Table 1. Epistasis analysis for Blister phenotype. Each cell shows the counts of mutants/total worms. “Head-only” and “Full-body” count the number of worms with blisters that showed blisters either restricted to the head region or extending the entire length of the animal. Asterisks report p-values from Fisher’s Exact Test for a difference between the single and double mutant strains for each bli gene and phenotype. ns, not significant, * P < 0.01, ** P < 10^-6.

Genotype	Blisters	Head-only	Full-body
$bli-1$	33/36	3/33	0/33
bli-1; col-182anc	$9/{40}^{\text{**}}$	$9/9^{\text{**}}$	$0/9^{\text{ns}}$
bli-2	39/40	24/39	0/39
bli-2; col-182anc	30/30ns	$7/{30}^{\text{*}}$	$7/{30}^{\text{*}}$