Papillon-Lefèvre syndrome (PLS) is an inherited human disorder characterised by premature destruction of the periodontium of the deciduous and permanent teeth, palmoplantar hyperkeratosis, and increased susceptibility to bacterial infections during the first years of life. In this paper two PLS families have been studied. Family 1 presents a novel homozygous mutation (880T>C) in exon 6 causing Y294H amino acid substitution. Family 2 shows a previously described non-sense homozygous punctual change (72C>A) that introduces a termination codon at the extracellular domain of the protein (C24X).