Zygosity diagnosis in young twins by parental report

Abstract

Thi s study r epor ts on zygosi ty deter mi nati on i n tw i ns of chi l dhood age. Par ents r esponded to questionnaire items dealing with twin similarity in physical characteristics and frequency of mi stak i ng one tw i n for another by par ents, r el ati ves and str anger s. The accur acy of zygosi ty di agnosi s w as eval uated acr oss tw i ns aged 6, 8, and 10 and acr oss par ents. I n addi ti on, i t w as exami ned w hether the use of mul ti pl e r ater s and the use of l ongi tudi nal data l ead to an i mpr ovement of zygosi ty assi gnment. Compl ete data on zygosi ty questi ons and on geneti c mar k er s or bl ood pr ofi l es w er e avai l abl e for 618 tw i n pai r s at the age of 6 year s. The method used w as pr edi cti ve di scr i mi nant anal yses. A gr eement betw een zygosi ty assi gned by the r epl i es to the questi ons and zygosi ty deter mi ned by DNA mar k er s/bl ood typi ng w as ar ound 93%. The accur acy of assi gnment r emai ned constant acr oss age and par ents. A nal yses of data pr ovi ded by both par ents and col l ected over mul ti pl e ages di d not r esul t i n better pr edi cti on of zygosi ty. Detai l s on the di scr i mi nant functi on ar e pr ovi ded. Twin Research (2000) 3, 134-141. Keyw or ds: tw i n zygosi ty, chi l dhood, questi onnai re, revi ew, di scri mi nant anal ysi s I ntr oducti onIn 1927, Si emens 1 suggested that the di agnosi s of zygosi ty i n tw i ns can take pl ace by eval uati ng the degree of resembl ance on geneti cal l y determi ned trai ts. Devel opment of thi s method resul ted i n the frequent use of questi onnai res, often i ncl udi ng those cri teri a ori gi nal l y proposed by Si emens, for exampl e.2 Several studi es have show n that the establ i shment of zygosi ty based on mai l ed questi onnai res i s of consi derabl e accuracy, w i th around 95% correctl y cl assi fi ed compared w i th bl ood or DNA typi ng. Studi es on the di agnosi s of zygosi ty by mai l ed questi onnai res are summari sed i n A ppendi x 1.

Genetic and Environmental Effects on Weight, Height, and BMI Under 18 Years in a Chinese Population-Based Twin Sample

“…However, for convenience, assessing the extent to which co-twins look like each other using questionnaires is one of the most widely used methods for zygosity classification, especially in large sample studies like ours (Gao et al, 2006;Jackson et al, 2001). Many twin studies have shown that questionnaire-based zygosity diagnosis can achieve accuracy of around 93% (Rietveld et al, 2000).…”

Genetic and Environmental Influences on Individual Differences in Sleep Duration During Adolescence

“…These items allow accurate determination of zygosity in 93% of the same-sex twin pairs (Rietveld et al, 2000).…”

Body Size of Twins Compared with Siblings and the General Population: From Birth to Late Adolescence

“…We excluded data for several reasons: congenital anomalies (2 twins); severe growth retardation (1 sibling); non-Dutch parents (3 twin pairs); pregnancy or illness (weight data of 1 twin and 2 siblings); unavailability of weight and BMI reference values (28 siblings); unavailability of arm span reference values (7 twins and 23 siblings). Zygosity of same-sex twin pairs (145 pairs) was determined on the basis of DNA polymorphisms (140 pairs), blood group polymorphisms (4 pairs), or questionnaire items on similarity 21 (1 pair). The sample comprised 30 monozygotic male, 33 dizygotic male, 44 monozygotic female, 38 dizygotic female, and 39 dizygotic opposite sex twin pairs and 97 siblings (45% males and 55% females).…”