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Conjoined twins (Siamese twins) represent the rarest form of twin pregnancy. Reported here are two rare cases of conjoined term twins presented to the department of Obstetrics and Gynaecology within 3 months. The first case, 32 years of gravida 6 parity 5 referred from periphery after full trial of labour following multi-organ dysfunction and term intrauterine dead twins. Intraoperatively it was dead conjoined thoraco-omphalopagus females. The patient died after 3 days following multiorgan dysfunction syndrome and disseminated intravascular coagulation. The second case, 22 years gravida 2 parity 1 also referred from periphery in second stage of labour with diagnosis of 39 weeks intrauterine dead twins with obstructed labour, delivered by caesarean with intraoperative conjoined dead females of thoracophagus type. Twins are high-risk pregnancy. This rare diagnosis with complications could have been prevented by regular antenatal checkups, ultrasonography performed by radiologists and early referral antenatally in labour along with multidisciplinary approach.

Twin-twin transfusion syndrome occurs in multiple gestations and involves a chronic flow of blood from one twin to another twin and is a rare entity. We present a case of 32-years-old primigravida with a twin pregnancy who presented with increasing abdominal girth inappropriate with her gestational age at 21 weeks of her pregnancy. Ultrasound findings were suggestive of twin-twin transfusion syndrome. The patient was provided with treatment options but due to polyhydramnios and short cervix, the patient went into spontaneous labour the same day with a poor pregnancy outcome. Twin-twin transfusion syndrome leads to a high rate of perinatal morbidity due to its poorly understood aetiology and difficulty in diagnosing and treatment. Early diagnosis during antenatal ultrasound is important in reducing morbidity and mortality rates.

Background: Although alterations in medial temporal lobe structures have been previously associated with use of cannabis, one of the most widely used illicit drugs, whether such alterations are a cause or effect of cannabis use has been unclear. Methods: In this cross-sectional observational study involving 404 twins/siblings, we have compared cortical thickness and surface area between groups of gender-matched sibling-pairs (concordant cannabis unexposed, concordant exposed and discordant for cannabis exposure) using permutation tests after controlling for potential confounds. Bi-variate polygenic model was used to assess the genetic and environmental contributions underlying cortical morphological phenotypes and frequency of cannabis use. Results: Cortical thickness of the right entorhinal cortex was significantly lower in the concordant exposed siblings compared to both discordant unexposed and discordant exposed groups [false discovery rate (FDR)-corrected, q < 0.05]. The association between the right entorhinal cortex thickness and frequency of cannabis use is due to the contribution of significant shared additive genetic (ρ g = −0.19 ± 0.08; p = 0.02) factors but not unique environment (ρ e = 0.05 ± 0.09; p = 0.53). Significantly lower surface area of the right entorhinal cortex in discordant exposed group compared with the discordant unexposed group furnishes preliminary evidence in support of causal effect of cannabis use (FDR-corrected, q < 0.05). However, bi-variate polygenic model-based analysis did not show any significant effect. Conclusions: Shared genetic liability may underlie the association between cannabis exposure and thinner right entorhinal cortex. Prospective longitudinal studies are necessary to definitively disentangle the cause–effect relationships of cannabis use. [ABSTRACT FROM AUTHOR]

This report describes a rare case of conjoined female twin monster (Monocephalus Thoracopagus Tetrabrachius Tetrapus Dicaudatus) in a Holstein Friesian pluriparous crossbred cow.

The hypothesis was tested that musical creative achievement and musical practice are associated with lower alexithymia. 8000 Swedish twins aged 27-54 were studied. Alexithymia was assessed using the Toronto Alexithymia Scale (TAS-20). Musical achievement was rated on a 7-graded scale. Participants estimated number of hours of music practice during different ages throughout life. A total life estimation of number of accumulated hours was made. They were also asked about ensemble playing. In addition, twin modelling was used to explore the genetic architecture of the relation between musical practice and alexithymia. Alexithymia was negatively associated with (i) musical creative achievement, (ii) having played a musical instrument as compared to never having played, and – for the subsample of participants that had played an instrument – (iii) total hours of musical training (r = -.12 – in men and -.10 in women). Ensemble playing added significant variance. Twin modelling showed that alexithymia had a moderate heritability of 36% and that the association with musical practice could be explained by shared genetic influences. Associations between musical training and alexithymia remained significant when controlling for education, depression, and intelligence. Musical achievement and musical practice are associated with lower levels of alexithymia in both men and women. Musical engagement thus appears to be associated with higher emotional competence, although effect sizes are small. The association between musical training and alexithymia appears to be entirely genetically mediated, suggesting genetic pleiotropy.

