Non-identical Twins Research Articles

Challenge to the assumed rarity of heteropaternal superfecundation: findings from a case report

ABSTRACT Heteropaternal superfecundation (HP) is the fertilization, within the same cycle, of simultaneously released ova by sperm from separate males. The twin offspring resulting from HP are genetically equivalent to half-siblings, sharing an average of 25% of their genetic complement, by descent. The frequency of such twins is unknown and assumed to be rare, but is likely to be underestimated. Reasons for underestimation include inadequate detection, absence of confirmation, links between illegitimate births and dizygotic twinning, modern reproductive technologies and public unawareness of such pairs. A recently identified case of heteropaternal female twins is illustrative in this regard. HP twins pose significant implications for paternity suits, organ donation and other forensic inquiries. Recognizing the importance of this special class of non-identical twins is further emphasized, given that their inclusion in modest size twin samples might spuriously inflate estimates of genetic influence underlying measured traits.

Plantar pressures in identical and non-identical twins

Identifying environmental risk factors for musculoskeletal disorders is challenging due to the number of potential confounders. Twins are of particular interest for researchers interested in studying these types of problems due to their inherent control for the influence of genetic factors. In twin studies, this population can allow environmental risk factors to be more easily identified, and this type of study design may allow the role of biomechanics in injury and disease to be further explored. At present, it is unclear if foot function displays more similarity between certain types of twins. In this study, we hypothesized that the plantar pressures of monozygotic (identical) twins would be more similar between pairs than dizygotic (non-identical) twins. We measured static and dynamic plantar pressures from five pairs of each twin type. Statistical parametric modeling was used to compare pressure distributions at the sensor level. For >80% of stance phase, the pixel level analysis indicated that monozygotic twins had less variation in plantar pressure between pairs. The average z-statistic across the entire trial was 0.88 for the monozygotic group and 1.13 for the dizygotic group. In this study we provide evidence of greater similarity of plantar pressures in monozygotic twin pairs compared to dizygotic twins. This finding supports the use of co-twin studies investigating potentially modifiable environmental and biomechanical risk factors for musculoskeletal conditions that affect the foot and ankle.

Nature vs nurture in knee osteoarthritis – the importance of age, sex and body mass index

(1) To estimate the life-time genetic contribution for knee osteoarthritis (OA) surgery and (2) to explore any differences in the genetic contribution across age, sex and body mass index (BMI). We studied the sex-specific genetic contribution to knee OA surgery in a prospective cohort study of 62,490 twins aged 35 years or older with a follow-up period of up to 47 years (10,092 identical and 21,153 non-identical twin pairs, 54% women). To study interactions with age, we graphed the heritabilities over the lifespan for men and women. We also studied the sex-specific heritability across strata of the median BMI to explore any interactions with BMI. The overall heritability of knee OA surgery was 0.53 (95% confidence intervals [CI]=0.31-0.75), with higher heritability among women (H2=0.80 (95% CI=0.73-0.87)) than men (H2=0.39 (95% CI=0.10-0.69)). For men, the heritability started to rise after age 68. The genetic contribution was particularly low in men above median BMI (H2≥23.7kg/m2=0.08, 95% CI=-0.32-0.48). For women, the heritability was consistently high from age 50 to death, independently of BMI (H2≥22.5kg/m2=0.77, 95% CI=0.66-0.87). There is a higher and more consistent genetic contribution for knee OA surgery in women than men. In men the genetic contribution was relatively low and varied with age and BMI.

Two non-identical twins in one unit cell: characterization of 34π aromatic core-modified octaphyrins, their structural isomers and anion bound complexes.

Four different core-modified planar 34π octaphyrins (10, 11, 13, and 15) which exhibit rotational isomerism have been synthesized and characterized both in solution and solid states. Octaphyrins 10, 11 and 13 show two inseparable isomers A and B which crystallize in the same unit cell. However, 15 forms two identical isomers of A. Structurally, the two isomers in 10, 11 and 13 (A and B) are different only in the ring inversion of one of the thiophene or selenophene rings present in the terthiophene subunit of the macrocycle. In isomer A, the middle thiophene or selenophene rings are inverted, while in isomer B, the terminal thiophene rings are inverted. The 1H NMR spectrum of these macrocycles shows peaks assignable to protons of both the isomers in toluene D8. The single crystal structure analysis of 10 reveals the presence of both isomers 10A and 10B in a single unit cell with the P21/n space group. Both the isomers exhibit aromatic behaviour in the freebase form. Protonation of pyrrole nitrogens leads to exclusive formation of isomer B for 10 and 11. However, both the isomers are present upon protonation of 13 where the central heterocyclic ring of terthiophene subunits has thiophene and selenophene rings. Octaphyrin 15 crystallizes in the P21/c space group and exclusively isomer A was formed in the reaction. Protonation of pyrrole nitrogens leads to significant increases in aromaticity as revealed by 1H NMR chemical shift data. The NICS values calculated for the individual heterocyclic rings before and after protonation support such a conclusion. The AICD plots exhibit clockwise orientation of current density vectors suggesting the presence of diatropic ring current in the octaphyrins. Energy calculations at the M06L/CC-pVTZ//M06L/6-31G** level qualitatively account for exclusive stabilization of a particular isomer relative to the other upon protonation. To the best of our knowledge 10 represents the first example in expanded porphyrin chemistry where two different structural isomers crystallize in a single unit cell.

