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Frontiers in Cellular and Infection... 2021The objectives are to estimate the vertical transmission rate in twins relative to singleton pregnancies, to evaluate whether discordance within twin pairs is rare, and...
OBJECTIVE
The objectives are to estimate the vertical transmission rate in twins relative to singleton pregnancies, to evaluate whether discordance within twin pairs is rare, and to characterize concordance within monozygotic and dizygotic twin pairs in relation to hereditability.
METHODS
We first sought to estimate the vertical transmission rate of congenital CMV infection in twins by gathering cohort-based studies of congenital CMV in which vertical transmission in both singleton and twin pregnancies was reported. This also allowed us to compare singleton and twin infection rates. From the above studies and other large cohorts of congenitally infected infants, the percentage of discordantly infected twin pairs determined whether this is a rare phenomenon. Theorizing discordance is not rare, we then analyzed data from cases with twin outcomes for congenital CMV infection, according to whether the twins were monozygotic or dizygotic, and calculated their corresponding concordance rates to estimate the broad-sense heritability. Lastly, we described other factors that might affect vertical transmission.
RESULTS
From five articles following at-risk pregnancies, the rate of vertical transmission in twin pregnancies is 58.7% (95% CI 43.3-72.3%) whereas in singleton pregnancies it is 31.4% (95% CI: 29.0-34.0%) = 0.0002. Of ten studies of larger cohorts of infants with congenital CMV infection, 21 of 42 twin pairs with at least one twin infected were discordant for congenital CMV (50.0%, 95% CI: 34.4-65.6%) indicating discordance of congenital CMV infection in twin pairs is not rare. Of 28 studies covering 37 twin pairs where at least one twin had congenital CMV, and zygosity was known, eleven of thirteen monozygotic twin pairs (84.6%; 95% CI: 53.7-97.3%) were concordant for CMV infection, and nine of twenty-four dizygotic twin pairs (37.5%; 95% CI: 19.6-59.2%) were concordant for infection giving an estimated hereditability of 94.2%. Within these 37 twin pairs, factors such as primary or recurrent maternal infection, prematurity, growth discordance, and sex are described; however, in many of these cases these factors are unknown.
CONCLUSION
The rate of vertical transmission of congenital CMV is higher for twins than singletons. Discordance of congenital CMV in twins is not rare and suggests a possible genetic susceptibility to congenital CMV.
Topics: Cytomegalovirus; Diseases in Twins; Female; Humans; Pregnancy; Pregnancy, Twin; Twins, Dizygotic; Twins, Monozygotic
PubMed: 34350131
DOI: 10.3389/fcimb.2021.676988 -
Hypertension in Pregnancy Nov 2016To determine whether the incidence of hypertensive disorders is different in monozygotic compared to dizygotic twin pregnancies.
OBJECTIVE
To determine whether the incidence of hypertensive disorders is different in monozygotic compared to dizygotic twin pregnancies.
METHODS
A registry-based survey of twin pregnancies delivered during 2003 to 2012. We used the best clinical estimate of zygosity based on the concept that all monochorionic twins are monozygotic and all unlike-sex pairs are dizygotic, thus excluding same-sex dichorionic twin gestations for which zygosity cannot be ascertained on clinical grounds. Study cohorts were twin pregnancies with or without preeclampsia and gestational hypertension.
RESULTS
A total of 3419 twin gestations met the inclusion criteria, of which 442 (12.9%) were monochorionic and 1255 (36.7%) were unlike-sex twins, excluding 1722 same-sex dichorionic twin gestations (50.4%). There was no significant difference in the incidence of preeclampsia (OR: 0.9; 95% CI: 0.4-2.0 for monozygotic males and OR: 0.6; 95% CI: 0.3-1.4 for monozygotic females) and gestational hypertension (OR: 0.7; 95% CI: 0.2-2.5 for monozygotic males, and OR: 0.7; 95% CI: 0.2-2.3 for monozygotic females) between monochorionic and unlike-sex pairs. Maternal prepregnancy obesity and nulliparity were the only significant associated factors of preeclampsia (OR: 3.8; 95% CI: 2.0-7.0, and OR: 2.5; 95% CI: 1.4-4.4, respectively). Maternal prepregnancy obesity (OR: 5.5; 95% CI: 2.5-12.2), maternal age ≥36 years (OR: 2.5; 95% CI: 1.1-6.1), and family history of hypertension (OR: 2.6; 95% CI: 1.3-5.1) were significantly associated with gestational hypertension.