Objectives. We aimed to examine associations between each of three leisure activities (Cognitive, Physical, and Social) and performance in selected cognitive domains (Speed, Memory, Verbal ability, and Executive functions) and global cognition. We also aimed to explore associations between medical and health factors and late-life cognition. Method. Our sample comprised 119 pairs of monozygotic twins from the Older Australian Twins Study. Their mean age was 71 years and 66% were women. We used a discordant co-twin design, with cognitive performance measures as dependent variables and leisure activities as independent variables. Multiple regression analyses were performed, adjusting for potentially relevant medical and health factors. Results. Discordance in Cognitive Activity and Social Activity participation was positively associated with discordance in performance on some cognitive domains. There were no associations between Physical Activity participation and cognition. Discordance in several cardiovascular, frailty, and sensory variables was associated with discordance in cognitive performance measures. Discussion. This study identified lifestyle and health-related influences on late-life cognition. Our findings not only help in understanding the neurobiological mechanisms, they also have practical implications for interventions to prevent or slow age-related cognitive decline. [ABSTRACT FROM PUBLISHER]

ABSTRACT Aims To investigate the relative contribution of genetic and environmental factors on smoking trajectory membership and to test whether individual smoking trajectories represent phenotypical thresholds of increasing genetic risk along a common genetic liability dimension. Design Prospective study of a birth cohort of female like-sex twin pairs. Setting Participants completed diagnostic interview surveys four times from adolescence (average age 16) to young adulthood (average age 25). Participants Female twins who had smoked ≥100 cigarettes life-time ( n = 1466 regular smokers). Measurements Number of cigarettes smoked per day during the heaviest period of smoking (two waves) or during the past 12 months (two waves). Findings A four-trajectory class solution provided the best fit to cigarette consumption data and was characterized by low ( n = 564, 38.47%), moderate ( n = 366, 24.97%) and high-level smokers ( n = 197, 13.44%), and smokers who increased their smoking from adolescence to young adulthood ( n = 339, 23.12%). The best genetic model fit was a three-category model that comprised the low, a combined increasing + moderate and high trajectories. This trajectory categorization was heritable (72.7%), with no evidence for significant contribution from shared environmental factors. Conclusions The way in which smoking patterns develop in adolescence has a high level of heritability. [ABSTRACT FROM AUTHOR]

This study used genome-wide linkage analysis to detect Quantitative Trait Loci (QTLs) implicated in variation in general academic achievement as measured by the Queensland Core Skills Test (QCST) (Queensland Studies Authority, 2004). Data from 210 families were analysed. While no empirically derived significant or suggestive peaks for general academic achievement were indicated a peak on chromosome 2 was observed in a region where Posthuma et al. (2005) reported significant linkage for Performance IQ (PIQ) and suggestive linkage for Full Scale IQ (FSIQ), and Luciano et al. (this issue) observed significant linkage for PIQ and word reading. A peak on chromosome 18 was also observed approximately 20 cM removed from a region recently implicated in reading achievement. In addition, on chromosomes 2 and 18 peaks for a number of specific academic skills, two of which were suggestive, coincided with the general academic achievement peaks. The findings suggest that variation in general academic achievement is influenced by genes on chromosome 2 which have broad influence on a variety of cognitive abilities. [ABSTRACT FROM AUTHOR]

Previous studies of the genetic and environmental components of the Family Environment Scale (FES) have typically reported that scales relating to familial acceptance are moderately to strongly genetically influenced while measures of control are more environmentally influenced. These reports relied on retrospective recall, which is not as reliable as recall of current environment. To investigate the genetic contribution to contemporaneous perceptions of one’s rearing environment, the responses on the FES of 471 17-year-old male twins (141 complete MZ twin pairs, 73 complete DZ twin pairs, 43 incomplete twin pairs) participating in the Minnesota Twin-Family Study (MTFS) were analyzed. Individual FES scales were generally modestly to moderately heritable. Unlike previous research, we did not find evidence that measures of control/structure were less heritable than measures of acceptance/support. These findings support a genetic basis of perceptions of one’s family environment and indicate that reports of control/structure may be more genetically influenced than previously believed based on retrospective reports. [ABSTRACT FROM AUTHOR]

The role of visual cues in individual agemate discrimination by lambs (Ovis aries) was assessed in two experiments. Lambs in the initial experiment were tested in pairs in a dark room, thereby eliminating access to the partners' visual phenotypes. When tested with a familiar penmate, lambs bleated less than did those paired with an unfamiliar unrelated partner, which implies that the penmates were recognized despite the absence of visual cues. In the second experiment, lambs were exposed individually to a projected life-size image of a familiar penmate (F), their (familiar) twin (T) or an unfamiliar unrelated lamb (U). The subject lambs responded in a more positive manner to the T slide than to a U image, however the F and U images did not elicit differential reactions. Visual cues thus appeared to be a sufficient basis only for twin recognition in this context. These results were compared to data from related studies concerning the roles of audition and olfaction in social discrimination by lambs. [ABSTRACT FROM AUTHOR]

