Defense Date

2009

Document Type

Thesis

Degree Name

Master of Science

Department

Periodontics

First Advisor

John Gunsolley

Abstract

AIM: This study aims to determine what portion of specific autoantibody phenotypes are genetically determined by using a twin model. METHODS: This study specifically examines Anti-Ro(SSA), Anti-La (SSB), Anti-Sn/RNP, Anti-Sm, Anti-Jo-1, Anti-Scl-70, Anti-Tg & Anti-TPO, Anti-dsDNA, Anti-PS, and Anti-cardiolipin antibodies for their heritability. This study examined 104 same-sex adult twins (66 monozygous, 38 dizygous) for the above mentioned autoantibody values. The serum autoantibody values in each subject were quantified using automated ELISA. Descriptive statistics including, distributions, quantiles, and moments were calculated by zygosity for continuous antibody values, subject ages, gender, race and smoking status. Categorical antibody levels were used to determine twin pair concordance rates. Continuous and rank ordered autoantibody values were used to determine the presence and portion of a genetic component. To evaluate how strongly the antibody values in each twin group resembled each other, the intraclass correlation was calculated for each antibody by zygosity. The genetic variances, environmental variances, and heritability were estimated using path models with maximum likelihood estimation techniques. The phenotypic variance was modeled as a linear function of underlying additive genetic (A), dominant genetic (D), common environmental (C), and random environmental (E) effects. RESULTS: Several antibodies demonstrated a genetic component in our study population. Anti-cardiolipin had a genetic component with an estimated 69% heritability. Anti-dsDNA yielded a genetic component with a heritability estimate of 55-62%. Anti-Jo-1 presented a genetic component with the heritability estimate to be 41-51%. Anti-SCL-70 demonstrated a genetic component with a heritability estimate of 42-59%. Anti-PL had a genetic component with a heritability estimate of 52-54%. Several antibodies did not have a measurable genetic component. These included anti-Sm, anti-Ro(SSA), anti-La(SSB), anti-sn/RNP, anti-Tg, and anti-TPO. Some possibilities for the lack of a measureable genetic component may be due to the limited number of discordant twin pairs and/or the small number of subjects with higher levels of antibodies. CONCLUSION: The results of this study suggest several clinically relevant markers of auto-immunity may be partially genetically determined. These include: anti-cardiolipin, anti-dsDNA, anti-Jo-1, anti-SCL-70, and anti-phospholid.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

July 2009

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