Monozygotic twins discordant for phacomatosis pigmentovascularis: evidence for the concept of twin spotting.

The term phacomatosis pigmentovascularis (PPV) refers to the occurrence of vascular nevi with melanocytic or epidermal nevi. We report on monozygotic twins (MZTs) discordant for phacomatosis cesioflammea (PPV type II) providing evidence for the mechanism of twin spotting in the development of PPV. The affected twin had a nevus flammeus on the right arm and the right maxilla, and a pigmented area on the trunk in keeping with a persistent, aberrant Mongolian spot. The affected twin had bilateral ocular melanocytosis with abnormal scleral pigmentation, iris mamillations, increased pigmentation of the trabecular meshwork, and increased fundal pigmentation and secondary glaucoma. DNA testing confirmed monozygosity. This case of MZTs discordant for PPV supports the hypothesis that PPV results from mosaicism due to a post-zygotic mutational event and the concept of twin spotting.

Longitudinal study of interpersonal dependency in female twins

Interpersonal dependence is thought to be important in a number of physical and psychological disorders. There are several developmental theories that suggest environmental influences in childhood are important.

Emotions and Power: Reconciling Conceptual Twins

While the existence of an ‘emotional turn’ within the social sciences is now widely acknowledged, some areas have garnered less specific attention than others. Perhaps the most significant absence within this literature is an explicit exploration of the relationship between emotions and relations of power and domination. This article will attempt such an endeavour. In doing so, I will draw on some key work from within the sociology of emotions, such as Barbalet, Collins, Kemper and Turner, and from the power literature within social theory more generally, including Dahl, Elias, Foucault, Giddens, Gramsci and Lukes. The main thrust of the argument is that power and emotion are conceptual twins in need of a serious theoretical reunion, and that emotions have played a largely unacknowledged, ‘under-labouring’ role within most theories of power. The need for a more unified approach to these two concepts is highlighted.

Stress and coping in parents of newly born twins

Objective: Research indicates that parents of twins have poorer psychosocial outcomes than parents of singletons. Parents who have conceived using assisted reproductive technology (ART) have been found to be at higher risk of negative psychosocial outcomes compared to parents who have conceived spontaneously. The current study aimed to model the factors associated with parenting stress of newly-born twins, using the Transactional Model of Stress.

Methods: Data were collected using a cross-sectional survey design with participants identified from delivery records across Northern Ireland. Mothers and fathers (n = 104) of twins aged between 1 and 12 months old returned a questionnaire pack containing the Parenting Stress Index, Impact on the Family Scale-Financial Burden, Coping Orientation to Problems Experienced – Brief Version, Multidimensional Scale of Perceived Social Support, General Health Questionnaire and a demographic questionnaire.

Results: There were no differences on psychological outcomes between parents who had conceived via ART and those who conceived spontaneously. Regression analyses found that social interaction and support is an important variable in terms of the psychological outcomes experienced by parents of twins.

Conclusion: Parents of newly-born twins regardless of the mode of conception should be considered an at risk group for parental distress. Support groups such as the Twins and Multiple Births Association could be important in providing that crucial social interaction and support that seems to be important in the emotional well-being of parents of twins.

Gene-environment interactions and aging visual function: a classical twin study.

OBJECTIVE:
To elucidate the contribution of environmental versus genetic factors to the significant losses in visual function associated with normal aging.
DESIGN:
A classical twin study.
PARTICIPANTS:
Forty-two twin pairs (21 monozygotic and 21 dizygotic; age 57-75 years) with normal visual acuity recruited through the Australian Twin Registry.
METHODS:
Cone function was evaluated by establishing absolute cone contrast thresholds to flicker (4 and 14 Hz) and isoluminant red and blue colors under steady state adaptation. Adaptation dynamics were determined for both cones and rods. Bootstrap resampling was used to return robust intrapair correlations for each parameter.
MAIN OUTCOME MEASURES:
Psychophysical thresholds and adaptational time constants.
RESULTS:
The intrapair correlations for all color and flicker thresholds, as well as cone absolute threshold, were significantly higher in monozygotic compared with dizygotic twin pairs (P<0.05). Rod absolute thresholds (P = 0.28) and rod and cone recovery rate (P = 0.83; P = 0.79, respectively) did not show significant differences between monozygotic and dizygotic twins in their intrapair correlations, indicating that steady-state cone thresholds and flicker thresholds have a marked genetic contribution, in contrast with rod thresholds and adaptive processes, which are influenced more by environmental factors over a lifetime.
CONCLUSIONS:
Genes and the environment contribute differently to important neuronal processes in the retina and the role they may play in the decline in visual function as we age. Consequently, retinal structures involved in rod thresholds and adaptive processes may be responsive to appropriate environmental manipulation. Because the functions tested are commonly impaired in the early stages of age-related macular degeneration, which is known to have a multifactorial etiology, this study supports the view that pathogenic pathways early in the disease may be altered by appropriate environmental intervention.