Purpose: To characterize status epilepticus (SE) and estimate its frequency of first occurrence, as well as to assess the contribution of genetic factors to risk of SE occurrence in a sample of Virginia-born twins ascertained from the population-based Mid-Atlantic Twin Registry. Methods: The occurrence of SE was determined in 13,506 unselected Virginia-born twin pairs ascertained from birth records. Twins included in the study were between ages 2 and 75 years when surveyed. History of seizures and SE was validated through medical records and by detailed personal or parental interviews. Results: Among 381 twins included in 332 pairs with a verified history of seizures, 70 (18.4%) were validated to have had at least one episode of SE. The frequency of first SE in this sample was 309 per 100,000 twins. First SE occurred in conjunction with 21 of 158 febrile and 49 of 223 afebrile seizure cases, respectively. Mean length of SE episode was 76.2 ± 14.9 min. Age at first SE occurrence ranged from 2 months to 59 years. All concordant twin pairs in the sample were monozygotic (MZ), with a proband-wise concordance rate estimated for SE in this population of 0.31 [95% confidence interval (CI), 0.14–0.52) overall, and 0.67 (95% CI, 0.35–0.90) in pairs concordant for epilepsy. Conclusions: These results provide a direct estimate of the frequency of SE in a defined population of twins and afford further evidence for a genetic contribution to risk for SE. [ABSTRACT FROM AUTHOR]

Summary Polymorphic light eruption is classified as an acquired idiopathic photodermatosis, yet it appears to cluster in families, suggesting a possible genetic component. In this study, we assess the heritability of polymorphic light eruption using the classical twin model. Polymorphic light eruption was investigated by a nurse-administered questionnaire in a sample of 420 pairs of adult female twins from St Thomas' Hospital UK Adult Twin Registry, including 119 monozygotic and 301 dizygotic pairs. Probandwise concordance for the presence and absence of disease was calculated and the heritability of polymorphic light eruption assessed by a quantitative genetic model fitting approach using Mx software. The prevalence of polymorphic light eruption was 21% and 18% in monozygotic and dizygotic twins, respectively. A family history of polymorphic light eruption in first-degree relatives (not including the cotwin) was present in 12% of affected twin pairs (where at least one twin had polymorphic light eruption) compared with 4% of unaffected twin pairs, providing evidence of familial clustering (p < 0.0001). The probandwise concordance for polymorphic light eruption was higher in monozygotic (0.72) than in dizygotic twin pairs (0.30), indicating a strong genetic effect. Quantitative genetic modeling found that a model comprising additive genetic (A) and unique environmental (E) factors provided the most parsimonious fit, although a dominant gene effect could also explain our data. In the AE model, 84% (95% confidence interval 65–94%) of the variance in susceptibility to polymorphic light eruption is attributed to additive genetic factors with the remaining 16% (95% confidence interval 6–35%) to unique environmental effects. These data establish a clear genetic influence in the expression of polymorphic light eruption and provide a basis for examining candidate genes that may be pathogenic in this common condition. [ABSTRACT FROM AUTHOR]

The aims of this study were to determine the frequency of hypodontia of permanent teeth in twins discordant or concordant for clefts in each type of cleft, to determine the concordance of hypodontia in mono- and dizygotic twins, and to compare the findings with some earlier data. Thirty-nine pairs of twins between 7 and 23 yr of age were investigated. Six of 13 monozygotic and 24/26 dizygotic pairs were discordant for clefts. Orthopantomograms of the dentition, treatment records, and anamnestic data were studied. Twenty-three pairs of twins (59%) had at least one twin with hypodontia: 9/13 (69%) monozygotic and 14/26 (54%) dizygotic. The prevalence of hypodontia was 37% for monozygotic and 32.7% for dizygotic twins, 16.7% in the noncleft and cleft lip groups, 41.1% in the cleft palate group, and 64.3% in the cleft lip and palate group. All these were above the values observed earlier in the noncleft twins and in the Finnish normal and cleft group populations. Four of 13 pairs of monozygotic twins had no hypodontia, 8/9 pairs were discordant, and only 1/9 was concordant for hypodontia. The corresponding figures for the 26 dizygotic pairs were: 12/26, 11/14, and 3/14 pairs. Maxillary second premolars were the most frequently absent teeth, followed in order of frequency by the maxillary lateral incisors and the mandibular second premolars. Hence, for this sample of twins, the genetic component seems to be weak. [ABSTRACT FROM AUTHOR]