Challenging diagnosis of congenital malaria in non-endemic areas

BackgroundCongenital malaria is usually defined as the detection of asexual forms of Plasmodium spp. in a blood sample of a neonate during perinatal age if there is no possibility of postpartum infection by a mosquito bite. The incidence of congenital malaria is highly variable and seems related to several factors, such as different diagnostic methods for Plasmodium spp. detection, and area in which the epidemiologic analyses are performed. In non-endemic countries, cases of congenital malaria are rare. Hereby, a case of a congenital malaria in an HIV exposed child is reported.Case presentationA 2-month-old male child was admitted to Bambino Gesù Children’s Hospital due to anaemia and exposure to HIV. He was born prematurely in Italy by cesarean section at 34 weeks’ gestation after a bicorial, biamniotic pregnancy by a migrant woman from Nigeria. He was the first of non-identical twins. Combined with anaemia, spleen and liver enlargement was noted, malaria was hypothesized. Malaria laboratory panel was performed on the newborn, mother and other twin blood samples, as follows: (i) malaria rapid diagnostic test (RDT); (ii) Giemsa-stained thick and thin blood smears for Plasmodium spp. identification and parasitaemia titration; (iii) molecular screening and typing of Plasmodium spp. by multiplex qualitative PCR assay based on 18S rRNA gene. Genotyping of Plasmodium falciparum isolates from mother and child was performed by neutral microsatellite and highly polymorphic marker amplification.ConclusionsThe maternal RDT sample was negative, while the infant RDT was positive; in both cases microscopy of blood smears and PCR showed infection with P. falciparum. Two of the genotypic molecular markers displayed different allelic variants between the two samples. This difference could imply infection multiplicity of the mother during the pregnancy, possibly harbouring more than one isolate, only one of them being transmitted to the newborn while the other persisting in the mother’s blood. Because of the increasing number of pregnant women coming from endemic areas for malaria, an accurate anamnesis of infant’s mother, and the inclusion of Plasmodium spp. research into TORCH screenings for mother-infant pair at birth, aiming at reducing morbidity and mortality associated to the disease might be suitable.

Genetic variation in health insurance coverage.

We provide the first investigation into whether and how much genes explain having health insurance coverage or not and possible mechanisms for genetic variation. Using a twin-design that compares identical and non-identical twins from a national sample of US twins from the National Survey of Midlife Development in the United States, we find that genetic effects explain over 40% of the variation in whether a person has any health coverage versus not, and nearly 50% of the variation in whether individuals younger than 65 have private coverage versus whether they have no coverage at all. Nearly one third of the genetic variation in being uninsured versus having private coverage is explained by employment industry, self-employment status, and income, and together with education, they explain over 40% of the genetic influence. Marital status, number of children, and available measures of health status, risk preferences, and prevention effort do not appear to be important channels for genetic effects. That genes have meaningful effects on the insurance status suggests an important source of heterogeneity in insurance take up.

The effect of a sibling’s gender on earnings and family formation

We examine how the gender of a sibling affects labor market outcomes and family formation. Identification is complicated by parental preferences: if parents prefer certain sex compositions over others, children’ s gender affects not only the outcomes of other children but also the existence of potential additional children. We employ two empirical strategies that both address this problem. First, we use a large sample of singletons to estimate whether first-borns are affected by the gender of their second-born sibling. Second, we look at a sample of dizygotic (i.e. non-identical) twins. We find that a same-sex sibling increases men’s earnings and family formation outcomes (marriage and fertility), as compared to an opposite-sex sibling. The results for women are similar but the effects are smaller in magnitude and less robust. We argue that the income result for men could be driven by competition between brothers, as we find that men with brothers choose higher paying occupations. For women, we find suggestive evidence that the income premium may come partly from lower unemployment, which could be due to shared job search networks. The effects on family formation might stem from differential parental treatment for men, and from competition between sisters for women.

