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Segregation analysis of two lung function indices in a random sample of young families: The humboldt family study
Author(s) -
Chen Yue,
Horne Sandra L.,
Rennie Donna C.,
Dosman James A.
Publication year - 1996
Publication title -
genetic epidemiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.301
H-Index - 98
eISSN - 1098-2272
pISSN - 0741-0395
DOI - 10.1002/(sici)1098-2272(1996)13:1<35::aid-gepi4>3.0.co;2-5
Subject(s) - heritability , sibling , covariate , statistics , mendelian inheritance , locus (genetics) , demography , psychology , mathematics , biology , genetics , developmental psychology , sociology , gene
The Humboldt Family Study was conducted in the town of Humboldt, Saskatchewan, in1993. Familial correlations and segregation analyses of lung function were carried out in 799individuals in 214 nuclear families that included 214 fathers, 214 mothers, and 371 children.Forced expiratory volume in 1 second (FEV 1 ) and maximal mid‐expiratory flowrate (MMFR) were first regressed on age, height, weight, and their quadratic and cubic termsas well as on smoking status in four groups separately (mothers, fathers, daughters, and sons),with terms significant at the 0.10 level being retained. Residual phenotypes were standardizedwithin the four groups. Class D regressive models were used to perform familial correlationsand segregation analyses. For both FEV 1 and MMFR, father‐mother correlationswere not significantly different from zero, and mother‐offspring, father‐offspring, andsibling‐sibling correlations showed no statistically significant difference from each other.Based on the “polygenic” models, the estimated intraclass correlation is 0.132(±0.035) for FEV 1 and 0.171 (±0.039) for MMFR, and thenarrow‐sense heritability is 0.264 for FEV 1 and 0.342 for MMFR. Segregation analysis shows that the “mixed” model with both single locus and polygenic components had a better fit for FEV 1 than single‐locus or polygenic‐only models. However, the model which included a nontransmitted environmental factor [τ(AA) = τ(AB) = τ(BB) = q A ] and polygenic loci had a better fit than the Mendelian model [τ(AA) = 1, τ(AB) = 1/2, τ(BB) = 0] [Akaike's information criterion (AIC) = 2219.47 vs. AIC = 2222.14]. For MMFR, the Mendelian “mixed” model gave a nonsignificant improvement in log e likelihood compared to the simple polygenic model. Comparison of the single‐locus model and Mendelian “mixed” model shows no difference in fitting the data. This study suggests that FEV 1 and MMFR are controlled by many loci with no major effects and/or common environmental factors. © 1996 Wiley‐Liss, Inc.