Toxoplasma gondii serointensity and seropositivity: Heritability and household-related associations in the old order amish
JournalInternational Journal of Environmental Research and Public Health
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AbstractToxoplasma gondii (T. gondii) is an intracellular parasite infecting one third of the world’s population. Latent T. gondii infection has been associated with mental illness, including schizophrenia and suicidal behavior. T. gondii IgG antibody titers were measured via ELISA. The heritability of T. gondii IgG was estimated using a mixed model that included fixed effects for age and sex and random kinship effect. Of 2017 Old Order Amish participants, 1098 had positive titers (54.4%). The heritability for T. gondii serointensity was estimated to be 0.22 (p = 1.7 × 10−8 and for seropositivity, it was estimated to be 0.28 (p = 1.9 × 10−5). Shared household environmental effects (i.e., household effects) were also determined. Household effects, modeled as a random variable, were assessed as the phenotypic covariance between any two individuals who had the same current address (i.e., contemporaneous household), and nuclear household (i.e., the phenotypic covariance between parents and children only, not other siblings or spouses). Household effects did not account for a significant proportion of variance in either T. gondii serointensity or T. gondii seropositivity. Our results suggest a significant familial aggregation of T. gondii serointensity and seropositivity with significant heritability. The shared household does not contribute significantly to family aggregation with T. gondii, suggesting that there are possible unmeasured non-household shared and non-shared environmental factors that may play a significant role. Furthermore, the small but significant heritability effects justify the exploration of genetic vulnerability to T. gondii exposure, infection, virulence, and neurotropism. Copyright 2019 by the authors.
Funding: This study was funded by the University of Maryland, Joint Institute for Food Safety and Applied Nutrition and the US Food and Drug Administration (US FDA) through the cooperative agreement FDU.001418 (PI, T.T.P.) Aditionally, this project was also supported in part by the National Institutes of Health , Bethesda Maryland NIH through the pilot/exploratory grant P30 DK072488, and by the CSR&D/Veterans Affairs Administration via a Merit Award (grant number 1 I01 CX001310-01 PI, T.T.P). The results and opinions presented here belong to the authors, and do not represent the official positions of the US FDA, VA, or NIH Acknowledgments: We thank the entire personnel of the University of Maryland School of Medicine Amish Research Clinic, Lancaster, PA, USA, in particular the Amish liaisons, including Naomi Esh and Hanna King, and the nurses of the Amish Research Clinic, including Donna Trubiano, Yvonne Rohrer, Theresa Roomet, Mary Morrissey, Nancy Weitzel and Susan Shaub. We also thank Dr. Michael C. Bazaco for his suggestions and comments and Dr. Anna Spector for her comments on the final proofs of the manuscript.
Identifier to cite or link to this itemhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85073500969&doi=10.3390%2fijerph16193732&partnerID=40&md5=54429e1d4c3fc27fadb6ee4a96e2e73e; http://hdl.handle.net/10713/11238