The aims of this investigation were: 1) to study the effects of zygosity and the type of cleft on dental age in pairs of twins concordant or discordant for oral clefts, 2) to compare dental age in the twins with that in a population of normal Finnish children, and 3) to study asymmetry in the formation of mandibular teeth with regard to zygosity and the type of cleft. Twenty-two pairs of twins (8 mono- and 14 dizygotic) and one set of monozygotic triplets concordant or discordant for deft lip (CL), cleft palate (CP), or both (CLP) were investigated. Four of eight mono- and 12 of 14 dizygotic pairs were discordant for clefts. An orthopantomogram of both twins was taken on the same day. In 7 of the 8 monozygotic (88%) and in 4 of the l4 dizygotic (29%) pairs, the dental age was the same in both twins. Of the 12 pairs discordant for clefts, the dental age of the twin with cleft was delayed in 5, advanced in 3, and the same in 4 compared with that of the twin without a deft. The means of chronologic age and dental age were counted separately for the cleft subgroups and the non-cleft (NONC) group. The dental age was advanced in the CL twins and in the NONC twins, and was the same as chronologic age in the CP twins, but it was delayed in the CLP twins. Asymmetric formation of the 14 mandibular teeth (mostly the second premolars) was encountered in 3 of 8 CLP in 3 of 18 CP, in 1 of 16 NONC, and in none of 5 CL children. The great similarity in tooth formation among the monozygotic twins indicates strong genetic control of dental maturation in twins concordant and also discordant for cleft. [ABSTRACT FROM AUTHOR]

Results obtained from the Colorado Twin Study of Reading Disability provide compelling evidence for a genetic etiology. For the present report, multiple regression analyses were performed on reading performance data from 186 pairs of identical twins and 138 pairs of same-sex fraternal twins among whom at least one member of each pair has a reading disability. The results indicate that on average, more than half of the reading performance deficit of probands is a consequence of heritable influences. Moreover, individual differences within the affected twin sample are highly heritable, whereas shared environmental influences do not contribute importantly to twin resemblance. The results of these analysis also suggest that the etiology of reading performance. Because the estimate of heritability for reading performance in affected twin pairs is substantially higher than that in a control sample, reading disability may be caused be one or more genes having major effects. These results are highly consistent with our recent report of a putative quantitative trait locus for reading disability in a small region on the short arm of chromosome 6. [ABSTRACT FROM AUTHOR]

The article presents information on a study that examines the familial and nonfamilial influences on cognitive achievement and academic performance in twins. The analysis is based on data taken from the High School and Beyond Study. The study gathered base-year data on high school seniors and sophomores, using a nationally representative stratified random sample of public, private, and church-affiliated schools. The analysis is conducted on 355 twin pairs (710 siblings) with complete data on the variables of interest. The results indicate considerable symmetry in both cognitive achievement and academic performance for sets of twins distinguished according to gender composition. For cognitive achievement, there are no variations in the underlying factor structure. Factor loadings and error variances are uniform across types of twin pairs. Similarly, there are no differences in the way twins within a family respond to the common family, environment for cognitive achievement. The results also indicate that there is substantially more between-family variation in cognitive achievement than academic performance.

Background: Hearing deterioration at advanced ages is associated with environmental exposures (eg, to noise and solvents) and genetic influences may also be important. Little is known about the role of genetic influences on hearing when evaluated longitudinally. We sought to investigate longitudinal hearing loss in a cohort of adult male twins to evaluate the importance of genetic and environmental factors for hearing deterioration over time., Methods: Hearing using conventional clinical audiometry was assessed in 583 male twins (128 monozygotic twin pairs and 111 dizygotic twin pairs) aged 34-79 at baseline and again two decades later. The hearing thresholds at two time points were compared at each frequency and in two different frequency regions. Genetic analyses were based on structural equation models. Bivariate Cholesky decomposition was used for longitudinal analysis., Results: The prevalence of hearing loss increased over time in better and worse ear. The hearing threshold shift was more pronounced in the high-frequency region, especially at 8000 Hz. Genetic influences were moderate (heritability: 53%-65%) for pure-tone averages at both lower and higher frequencies, and were of equal magnitude at baseline and follow-up. In contrast, environmental influences were of substantial importance (55%-88%) for rate of change of the hearing threshold over the 18-year period., Conclusions: Genetic factors are of considerable importance for level of hearing acuity, but environmental factors are more important for rate of change over an 18-year period., (© The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)