Genetic influences on musical specialization: a twin study on choice of instrument and music genre.

Though several studies show that genetic factors influence individual differences in musical engagement, aptitude, and achievement, no study to date has investigated whether specialization among musically active individuals in terms of choice of instrument and genre is heritable. Using a large twin cohort, we explored whether individual differences in instrument choice, instrument category, and the type of music individuals engage in can entirely be explained by the environment or are partly due to genetic influences. About 10,000 Swedish twins answered an extensive questionnaire about music-related traits, including information on the instrument and genre they played. Of those, 1259 same-sex twin pairs reported to either play an instrument or sing. We calculated the odds ratios (ORs) for concordance in music choices (if both twins played) comparing identical and nonidentical twin pairs, with significant ORs indicating that identical twins are more likely to engage in the same type of music-related behavior than are nonidentical twins. The results showed that for almost all music-related variables, the odds were significantly higher for identical twins to play the same musical instrument or music genre, suggesting significant genetic influences on such music specialization. Possible interpretations and implications of the findings are discussed.

Familial nonsyndromic hearing loss with incomplete partition type II caused by novel DSPP gene mutations

Background: Familial nonsyndromic hearing loss (NSHL) with incomplete partition type II (IP-II) is a very rare condition.Aims/Objectives: To determine the audiological feature, inheritance patterns and genetic etiology of familial NSHL with IP-II in a Chinese family with eight family members.Material and methods: Clinical data were collected from all eight family members, selected deafness genes were sequenced in proband and whole genome sequencing of seven family members was performed.Results: The proband were a pair of male nonidentical twins (III:1, III:2). Three patients in this family, including the twins and their father (II:1), were diagnosed with bilateral NSHL with IP-II, and no mutation was found in the genes of SLC26A4, GJB2, GJB3, mitochondrial 12S rRNA, and MITF. Whole genome sequencing data indicated de novo mutations of the gene DSPP, c.3085A > G and c.3087C > T, which resulted in p.N1029D and co-segregated with deafness phenotype, were the underlying genetic etiology.Conclusion and significance: Familial NSHL with IP-II is extremely rare. In this family, de novo DSPP gene mutations, were considered to be the most probable genetic etiology. And this is the first report to reveal DSPP gene mutations leading to familial NSHL with IP-II.

Molecular Consortia-Various Structural and Synthetic Concepts for More Effective Therapeutics Synthesis.

The design and discovery of novel drug candidates are the initial and most probably the crucial steps in the drug development process. One of the tasks of medicinal chemistry is to produce new molecules that have a desired biological effect. However, even today the search for new pharmaceuticals is a very complicated process that is hard to rationalize. Literature provides many scientific reports on future prospects of design of potentially useful drugs. Many trends have been proposed for the design of new drugs containing different structures (dimers, heterodimers, heteromers, adducts, associates, complexes, biooligomers, dendrimers, dual-, bivalent-, multifunction drugs and codrugs, identical or non-identical twin drugs, mixed or combo drugs, supramolecular particles and various nanoindividuals. Recently much attention has been paid to different strategies of molecular hybridization. In this paper, various molecular combinations were described e.g., drug–drug or drug-non-drug combinations which are expressed in a schematic multi-factor form called a molecular matrix, consisting of four factors: association mode, connection method, and the number of elements and linkers. One of the most popular trends is to create small–small molecule combinations such as different hybrids, codrugs, drug–drug conjugates (DDCs) and small-large molecule combinations such as antibody-drug conjugates (ADCs), polymer-drug conjugates (PDCs) or different prodrugs and macromolecular therapeutics. A review of the structural possibilities of active framework combinations indicates that a wide range of potentially effective novel-type compounds can be formed. What is particularly important is that new therapeutics can be obtained in fast, efficient, and selective methods using current trends in chemical synthesis and the design of drugs such as the “Lego” concept or rational green approach.

Decoding of tyrosinase leads to albinism in a nonidentical twin

Oculocutaneous albinism (OCA) is an autosomal recessive disorder, phenotypically subcategorized as OCA subtype 1A (OCA-1A) and OCA subtype 1B (OCA-1B). Both the subtypes are genetically caused by the mutations in the tyrosinase (TYR) gene. A 6-month-old nonidentical twin sister was albino who was diagnosed with OCA-1A and had clinical features including hypopigmentation in iris, lid, lashes, skin, nystagmus, and albinotic fundus. Genetic screening revealed the pathogenic mutation at TYR gene locus in albino child, whereas the other child was carrier and holding normal phenotype. We report a differential TYR expression pattern on one of the nonidentical twins.

