Zygosity, Placental Membranes and Weinberg's Rule in a Danish Consecutive Twin Series

Husby, Henrik; Holm, Niels V.; Gernow, Anne; Thomsen, Sten Grove; Kock, Kirsten; Gürtler, H.

doi:10.1017/s0001566000002579

Cited by 32 publications

(23 citation statements)

References 7 publications

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“…In total, 66.4% of twin pairs were like sex in the UK, and 66.0% outside the UK. Zygosity proportions were calculated using the Weinberg rule: DZ pairs = 2 (unlike sex pairs) and MZ pairs = all pairs – (DZ pairs) 27,28. This meant that denominator data could be estimated for singleton, dizygotic and monozygotic twin deliveries.…”

Section: Methodsmentioning

confidence: 99%

Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening

Boyle

Morris

McConkey

et al. 2014

BJOG

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ObjectiveTo determine risk of Down syndrome (DS) in multiple relative to singleton pregnancies, and compare prenatal diagnosis rates and pregnancy outcome.DesignPopulation-based prevalence study based on EUROCAT congenital anomaly registries.SettingEight European countries.Population14.8 million births 1990–2009; 2.89% multiple births.MethodsDS cases included livebirths, fetal deaths from 20 weeks, and terminations of pregnancy for fetal anomaly (TOPFA). Zygosity is inferred from like/unlike sex for birth denominators, and from concordance for DS cases.Main outcome measuresRelative risk (RR) of DS per fetus/baby from multiple versus singleton pregnancies and per pregnancy in monozygotic/dizygotic versus singleton pregnancies. Proportion of prenatally diagnosed and pregnancy outcome.Statistical analysisPoisson and logistic regression stratified for maternal age, country and time.ResultsOverall, the adjusted (adj) RR of DS for fetus/babies from multiple versus singleton pregnancies was 0.58 (95% CI 0.53–0.62), similar for all maternal ages except for mothers over 44, for whom it was considerably lower. In 8.7% of twin pairs affected by DS, both co-twins were diagnosed with the condition. The adjRR of DS for monozygotic versus singleton pregnancies was 0.34 (95% CI 0.25–0.44) and for dizygotic versus singleton pregnancies 1.34 (95% CI 1.23–1.46). DS fetuses from multiple births were less likely to be prenatally diagnosed than singletons (adjOR 0.62 [95% CI 0.50–0.78]) and following diagnosis less likely to be TOPFA (adjOR 0.40 [95% CI 0.27–0.59]).ConclusionsThe risk of DS per fetus/baby is lower in multiple than singleton pregnancies. These estimates can be used for genetic counselling and prenatal screening.

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Section: Methodsmentioning

confidence: 99%

Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening

Boyle

Morris

McConkey

et al. 2014

BJOG

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show abstract

“…Monozygotic twins are same sex pairs with complete blood group concordance; <0.5% of dizygotic pairs have this concordance 9. Genomic DNA was prepared from peripheral blood lymphocytes and amplified by polymerase chain reaction.…”

Section: Methodsmentioning

confidence: 99%

Relative importance of genetic effects in rheumatoid arthritis: historical cohort study of Danish nationwide twin population Commentary: Do genes or environment influence development of rheumatoid arthritis?

Svendsen

2002

BMJ

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Objective To determine the relative importance of environmental and genetic effects in the development of rheumatoid arthritis. Design Historical cohort study with record linkage between a twin registry and the Danish discharge registry as well as the Danish national registry of deaths used to estimate completeness. Setting Two population based nationwide twin birth cohorts. Participants 37 338 twins were sent a questionnaire about rheumatic diseases. Self reported rheumatoid arthritis was verified by clinical examination and from medical records. Main outcome measures The probandwise concordance rate of rheumatoid arthritis in monozygotic and dizygotic twins. Results The response rate was 84.7%. Rheumatoid arthritis was verified in 13 monozygotic and 36 dizygotic twins. There were no concordant monozygotic twin pairs and two concordant dizygotic twin pairs. Based on capture-recapture methods the probability of ascertainment was 78.3%. The probandwise concordance rate was 0 (95% confidence interval 0 to 24.7) in monozygotic twins and 8.8 (1.9 to 23.7) in dizygotic twins. Conclusion Genes are of minor importance in the development of rheumatoid arthritis.

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“…The genetic markers included the following blood, serum, and enzyme types: ABO, MNS, RH, LEAB, HP, GC, PGM-l, ACP-l, GPT, ASD, and GLO. Twins were classified as monozygotic when all types were concordant (22).…”

Section: Methodsmentioning

confidence: 99%

Insulin secretion, insulin action, and hepatic glucose production in identical twins discordant for non-insulin-dependent diabetes mellitus.

Vaag¹,

Henriksen²,

Madsbad³

et al. 1995

J. Clin. Invest.

189

121

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12 identical twin pairs discordant for non-insulin-dependent diabetes mellitus (NIDDM) were studied for insulin sensitivity (euglycemic insulin clamp, 40 mU/m2 per min), hepatic glucose production (HGP, [3-3H] glucose infusion), and insulin secretion (oral glucose tolerance test and hyperglycemic [12 mM] clamp, including glucagon administration). Five of the nondiabetic twins had normal and seven had impaired glucose tolerance. 13 matched, healthy subjects without a family history of diabetes were included as control subjects. The NIDDM twins were more obese compared with their non-diabetic co-twins. The nondiabetic twins were insulin resistant and had a delayed insulin and C-peptide response during oral glucose tolerance tests compared with controls. Furthermore, the nondiabetic twins had a decreased first-phase insulin response and a decreased maximal insulin secretion capacity during hyperglycemic clamping and intravenous glucagon administration. Nondiabetic twins and controls had similar rates of HGP. Compared with both nondiabetic twins and controls, the NIDDM twins had an elevated basal rate of HGP, a further decreased insulin sensitivity, and a further impaired insulin secretion pattern as determined by all tests. In conclusion, defects of both in vivo insulin secretion and insulin action are present in non-and possibly prediabetic twins who possess the necessary NIDDM susceptibility genes. However, all defects of both insulin secretion and glucose metabolism are expressed quantitatively more severely in their identical co-twins with overt NIDDM. (J. Clin. Invest. 1995. 95:690-698.)

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Zygosity, Placental Membranes and Weinberg's Rule in a Danish Consecutive Twin Series

Cited by 32 publications

References 7 publications

Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening

Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening

Relative importance of genetic effects in rheumatoid arthritis: historical cohort study of Danish nationwide twin population Commentary: Do genes or environment influence development of rheumatoid arthritis?

Insulin secretion, insulin action, and hepatic glucose production in identical twins discordant for non-insulin-dependent diabetes mellitus.

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