OBJECTIVE The etiology of chronic fatigue syndrome is unknown, but genetic influences may be important in its expression. Our objective was to assess the role of genetic and environmental factors in unexplained chronic fatigue. METHODS A classic twin study was conducted using 146 female-female twin pairs, of whom at least one member reported > or =6 months of fatigue. After completing questio...

Introduction: Twin pregnancy is associated with more pregnancy complications and poorer pregnancy outcome than singleton pregnancy. Aim: To evaluate the maternal and fetal complications in twin pregnancies. Materials and methods: 300 Twin Pregnancies were studied over a period of 16 months from 200607 to evaluate complications to the mother and both fetuses. Data obtained at the time of deliver...

Skin colour has been measured by reflectance spectrophotometry on 134 pairs of twins at three sites, forehead, forearm and upper arm, each at three wavelengths, 425, 545 and 685 nm. Tanning is measured most reliably at 685 nm and at this wavelength the heritability is high at the least exposed upper arm site, intermediate on the forearm, while on the forehead variation is entirely environmental...

OBJECTIVES To investigate the cause of sporadic motor neuron disease (MND) by twin study, so allowing (1) estimation of the genetic contribution, and (2) collection of matched pairs for a case-control study of possible environmental factors. METHODS 10872 death certificates bearing the diagnosis MND were collected from 1979 to 1989 inclusive. Inspection of individual birth entries allowed ide...

Background. In subjects of all ages, those who weigh the most often have the highest blood pressure. Thus, in epidemiological studies, weight is the most important correlate of blood pressure. Using the data from the Medical College of Virginia Twin Study, we asked these questions: 1) Do the same genetic paths that regulate body size also regulate systolic and diastolic blood pressure? 2) Are t...

Proponents of the validity of the classical MZ-DZ twin comparison model for calculating heritability claim that the environments influencing MZ and DZ twin individuals are essentially identical. This 'equal environments assumption' may or may not be universally true when applied to the analysis of subjective traits. We examined the validity of this assumption as applied to the propensity for sm...

BACKGROUND Perfectionism may be a premorbid risk factor for eating disorders. Evidence of familial transmission suggests features of perfectionism may be genetically determined. This study examines the structure of perfectionism using classical twin design models. METHODS Independent (IP) and common (CP) pathway models are used to investigate the extent to which genetic and environmental fact...

The primary objectives of the present study are to introduce the Colorado Longitudinal Twin Study of Reading Disability, the first longitudinal twin study in which subjects have been specifically selected for having a history of reading difficulties, and to present some initial assessments of the stability of reading performance and cognitive abilities in this sample. Preliminary examination of...

The study explored the genetic susceptibility and prevalence of epilepsy in twins. The data on epilepsy were retrieved from the health records of 199 pairs of twins. Proband concordance rate in monozygotic (MZ) twins was four times more than that in dizygotic (DZ) twins (0.67 vs. 0.17). Three of 15 (20%) affected twin kinships had epileptic first-degree relatives. These findings indicated signi...

Blood alcohol measurements were obtained for 206 pairs o f twins who had ingested a standard dose of alcohol (0.75g/kg body weight) and repeat measurements were obtained for 40 of these pairs on a second occasion. The repeatability o f the peak blood alcohot concentration (BAC) was 0.66, that o f the rate of elimination was 0.39, and that o f the time to peak BAC was 0.27. Only a small portion ...