A Unique Bond: Twin Bereavement and Lifespan Associations of Identical and Fraternal Twins

Empirical analyses of twin mortality often use models with dependent unobserved frailty terms capturing genetic and childhood environmental determinants. This ignores that mortality rates can be co-dependent due to bereavement effects, i.e. to a time-dependent causal effect of the loss of the co-twin on the mortality rate of the surviving twin. We develop a novel methodology and perform an empirical analysis based on a comprehensive model incorporating both types of dependence. We prove full identification without functional-form restrictions and we estimate models with data on twin pairs from the Danish Twin Registry. Among men, the loss of an identical co-twin at age 75 causally reduces the remaining lifetime on average by more than a year. This bereavement effect is less severe among non-identical twins or if the loss occurs at a higher age. Estimates of correlations between the frailty terms by zygosity and the ensuing implications for the relative importance of mortality determinants are highly sensitive to whether bereavement is taken into account.

Heritability and correlation of lip print, palm print, fingerprint pattern and blood group in twin population.

Background:Twins are similar in many ways owing to the genetical and environmental factors. However, still, there are certain things that are not similar among them, and this is the challenge for personal identification among the twins.Objectives:Our present study aimed to know and assess the similarities and differences present between the monozygotic (identical) and dizygotic (fraternal) twins in relation to lip prints, palm prints, fingerprints and blood group and to evaluate their heritability among parents and their offspring.Materials and Methods:The study group comprised 30 twins and their parents – 15 identical and 15 nonidentical twins. The age of twins ranged from 15 years to 40 years. Lip print, palm print, fingerprint and blood group were statistically analyzed.Results:All the data were subjected to statistical analysis. The identical twins showed more percentage of similarities in comparison to the non identical twins. The inheritance pattern was significant for twins in case of their lip prints while palm prints and finger prints showed no such significance in inheritance pattern whereas there was significant association seen in case of blood groups of identical twins and their parents.Conclusion:Lip prints, palm prints, fingerprints and blood groups are the important parameters in forensic science for individual identification. Many studies have been done till now in individual but very few studies done in twin population. To the best of knowledge, ours is the first study of its kind with multiple parameters and its heritability in twins. We have observed that heritability in twins with relation to lip print was statistically significant and all the parameters can be used independently to identify the twins.

Mullerian Agenesis in One of the Non-Identical Twins: A Case Report and Literature Review

Mullerin agenesis also referred as mullerian aplasia, Mayer-Rokitansky-Kuster-Hauser Syndrome (MRKH) or vaginal agenesis is the congenital anomaly of vertical fusion defect of mullerian system resulting in variable abnormalities of female reproductive tract with normal functioning ovaries. It is second most common cause of primary amenorrhea after gonadal agenesis. The occurrence of mullerian agenesis in twins is very rare. We present the case of one of the non-identical twins, 22 years female, with primary amenorrhea. Her elder twin sister had a normal female reproductive system. In our case, diagnosis was supported by presence of definitive primary amenorrhea with well-developed secondary sexual characteristics. Normal physiological hormonal levels ruled out the ovarian or pituitary pathology. Imaging studies like ultrasonography and magnetic resonance imaging (MRI) provided additional confirmation.

Facial Trustworthiness is Associated with Heritable Aspects of Face Shape

Facial trustworthiness is thought to underlie social judgements in face perception, though it is unclear whether trustworthiness judgements are based on stable facial attributes. If this were the case, we could expect a genetic component of facial trustworthiness. From facial photographs of a large sample of identical and nonidentical twins and siblings (1320 individuals), we tested for genetic variation in facial trustworthiness and genetic covariation with several stable facial attributes, including facial attractiveness, two measures of masculinity, and facial width-to-height ratio. We found a significant genetic component of facial trustworthiness in men (but not women), and significant genetic correlations with the stable morphological facial traits of attractiveness (positive), perceived masculinity (negative), and facial width-to-height ratio (negative). However, there was no significant genetic or shared environmental correlation between facial trustworthiness and an objective masculinity score based on facial landmark coordinates, despite there being a significant phenotypic correlation. Our results suggest that heritable facial traits influence trustworthiness judgements.

