Several mutations in the FIG4-encoding gene were found to cause Yunis–Varon syndrome. Some of these mutations result in complete loss of protein function; others involve amino-acid replacements at highly conserved residues.
Mutations in the FIG4 gene, which encodes for a specific protein, have been linked to Yunis–Varon syndrome. The mutations can either render the protein non-functional or substitute amino acids at critical sites.