CONCLUSION
Based on a large population-based dataset and on the best clinical estimate of twin zygosity, it appears that zygosity is not associated with hypertensive disorders in twin gestations.
Topics: Adult; Female; Humans; Hypertension, Pregnancy-Induced; Incidence; Male; Pregnancy; Pregnancy, Twin; Sex Factors; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 27420020
DOI: 10.1080/10641955.2016.1197936 -
Twin Research and Human Genetics : the... Apr 2022It is widely recognized that dizygotic twinning (DZT) runs in families, but estimates of heritability from twin and family data are remarkably scarce and vary...
It is widely recognized that dizygotic twinning (DZT) runs in families, but estimates of heritability from twin and family data are remarkably scarce and vary considerably. Here, we traced seven large, sometimes historical, multigeneration pedigrees from West Africans, fin de siècle French Jews, Canadians (two pedigrees), and the French royal family, in which twin births were recorded. We estimated heritability of twinning (of all types) as zygosity information was not available, diluting the true DZT heritability by a third or so. The estimates in the range 8-20% are remarkably consistent across time (8-19 generations) and ethnicities and also consistent with twin and family estimates.
Topics: Canada; Humans; Pedigree; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35593089
DOI: 10.1017/thg.2022.14 -
Pediatrics Mar 2016Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the femoral head. Its etiology is poorly understood, although previous studies have implicated...
BACKGROUND
Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the femoral head. Its etiology is poorly understood, although previous studies have implicated low birth weight and possible genetic determinants. The aim of this study was to identify potential birth weight and genetic associations with LCPD.
METHODS
We extracted all twin pairs from the Danish Twin Registry (DTR) in which at least 1 individual had LCPD. The DTR captures every twin pair born alive in Denmark, and those with LCPD were identified by using health record linkage. Probanwise concordance was calculated to describe the likelihood that any given individual had LCPD if their co-twin was also diagnosed.
RESULTS
There were 81 twin pairs: 10 monozygotic, 51 dizygotic, and 20 unclassified (unknown zygosity [UZ]). There was no association between birth weight and being the affected co-twin. Four pairs (2 dizygotic and 2 UZ) were concordant for LCPD, which is greater than would be expected assuming no familial aggregation. There were no concordant monozygotic twin pairs. The overall probandwise concordance was 0.09 (95% confidence interval [CI]: 0.01-0.18): 0.00 for the monozygotic, 0.08 (95% CI: 0.00-0.18) for the dizygotic, and 0.18 (95% CI: 0.00-0.40) for the UZ twin pairs.
CONCLUSIONS
This study found evidence of familial clustering in LCPD but did not show a genetic component. The absolute risk that a co-twin of an affected individual will develop LCPD is low, even in the case of monozygotic twin pairs.
Topics: Child; Child, Preschool; Denmark; Diseases in Twins; Female; Genetic Predisposition to Disease; Humans; Incidence; Legg-Calve-Perthes Disease; Male; Retrospective Studies; Twins, Dizygotic; Twins, Monozygotic
PubMed: 26908702
DOI: 10.1542/peds.2015-3542 -
Twin Research and Human Genetics : the... Dec 2019The South Korean Twin Registry (SKTR) is an ongoing nationwide volunteer registry of South Korean twins and their families. Since its inception, from preschooler to...
The South Korean Twin Registry (SKTR) is an ongoing nationwide volunteer registry of South Korean twins and their families. Since its inception, from preschooler to young adult, twins have been registered with the SKTR and have demonstrated that relative influences of genetic and environmental factors explaining individual differences in various psychological, mental health and physical traits in South Koreans are similar to those found in many Western twin studies. Currently, studies at the SKTR focus on identification of the process of gene-by-environment interactions as well as developmental differences in genetic and environmental influences on psychological and mental health traits in South Koreans. This report provides a brief overview, recruitment strategies, current samples, zygosity assessment, measures and future directions of the SKTR.
