The Role of Genetic and Environmental Factors in Gout
It’s well known that gouty arthritis (gout) is the most common inflammatory arthritis in the US and in several other countries. Researchers also know that some rare forms of gout are genetic; however, it’s not exactly clear what the relative importance of genetic factors is on the risk for lifetime prevalence of gout.
To investigate this more deeply, researchers performed a heritability analysis for gout and hyperuricemia. They used participants from the National Heart, Lung, and Blood Institute twin study—a prospective observational cohort study.
The results of their findings appeared online in late February 2012 in the article “Nature versus nurture in gout: a twin study.” The article will appear in an upcoming issue of The American Journal of Medicine.
A total of 514 unselected, all-male twin pairs were involved in the study, which included 253 monozygotic (MZ) and 261 dizygotic (DZ) twin pairs.
At baseline, the twins were 48 (±3) years old. Researchers followed them for an average of 34 years.
The research team performed statistical analyses, and they used structural equation models and maximum likelihood methods to do this.
They also used co-variates for adjustment in the structural equation models. Co-variates were identified using bi-variate logistic regressions.
After performing these analyses, researchers found that the lifetime prevalence of gout did not differ between the MZ and DZ twins. They also noted that concordance of hyperuricemia was 53% in MZ and 24% in DZ twin pairs (p<.001).
They used models to quantify the relative contribution of both genetic and environmental factors on phenotypic variance. These models showed that individual variability in gout was substantially influenced by environmental factors the co-twins shared—not by genetic factors. On the other hand, the individual differences in hyperuricemia were influenced significantly by genetic factors.
Researchers concluded that hyperuricemia is genetic. However, risk for gout is determined by a patient’s environment—excluding the context of rare genetic disorders. They suggest that their findings have implications for both the prevention and treatment of gout.