Twin pairs

Type of twin pair Number of pairs Intraclass R... 

Mania, manic-depression and depression, which comprise the affective disorders, are relatively common it has been estimated that there is an incidence of at least 2% in most societies throughout the world. There is good evidence to suggest that genetic factors play a considerable role in predisposing a patient to an affective disorder. In a seminal Danish twin register study, in which the incidence of affective disorders was determined in all twins of the same sex born in Denmark between 1870 and 1920, a total of 110 pairs of twins were identified in which one or both had manic-depression. The concordance rates, that is the rate of coexistence of the disorder in twin pairs, for all types of affective disorder were found to be... 

Chapter 2, Fig. 1. An [ F]FDG-PET scan depicting glucose metabolism in a monozygotic twin pair and in a control subject. Note the clear reduction in [ F]FDG uptake especially in temporoparietal areas (thick arrows) in the cotwin having AD (on the left), and similar, but less pronounced reduction in same brain areas (thin arrows) in the cognitively healthy cotwin (in the middle) as compared with the uptake in a control subject (on the right). 

McNeil, T.F., Cantor-Graae, E., and Weinberger, D.R. (2000) Relationship of obstetric complications and differences in size of brain structures in monozygotic twin pairs discordant for schizophrenia. Am J Psychiatry 157 203-212. 

Tourette s Syndrome is a familial disorder (Pauls et ah, 1991 Walkup et ah, 1996). Twin and family studies provide evidence that genetic factors are involved in the vertical transmission within families of a vulnerability to TS and related disorders. The concordance rate for TS among monozygotic twin pairs is 50% while the concordance of dizygotic twin pairs is about 10% (Price et ah, 1985). If co-twins with chronic motor tic... 

TABLE 10-1. Concordance (+) and discordance (-) of mood disorder in twin pairs... 

In genetics, similarity in a twin pair with respect to the presence or absence of a disease or trait. 

Note also that, when a contribution due to a uniaxial magnetic anisotropy is included in the particle energy [see Eq. (4.73)], the emerging parameter h, on changing, in a natural way guides the system through the variety of oscillation situations from the absence of any symmetric potential (an isotropic particle) to a twin pair of infinitely deep wells (a magnetically hard particle). In still other... 

Poulsen P, Vaag AA, Kyvik KO, Moller Jensen D, Beck-Nielsen H (1997) Low birth weight is associated with NIDDM in discordant monozygotic and dizygotic twin pairs. Diabetologia, 40 439-446. 

Fibrinogen is a composite of six protein chains, containing twin pairs of three different proteins. Electron microscopy has shown that fibrinogen is a rod-shaped molecule, with two round bumps on each end of the rod and a single round bump in the middle. So fibrinogen resembles a set of barbells with an extra set of weights in the middle of the bar. 

In a large population-based twin study [69], it was shown that in Italy 75% of monozygotic twin pairs were concordant for CD compared with only 11% of dizygotic twin pairs. From these results, it was concluded that environmental... 

Deficits in attention and motor skills persisted after 1 year of abstinence from stimulant abuse in 50 twin pairs in which only one member had heavy stimulant abuse with cocaine and/or amphetamines (55). Stimulant abusers performed significantly worse on tests of motor skills and attention, and significantly better on one test of visual vigilance. These findings provide evidence of long-term residual effects of stimulant abuse. 

In a crossover study among 581 twin pairs aged between 14 months and 6 years only 0.5-4% had adverse reactions to MMR vaccine. The difference between the reaction rate reported in the immunized members of the twin pairs and those reported in the placebo-injected twin sisters or brothers showed that most of the reactions were temporally and not causally related to immunization. Respiratory symptoms, nausea, and vomiting were more frequent in the placebo-injected group than in the MMR-immunized group (9). 

Kates WR, Burnette CP, Eliez S, et al. Neuroanatomic variation in monozygotic twin pairs discordant for the narrow phenotype for autism. Am J Psychiatry2004 161(3) 539 46. 

Figure 2. Schematic representation of the cyclic reduction/oxidation of twin pairs of MoOe octahedra between the comer and the edge-sharing arrangements (Boxes represent MoOe octahedra with sharing of oxygen atoms at comers for M0O3 or edges for M0O2). The figure is not completely accurate, because it cannot take into account the fact that the arrangements are not perpendicular to the main axes of the lattice.

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