How to put a black border around certain dots on a ggplot geom_point plot

Question

I am trying to make a geom plot using ggplot for some pathways of interest. I would like to put a black border around certain dots that are significant. -log10 > 1.2, so they are easier to identify. Is there anyway to do this in the package so I do not have to do in an illustrator package after I have produced the image? Thank you kindly for advice.

• Image of current dot image:

• Image of raw data:

cols <- c("blue",
          "white",
          "red")

li <- c(-2, 2)

D1 <- ggplot(Practice, aes(Practice$case, Practice$pathway, 
      colour = Enrichment_score, size = Practice$ln)) +
  geom_point(alpha = 0.8) + 
  scale_colour_gradientn(colours = cols) +
  theme(legend.position="bottom") +
  scale_size(breaks = c(0, 1.2, 1.4), range =  c(0.06,12)) +
  guides(size=guide_legend(title = "-log10(q value)"),
         scale_colour_gradient()) +
  labs(colour = "Enrichment Score") +
  theme_bw()
  
D1 + ggtitle("") +
  xlab("") + ylab("") + 
  scale_x_discrete(limits=c("Responder vs Non-responder",
                            "Non-responder vs Control", 
                            "Responder vs Control", 
                            "Case vs Control"))

Answer 1

Another way, which may be simpler, is to use shape 21 with geom_point:

library(ggplot2)

ggplot(mtcars, aes(factor(cyl), mpg)) +
  geom_point(shape = 21,  stroke = 1, aes(colour = disp >= 250, fill = hp)) +
  scale_colour_manual(values = c(`TRUE` = "black", `FALSE` = rgb(0,0,0,0)))

The manual colour scale makes the edge of shape 21 either black or transparent. Note the backticks for TRUE or FALSE.