The genetics of coronary heart disease: The contribution of twin studies

Despite the decline in coronary heart disease in many European countries, the disease remains an enormous public health problem. Although we know a great deal about environmental risk factors for coronary heart disease, a heritable component was recognized a long time ago. The earliest and best known examples of how our genetic constitution may determine cardiovascular risk relate to lipoprotein(a), familial hypercholesterolaemia and apolipoprotein E. In the past 20 years a fair number of polymorphisms assessed singly have shown strong associations with the disease but most are subject to poor repeatability. Twins constitute a compelling natural experiment to establish the genetic contribution to coronary heart disease and its risk factors. GenomEUtwin, a recently funded Framework 5 Programme of the European Community, affords the opportunity of comparing the heritability of risk factors in different European Twin Registries. As an illustration we present the heritabilities of systolic and diastolic blood pressure, based on data from over 4000 twin pairs from six different European countries and Australia. Heritabilities for systolic blood pressure are between 52 and 66% and for diastolic blood pressure between 44 and 66%. There is no evidence of sex differences in heritability estimates and very little to no evidence for a significant contribution of shared family environment. A non-twin based prospective case/cohort study of coronary heart disease and stroke (MORGAM) will allow hypotheses relating to cardiovascular disease, generated in the twin cohorts, to be tested prospectively in adult populations. Twin studies have also contributed to our understanding of the life course hypothesis, and GenomEUtwin has the potential to add to this.

Somatic point mutations in mtDNA control region are influenced by genetic background and associated with healthy aging: a GEHA stud

Tissue specific somatic mutations occurring in the mtDNA control region have been proposed to provide a survival advantage. Data on twins and on relatives of long-lived subjects suggested that the occurrence/accumulation of these mutations may be genetically influenced. To further investigate control region somatic heteroplasmy in the elderly, we analyzed the segment surrounding the nt 150 position (previously reported as specific of Leukocytes) in various types of leukocytes obtained from 195 ultra-nonagenarians sib-pairs of Italian or Finnish origin collected in the frame of the GEHA Project. We found a significant correlation of the mtDNA control region heteroplasmy between sibs, confirming a genetic influence on this phenomenon. Furthermore, many subjects showed heteroplasmy due to mutations different from the C150T transition. In these cases heteroplasmy was correlated within sibpairs in Finnish and northern Italian samples, but not in southern Italians. This suggested that the genetic contribution to control region mutations may be population specific. Finally, we observed a possible correlation between heteroplasmy and Hand Grip strength, one of the best markers of physical performance and of mortality risk in the elderly. Our study provides new evidence on the relevance of mtDNA somatic mutations in aging and longevity and confirms that the occurrence of specific point mutations in the mtDNA control region may represent a strategy for the age-related remodelling of organismal functions.

Alternative Factor Models and Heritability of the Short Leyton Obsessional Inventory-Children's Version

An alternative models framework was used to test three confirmatory factor analytic models for the Short Leyton Obsessional Inventory-Children's Version (Short LOI-CV) in a general population sample of 517 young adolescent twins (11-16 years). A one-factor model as implicit in current classification systems of Obsessive-Compulsive Disorder (OCD), a two-factor obsessions and compulsions model, and a multidimensional model corresponding to the three proposed subscales of the Short LOI-CV (labelled Obsessions/Incompleteness, Numbers/Luck and Cleanliness) were considered. The three-factor model was the only model to provide an adequate explanation of the data. Twin analyses suggested significant quantitative sex differences in heritability for both the Obsessions/Incompleteness and Numbers/Luck dimensions with these being significantly heritable in males only (heritability of 60% and 65% respectively). The correlation between the additive genetic effects for these two dimensions in males was 0.95 suggesting they largely share the same genetic risk factors.

Outcome of pregnancy following renal transplantation

Successful renal transplantation improves fertility with 1 in 50 women of childbearing age becoming pregnant. Pregnancy following renal transplantation is associated with increased maternal and fetal complications. In Belfast 118 women of childbearing age (15-45 yrs) have received a renal allograft and of these 14 (12%) have become pregnant. Twenty-seven pregnancies have resulted in 23 live births (including one set of identical twins), 1 still birth and 4 first trimester abortions. The most frequent complications were hypertension and prematurity. In this group of patients, whose sole immunosuppressive therapy was azathioprine and prednisolone, pregnancy post transplantation was associated with frequent successful outcome and a low incidence of maternal and fetal complications.

Michael Allen: Close Readings: Essays on Irish Poetry

The late Michael Allen was a member of the famous Belfast Group, and one of the most authoritative critical voices on poetry from Northern Ireland, intimately part of the North’s poetic movement since the early 1960s. He taught at Queen’s University, where he was a colleague of Seamus Heaney and tutor to poets such as Paul Muldoon and Medbh McGuckian. Seamus Heaney called him ‘the reader over my shoulder’. Close Readings brings together interlinked critical writings which have crucially influenced approaches to Irish poetry during the last forty years. The book ends with an extended essay, hitherto unpublished: ‘Doubles, Twins and the Feminine: Development in the Poetry of Michael Longley’.

Close Readings contains a Foreword by Fran Brearton, which relates Michael Allen’s essays to continuing critical and cultural debates. Edna Longley’s Afterword offers a personal view of Allen’s involvement with poetry in Belfast.

Management of newly diagnosed chronic myeloid leukaemia during a twin pregnancy using leucapheresis: Case report and review of the literature

A case of chronic myeloid leukaemia diagnosed as an incidental finding in a 32-year-old woman, pregnant with twins at 11 weeks gestation, is presented. Management of the patient was with leucapheresis and supportive care until spontaneous delivery of two morphologically normal infants (one male, one female) at 37 weeks gestation. Special considerations while employing leucapheresis in pregnant patients are discussed.