Papillon–Lefèvre syndrome (PLS; OMIM 245000) is an autosomal recessive condition characterized by palmoplantar hyperkeratosis and periodontitis. In 1997, the gene locus for PLS was mapped to 11q14-21, and in 1999, variants in the cathepsin C gene (CTSC) were identified as causing PLS. To date, a total of 75 different disease-causing mutations have been published for the CTSC gene. A summary of recurrent mutations identified in Hungarian patients and a review of published mutations is presented in this update. Comparison of clinical features in affected families with the same mutation strongly confirm that identical mutations of the CTSC gene can give rise to multiple different phenotypes, making genotype–phenotype correlations difficult. Variable expression of the phenotype associated with the same CTSC mutation may reflect the influence of other genetic and/or environmental factors. Most mutations are missense (53%), nonsense (23%), or frameshift (17%); however, in-frame deletions, one splicing variant, and one 5′ untranslated region (UTR) mutation have also been reported. The majority of the mutations are located in exons 5–7, which encodes the heavy chain of the cathepsin C protein, suggesting that tetramerization is important for cathepsin C enzymatic activity. All the data reviewed here have been submitted to the CTSC base, a mutation registry for PLS at http://bioinf.uta.fi/CTSCbase/.

Papillon-Lefévre syndrome (PLS; OMIM 245000) is a rare autosomal recessive condition characterized by symmetrical palmoplantar hyperkeratosis and periodontal inflammation, causing loss of both the deciduous and permanent teeth. PLS develops due to mutations in the cathepsin C gene, CTSC. Recently we have identified a Hungarian PLS family with two affected siblings. Direct sequencing of the coding regions of the CTSC gene revealed a novel seven-base deletion leading to frameshift and early stop codon in the fourth exon of the CTSC gene (c.681delCATACAT, p.T188fsX199). The affected family members carried the mutation in homozygous form, while the clinically unaffected family members carried the mutation in heterozygous form. The unrelated controls carried only the wild type sequence. In this paper we report a novel homozygous deletion of seven bases on the CTSC gene leading to the development of PLS. Since consanguineous marriage was unknown in the investigated family, the presence of the homozygous seven-base deletion of the CTSC gene may suggest that the parents are close relatives.