摘要:

AbstractEnvironmental factors are etiologically important in many non‐Mendelian familial disorders in man. Because such disorders often occur as “sporadic” cases, (ie, an affected individual with no affected relatives), it is tempting to assume that such cases represent an “environmental” form of the disorder. This paper presents an evaluation of the sensitivity, specificity, and positive and negative predictive power (PPV and NPV) of this “sporadic vs familial classification.” The model assumes etiologic heterogeneity with a subpopulation of cases due to a “major” environmental event acting independent of genotype and the remaining cases resulting from a generalized single major locus (SML). Sibship size is modeled by a truncated negative binomial distribution. For rare disorders, this classification has high sensitivity and NPV but low specificity and PPV. As the disorder becomes more common, sensitivity and NPV fall while specificity and PPV rise. The power of the method increases substantially with increasing sibship size up to four or five, but further increases in power are minimal. MZ twins add considerable power to the method but aunts and uncles add little if anything. Both a correlational (phi) and an agreement‐based (kappa) statistic indicate that, under most realistic circumstances, the relationship between etiology and famil

ISSN:0741-0395    

DOI:10.1002/gepi.1370040502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractEpidemiological studies have consistently found women to be at greater risk than men for affective disorders. This sex effect may help clarify genetic transmission and heterogeneity. Data from eight family studies of unipolar and eight family studies of bipolar probands were used to calculate family resemblance sex ratios. These observed sex ratios were then compared to sex ratios predicted by X‐linked and nonfamilial effects models. Maximum likelihood estimation of competing models revealed that X linkage was not a good fit to the unipolar data. The bipolar studies were not consistent with either the X‐linked or the nonfamilial effects mo

ISSN:0741-0395    

DOI:10.1002/gepi.1370040503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA multivariate path model of genetic and environmental transmission, used to derive expected covariances among adult twin and sibling pairs and their parents, was fitted to fear factor data from 250 twin families and 91 sibling families, with the use of a maximum‐likelihood estimation procedure. The full model, with 259 free parameters, provides for parental cultural transmission, common twin and sibling environment, genotype‐environment correlation, direct assortative mating, and genetic and environmental correlations. Significant effects were indicated for heritable transmission of common fears and phobias, and a single genetic factor accounted for most of the genetic covariance among the traits. Moderately high levels of common twin environment and a small effect for direct isomorphic marital assortment were also found. There was no evidence for cultural transmission, genotype‐environment correlation, or common sibling enviro

ISSN:0741-0395    

DOI:10.1002/gepi.1370040504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThree types of nonrandom sampling of family data are described, and appropriate maximum likelihood methods are proposed for each. The three types arise depending on whether the selection of probands, based on truncation, is applied directly to the phenotypic distribution, to the distribution of a correlated trait, or to the liability distribution of an associated disease. Family data ascertained through random and nonrandom sampling can be analyzed together in a unified approach. Results of a Monte Carlo study are presented that demonstrate the utility of the proposed methods. In particular, likelihood ratio tests of null hypotheses are shown to be distributed as chi‐square, even in samples as small as 50 families (with variable sibship size

ISSN:0741-0395    

DOI:10.1002/gepi.1370040505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMulti‐point linkage analyses of autosomal dominant form of torsion dystonia with linkage groups on chromosomes 11p, 13q, 21q are reported. Analyses are based on family data from a single, large, non‐Jewish pedigree. Large portions of chromosomes 11p and 13q, and virtually the entire long arm of chromosome 21 are excluded from linkage with dystonia. Practical aspects of designing multipoint analyses are discus

ISSN:0741-0395    

DOI:10.1002/gepi.1370040506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFor an autosomal recessive disease, a statistical procedure is developed for detecting nonrandom segregation of marker haplotypes from an unaffected parent to affected children, specifically for the case when the alternative hypothesis of linkage between the disease and marker loci is postulated. The test procedure is locally most powerful and, depending on family size and number of families sampled, any one of the three test statistics proposed can be used. An application of this procedure provides evidence of linkage between tuberculoid leprosy and HLA.

ISSN:0741-0395    

DOI:10.1002/gepi.1370040507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0741-0395    

DOI:10.1002/gepi.1370040501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY