcomes as well as a much smaller sized, but notable physique of literature ( articles in total) that examined chorionicity in relation to twin similarity, which could possibly be applied to draw tentative conclusions about no matter whether chorionicity could bias heritability estimates.With only 3 research from Asian populations and no research from African populations, we had been unable to draw even tentative conclusions about regardless of whether potential chorionicity biases may possibly differ in populations with different twinning rates and MZMCMZDCDZDC proportions.Constant with the theory that some chorionicity effects could bring about overestimation and other people to underestimation of heritability, there had been situations of each and every across the a lot of phenotypes deemed right here.On the other hand, firm conclusions ought to not be drawn considering that some of the outcomes were only examined in one or couple of studies and generally sample sizes were small.In this identical problem, van Beijsterveldt et al applying a sample of over twin pairs, report on chorionicity and heritability estimates on phenotypes, which includes weight, height, motor milestones, child difficulty behaviors, cognitive function, wellbeing and personality.For only a few traits, withinpair similarity differed amongst MCMZ and DCMZ pairs.For traits influenced by birth weight, which include weight in young young children MC twins have been extra discordant for out of measures.For traits exactly where blood provide is vital, MCMZ twins were a lot more concordant than DCMZ for traits.van Beijsterveldt et al.conclude that “the influence on the MZ twin correlation with the intrauterineprenatal atmosphere, as measured by sharing a cho.