Topics: Adolescent; Adult; Child; Diseases in Twins; Female; Follow-Up Studies; Gene-Environment Interaction; Humans; Male; Models, Genetic; Registries; Republic of Korea; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 31875802
DOI: 10.1017/thg.2019.115 -
Clinical Nutrition (Edinburgh, Scotland) Apr 2019While environmental factors are presumed to be primary drivers of food timing, preliminary evidence suggests that genetics may be an additional determinant. The aim was... (Observational Study)
Observational Study
BACKGROUND & AIMS
While environmental factors are presumed to be primary drivers of food timing, preliminary evidence suggests that genetics may be an additional determinant. The aim was to explore the relative contribution of genetics and environmental factors to variation in the timing of food intake in a Spanish twin population. Because chronotype, bedtime and wake time are related to food timing, covariance with food timing was further assessed.
METHODS
In this observational study, 53 pairs of adult (mean (SD) = 52 (6.03) years) female twins (28 monozygotic; 25 dizygotic) were recruited from the Murcia Twin Register. Zygosity was determined by DNA-testing. Timing of the three main meals of the day was assessed via 7-day dietary records, and the midpoint of food intake was computed by calculating the midpoint between breakfast and dinner times. Chronotype, bedtime and wake time were self-reported. Heritability of food timing and related traits were estimated by comparing monozygotic and dizygotic twin correlations and fitting genetic structural equation models to measured variables.
RESULTS
We observed genetic influences for food timing, with highest heritability for the midpoint of food intake (64%) in an overweight/obese population (BMI = 26.01 ± 3.77). Genetic factors contributed to a higher degree to the timing of breakfast (56%) than the timing of lunch (38%) or dinner (n.s.). Similarly, heritability estimates were larger in related behavioral traits earlier on in the day (i.e. wake time, (55%)), than those later on in the day (i.e. bedtime, (38%)). Bivariate analyses revealed a significant genetic overlap between food timing and bedtime and chronotype (rG between 0.78 and 0.91).
CONCLUSIONS
Genetic influences appear to account for a significant proportion of the variability in food timing, particularly breakfast. Thus, interventions related to food timing may be more effective when targeting afternoon/evening traits, such as lunch or dinner times. Furthermore, our data suggest shared genetic architecture underlying food timing and phenotypically related traits.
CLINICAL TRIAL
NCT03059576. https://clinicaltrials.gov/ct2/show/NCT03059576.
Topics: Aged; Diet; Eating; Environment; Feeding Behavior; Female; Humans; Male; Middle Aged; Time Factors; Twins, Dizygotic; Twins, Monozygotic
PubMed: 29571565
DOI: 10.1016/j.clnu.2018.03.002 -
Annals of Human Genetics Jan 2017Genome-wide association studies with moderate sample sizes are underpowered, especially when testing SNP alleles with low allele counts, a situation that may lead to...
Genome-wide association studies with moderate sample sizes are underpowered, especially when testing SNP alleles with low allele counts, a situation that may lead to high frequency of false-positive results and lack of replication in independent studies. Related individuals, such as twin pairs concordant for a disease, should confer increased power in genetic association analysis because of their genetic relatedness. We conducted a computer simulation study to explore the power advantage of the disease-concordant twin design, which uses singletons from disease-concordant twin pairs as cases and ordinary healthy samples as controls. We examined the power gain of the twin-based design for various scenarios (i.e., cases from monozygotic and dizygotic twin pairs concordant for a disease) and compared the power with the ordinary case-control design with cases collected from the unrelated patient population. Simulation was done by assigning various allele frequencies and allelic relative risks for different mode of genetic inheritance. In general, for achieving a power estimate of 80%, the sample sizes needed for dizygotic and monozygotic twin cases were one half and one fourth of the sample size of an ordinary case-control design, with variations depending on genetic mode. Importantly, the enriched power for dizygotic twins also applies to disease-concordant sibling pairs, which largely extends the application of the concordant twin design. Overall, our simulation revealed a high value of disease-concordant twins in genetic association studies and encourages the use of genetically related individuals for highly efficiently identifying both common and rare genetic variants underlying human complex diseases without increasing laboratory cost.