The Path to New Therapies for Schizophrenia and Bipolar Illness

Schizophrenia and bipolar illness are two of the most serious forms of mental illness. Until relatively recently, almost nothing was known about the molecular pathogenesis of either illness. The single largest risk factor that predisposes people to schizophrenia or bipolar illness is genetic risk. Heritability is high, and the incidence is significantly higher in identical twins than in nonidentical twins. Despite decades of work aimed at identifying the genes involved in these two illnesses, virtually no progress had been made until the past decade. With the knowledge and technologies that have been gained from the Human Genome Project, it has been possible to begin to understand the underlying genetics and to use the new information to begin the effort to discover new and better medicines to treat these illnesses. This article will describe the past decade of work toward this goal and articulate both the promise that now exists and what is still needed to bring dramatic and tangible change to patients.-Scolnick, E. M. The path to new therapies for schizophrenia and bipolar illness.

The Non-Identical Twins in UK Public Law: Reasonableness and Proportionality

Ever since the Wednesbury decision in 1947 (Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948] 1 KB 223) courts and public law scholars in the United Kingdom (UK) have been struggling to comprehend the meaning of ‘reasonableness’ and its relation to ‘proportionality’. The main purpose of this article is to promote conceptual clarity in UK public law by describing the nature of reasonableness and proportionality as grounds of judicial review and by highlighting the overlooked similarities and differences between them.The main arguments of this article are that: (i) reasonableness is, in essence, an exercise in balancing and weighing; (ii) proportionality adds very little to the existing grounds of judicial review in UK public law; (iii) this addition is not necessarily focused on the administrative weighing and balancing process; and (iv) since proportionality adds very little to the existing grounds of judicial review, there is no conceptual or normative reason to prevent having proportionality as a general ground of judicial review in UK public law.

Just War Theory and the Laws of War as Nonidentical Twins

AbstractThis essay examines the similarities, but even more the dissimilarities, between (nonrevisionist) just war theory and the laws of war. The similarities are obvious: both just war theory and the laws of war distinguish jus ad bellum from jus in bello, and incorporate the principles of distinction, proportionality, and necessity. The dissimilarities derive from the special character of law. Law needs binary, yes-no standards for drawing lines, for example between armed conflict and lesser forms of violence. Laws come in packages (regimes), so that changing only one law is not always practicable. And legal propositions, unlike philosophical propositions, are often detachable from their reasons and applied in unexpected and unwelcome ways. This is especially important in the stresses of battle, when rules of warfare must be usable “off the shelf” by middle- or lower-ranked personnel with no opportunity for bespoke deliberation. The essay provides contemporary illustrations of these differences.

The vicissitudes of triangulation in the lives of twins: a Kleinian perspective on an infant observation

This article is an account of an infant observation of non-identical twins whose early development was characterised by the shadow of the postnatal depression their mother suffered after the birth of her first child. Using extracts from the observations, the vicissitudes of triangulations are explored drawing on a Kleinian theoretical perspective. The author considers the twin’s individual internal responses to the changes in their external environment and in particular in relation to the experience of weaning and the developing presence of the absent object. The task and the role of the observer are briefly explored.

Risk Factors and Relationship of Cutaneous and Uveal Melanocytic Lesions in Monozygotic and Dizygotic Twin Pairs.

BackgroundThe similar genetic background of a pair of twins, and the similar environmental impacts to which they are exposed allow an exact and objective investigation of various constitutional and environmental factors in naevus development. As far as we are aware, this is the first published survey that simultaneously examines cutaneous and ocular pigmented lesions in an appreciable sample of identical and non-identical twins.Methods172 pairs of twins of Caucasian origin were included in this study. A whole-body skin examination and a detailed ophthalmological examination were performed to determine the density of melanocytic lesions. A standardized questionnaire was used to assess the data relating to constitutional, sun exposure and other variables.ResultsA notably high proportion of the subjects (36.78%) manifested one or more clinically atypical melanocytic naevi (CAMNs), and approximately one-third (31.4%) of them at least one benign uveal pigmented lesion (BUPL). The incidence of iris freckles (IFs), iris naevi (INs) and choroidal naevi (CHNs) proved to be 25.35%, 5.98% and 3.52%, respectively. The interclass correlation coefficients for common melanocytic naevi (CMNs), CAMNs, and INs were 0.77, 0.76 and 0.86 in monozygotic twins, as compared with 0.5, 0.27 and 0.25 in dizygotic twin pairs, respectively. A statistically significant correlation was found between the prevalence of CAMNs and that of INs.ConclusionsThis significant correlation suggests the existence of a subgroup of Caucasian people with an increased susceptibility to both cutaneous and ocular naevus formation. There is accumulating evidence that, besides the presence of cutaneous atypical naevi, INs can serve as a marker of a predisposed phenotype at risk of uveal melanoma. The correlation between cutaneous and ocular pigmented lesions underlines the need for the adequate ophthalmological screening of subjects with CAMNs and INs.