@@ -214,12 +214,6 @@ setMethod("plot_region",

     line_size

 ) {

     sample_anno <- samples(x)

-    exons_anno <- query_exons_region(

-        exons(x),

-        chr = chr,

-        start = start,

-        end = end

-    )

     if (length(window_prop) == 1) {

         window_prop <- c(window_prop, window_prop)

@@ -267,18 +261,30 @@ setMethod("plot_region",

         ) +

             ggplot2::scale_x_continuous(labels = scales::label_number(scale_cut = scales::cut_si("b")))

-    p2 <- plot_gene_annotation(exons_anno, xlim[1], xlim[2]) +

-        ggplot2::coord_cartesian(

-            xlim = xlim,

-            expand = FALSE

-        ) +

-            ggplot2::scale_x_continuous(labels = scales::label_number(scale_cut = scales::cut_si("b")))

+    p_out <- p1

-    anno_height <- attr(p2, "plot_height")

+    # if exon anno exists

+    if (nrow(exons(x)) != 0) {

+        exons_anno <- query_exons_region(

+            exons(x),

+            chr = chr,

+            start = start,

+            end = end

+        )

+

+        p2 <- plot_gene_annotation(exons_anno, xlim[1], xlim[2]) +

+            ggplot2::coord_cartesian(

+                xlim = xlim,

+                expand = FALSE

+            ) +

+                ggplot2::scale_x_continuous(labels = scales::label_number(scale_cut = scales::cut_si("b")))

+        anno_height <- attr(p2, "plot_height")

-    heights <- c(1, 0.075 * anno_height)

-    p_out <- p1 / p2 + patchwork::plot_layout(heights = heights)

+        heights <- c(1, 0.075 * anno_height)

+        p_out <- p1 / p2 + patchwork::plot_layout(heights = heights)

+    }

+    # if heatmap requested

     if (heatmap) {

         p_heatmap <- plot_region_heatmap(x, chr, start, end, window_prop = window_prop) +

             ggplot2::coord_cartesian(