diff --git a/.Rbuildignore b/.Rbuildignore
index 69460be88249fc6d95a82c05d269b6bd77d9449e..ecdf5798a98ca4a71dfd8693d19c14db91b145ab 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -2,4 +2,6 @@ VarExp.Rproj
 code-of-conduct.md
 README.html
 README.md
-README.Rmd
\ No newline at end of file
+README.Rmd
+^.*\.Rproj$
+^\.Rproj\.user$
diff --git a/R/varFrac.R b/R/varFrac.R
index f03faa5698183b41a7609e9855a23da555c6e826..6f9c860ae1af0f1da16dfd82cafa531df0a93368 100644
--- a/R/varFrac.R
+++ b/R/varFrac.R
@@ -1,4 +1,8 @@
-#' Make sure 
+#' Make sure SNPs in the input file and SNPs included 
+#' in the correlation matrix are the same.
+#'
+#'This step is necessary because some SNPs in the input may be not 
+#'found in the reference panel or excluded from the matrix after the pruning step.
 #'
 #' @param df is the meta-analysis results data frame
 #' @param v is a vector of SNP identifiers