Statistical Power of Rare Variant Analysis on Serum Urate Levels

Abstract

Gout is a common arthritis caused by monosodium urate crystals. Familial studies have shown that the heritability of serum urate levels is estimated to be 30-70%. By a gene-based test, a recent study suggested that rare variants are major contributors to the heritability of serum urate levels. Gene-based analysis considers the effect of multiple genetic variants in one gene in a single test. In this article, the relationship between the sample size and potency of a gene-based test was examined. We divided a hypothetical population into two groups: those who have rare variations and those who do not. It was considered that the difference in uric acid concentrations between the two groups was the same as the difference caused by the presence or absence of URAT1 variants in previous studies. Uric acid levels in each person were also considered to follow a normal distribution, with the expectation being the average of the group to which the person belonged. Under these conditions, the statistical power of the gene-based test was computed. The results showed that the gene-based test boosted the power of the test so that rare variants were detected in far fewer people than the SNP-based test. This study suggests the potential for studying "common diseases, rare variations" by a gene-based test, in addition to "common diseases, common variations.”