Topics: Computer Simulation; Diseases in Twins; Gene Frequency; Genetic Predisposition to Disease; Genome-Wide Association Study; Humans; Models, Genetic; Risk; Twins, Dizygotic; Twins, Monozygotic
PubMed: 28009044
DOI: 10.1111/ahg.12181 -
Twin Research and Human Genetics : the... Dec 2019The Boston University Twin Project (BUTP) uses a multimethod, longitudinal approach to study the role of genetic and environmental factors on the development of child... (Clinical Trial)
Clinical Trial
The Boston University Twin Project (BUTP) uses a multimethod, longitudinal approach to study the role of genetic and environmental factors on the development of child temperament and related behaviors in early childhood. There are two phases in this project. The first, described in the previous Twin Research and Human Genetics special issue on twin registries, focused on activity level and comprised over 300 twin pairs assessed in the home and laboratory at ages 2 and 3. In this article, we describe subject recruitment, sample characteristics, and study procedures and measures of the second phase of the BUTP. This recent study focuses more broadly on the development of multiple temperament dimensions and explores associations between temperament trajectories, parenting and child adjustment in a new cohort of approximately 300 twin pairs assessed at 3, 4 and 5 years of age.
Topics: Child; Female; Humans; Male; Temperament; Twins, Dizygotic; Twins, Monozygotic; Universities
PubMed: 31514760
DOI: 10.1017/thg.2019.58 -
Twin Research and Human Genetics : the... Feb 2022Heritability of age at menarche (AAM) in African populations remains largely unknown. A question on AAM was given to 1803 [454 monozygotic (MZ), 823 same-sex dizygotic...
Heritability of age at menarche (AAM) in African populations remains largely unknown. A question on AAM was given to 1803 [454 monozygotic (MZ), 823 same-sex dizygotic (DZ), and 526 female members of opposite sex] adolescent twins attending public schools in Lagos State, Nigeria. The age range of the sample was 12-18 years, with a mean (SD) of 14.57 (±1.70) years. The data included 905 missing cases consisting of those who had not experienced menarche and did not recall AAM. Missing values were imputed using the Expectation-Maximization algorithm. Kaplan-Meier analysis based on the imputed data yielded 13.23 years [95% CI [13.18, 13.28] for the mean and 13.00 years [95% CI [12.96, 13.04] for the median of AAM. Twin correlation and model-fitting analyses were performed on the basis of those who reported AAM (MZ = 82 complete pairs and 38 cotwin missing cases; DZ = 157 complete pairs and 99 cotwin missing cases). Maximum likelihood MZ and DZ twin correlations for AAM were .63 (95% CI [.48, .74]) and .33 (95% CI [.19, .45]) respectively. Model-fitting analyses indicated that 58% (95% CI [46, 67]) of the variance of AAM was associated with additive genetic influences with the remaining variance, 42% (33-54) being due to nonshared environmental influences including measurement error. The heritability estimate found in this study was within the range of those found in Asian and Western twin samples.
Topics: Adolescent; Asian People; Child; Female; Humans; Menarche; Nigeria; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35535435
DOI: 10.1017/thg.2022.9 -
Journal of Perinatology : Official... Jun 2018Abnormal umbilical cord coiling is associated with adverse perinatal outcomes; however, the etiology of the umbilical coiling pattern is poorly understood. (Comparative Study)
Comparative Study
OBJECTIVE
Abnormal umbilical cord coiling is associated with adverse perinatal outcomes; however, the etiology of the umbilical coiling pattern is poorly understood.
STUDY DESIGN
Retrospective cohort of all twin deliveries >20 weeks in 2014. Pregnancies were dichotomized by chorionicity and the umbilical coiling index (UCI) and placental cord insertion location were compared. In cases with one or both cords hypercoiled, the direction and pattern of coiling were compared by chorionicity. A similar analysis was performed stratified by zygosity.
RESULTS
Three hundred sisty two twin pairs were included; 26 (7.2%) monochorionic and 174 (87.0%) definitively dizygotic. Concordance in the UCI and coiling category were similar between dichorionic and monochorionic as well as dizygous and monozygous gestations, (73.2% vs 80.8%, p = 0.399 and 71.4% vs 80.8%, p = 0.399, respectively). Analyses of the coiling direction and pattern also demonstrated no difference by chorionicity or zygosity.
CONCLUSION
These data do not support a genetic basis for umbilical cord coiling.
Topics: Cohort Studies; Female; Genetic Predisposition to Disease; Humans; Infant, Newborn; Live Birth; Male; Pregnancy; Pregnancy, Twin; Retrospective Studies; Risk Assessment; Statistics, Nonparametric; Twins, Dizygotic; Twins, Monozygotic; Ultrasonography, Prenatal; Umbilical Cord
PubMed: 29467518
DOI: 10.1038/s41372-018-0078-y