Ethics roundtable debate: Child with severe brain damage and an underlying brain tumour

A young person presents with a highly malignant brain tumour with hemiparesis and limited prognosis after resection. She then suffers an iatrogenic cardiac and respiratory arrest that results in profound anoxic encephalopathy. A difference in opinion between the treatment team and the parent is based on a question of futile therapy. Opinions from five intensivists from around the world explore the differences in ethical and legal issues. A Physician-ethicist comments on the various approaches.     

Level of family dysfunction and genetic influences on smoking in women

BACKGROUND: An adoption study of alcoholism suggests that in women, the impact of genetic risk factors become greater in the presence of conflict in the family of origin. Is the same true for cigarette smoking (CS)? METHOD: We obtained, in a sample of 1676 twins from female female twin pairs from a population-based register, a measure of maximum lifetime CS (divided into six ordinal categories) and family dysfunction (FD) assessed as the mean report of up to four informants (twin, co-twin, mother, father). Statistical analysis was conducted by traditional regression analysis and a moderator structural equation twin model using the computer program Mx. RESULTS: With increasing levels of FD, maximum CS increased substantially while correlations for CS in monozygotic (MZ) and dizygotic (DZ) twins decreased modestly. Regression analyses demonstrated reduced twin-pair resemblance for CS with increasing levels of FD. The best-fit structural equation model found high levels of heritability for CS and no evidence for a role of shared environment. With increasing levels of FD, the proportion of variance in CS due to genetic factors (i.e. heritability) decreased while that due to unique environmental effects increased. CONCLUSIONS: Several different statistical methods suggested that, contrary to prediction, heritability of CS decreased rather than increased with higher levels of dysfunction in the family of origin. The hypothesis that genetic effects for psychiatric and drug-use disorders become stronger in more adverse environments is not universally true.     

Evaluation of genetic substructure in the Irish Study of High-Density Schizophrenia Families

The presence of genetic substructure has the potential to diminish the chances of detecting a linkage signal. Using a Markov chain Monte Carlo procedure developed by Pritchard and colleagues and implemented in the program STRUCTURE, we evaluated the evidence for genetic substructure using genotypes from 37 microsatellite markers in affected individuals selected at random from 263 multiplex families in the Irish Study of High-Density Schizophrenia Families. We found no evidence for the presence of genetic substructure in this sample.     

An investigation of the predictors of bone mineral density and response to therapy with alendronate in osteoporotic men

Male osteoporosis is an important disease, with 25-30% of all hip fractures occurring in men. In a recent randomized, placebo-controlled study of osteoporotic males, alendronate 10 mg daily for 2 yr led to significant increments in bone mineral density (BMD), of a similar magnitude to those observed in postmenopausal women. In this study, specimens collected at intervals during the recent trial of alendronate in male osteoporosis, from 197 of the original 241 participants, were assayed for testosterone, estradiol, IGF-I, IGF binding protein 3 (IGFBP-3), bone-specific alkaline phosphatase [BSAP (serum)], and N-telopeptide of type I collagen corrected for creatinine [NTx (urine)]. Together with fracture and densitometry data from the original study, relationships were examined between BMD and serum IGF-I, IGFBP-3, testosterone, estradiol, BSAP, and urine NTx, both at baseline and during treatment with alendronate, to gain possible insights into the pathogenesis of male osteoporosis. Statistically significant (P 相似文献   

Influence of ascertainment strategy on finding sex differences in genetic estimates from twin studies of alcoholism

Twin studies have yielded contradictory findings about sex differences in genetic influences on the etiology of alcoholism. Studies based on population registers or epidemiological samples have yielded similar estimates of heritability (50-60% of the total variance) for males and females. In contrast, studies of twins identified through treatment settings have found sizeable genetic contributions to alcoholism in males but usually negligible heritabilities for females. We investigated this discrepancy by applying a "simulated" treatment ascertainment strategy to data on alcohol-related disorders collected by structured interviews with a population-based sample of adult twins aged 18-56 years from the Mid-Atlantic Twin Registry. Structural models were used to estimate heritabilities for two definitions of treatment, and these estimates were compared with those obtained from the population-based sample. In males, heritability estimates were similar across sampling methods, but the treatment ascertainment methods yielded higher estimates of common environmental influences. For females, heritability estimates based on a broad definition of treatment were similar to those obtained by using the random ascertainment design. However, estimates based on sampling women who had been in alcohol-treatment programs were (nonsignificantly) lower than those obtained with the other methods. These results provide partial support for the hypothesis that differences in sampling method may account for differences in heritability estimates for alcoholism among studies of female twins. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:754-761, 2000.     

Parent, child, and social correlates of parental discipline style: a retrospective, multi-informant investigation with female twins

Background: The type of parental discipline used in families appears to be related to parental characteristics, child temperament, and aspects of the social context. Within these three areas, we examine specific correlates of parental discipline (namely, limit setting and physical discipline) using a multiple informant model. Method: Using interview data from 2003 female twins from a population-based twin registry and 1472 of their parents, we examined retrospective reports of parental discipline from three perspectives. First, father and mother reporting separately on the type of discipline they provided for their offspring; second, each twin reporting on the type of discipline they received from their parents; and third, each parent reporting on the discipline provided by their spouse. Using a mixed model regression, we examined the impact on parental discipline of 25 potential predictor variables, as reported by parents, from three domains: social context, parental factors, and childhood vulnerability factors. Results: There was a great deal of overlap between the independent variables for the two types of discipline in the areas of child vulnerability factors and family relationships, with similar effect sizes for child disobedience, teenage rebelliousness, and family discord. However, the profiles of parental characteristics associated with each type of discipline were quite different. Greater use of physical discipline was associated with less parental warmth, a higher incidence of parental lifetime generalised anxiety disorder, and more frequent religious attendance. Greater use of limit setting was associated with more years of parental education, younger age, and greater parental extroversion and authoritarianism. Conclusions: Parental characteristics, child temperament, and social context may all contribute to the frequency of discipline used in families, but parental characteristics may be most influential in determining the type of discipline used. Accepted: 8 January 2001