A novel mutation of the cathepsin C gene in Papillon-Lefèvre syndrome

Cathepsin C in health and disease: from structural insights to therapeutic prospects

Cathepsin C (CTSC) is a lysosomal cysteine protease constitutively expressed at high levels in the lung, kidney, liver, and spleen. It plays a key role in the activation of serine proteases in cytotoxic T cells, natural killer cells (granzymes A and B), mast cells (chymase and tryptase) and neutrophils (cathepsin G, neutrophil elastase, proteinase 3) underscoring its pivotal significance in immune and inflammatory defenses. Here, we comprehensively review the structural attributes, synthesis, and function of CTSC, with a focus on its variants implicated in the etiopathology of several syndromes associated with neutrophil serine proteases, including Papillon-Lefevre syndrome (PLS), Haim-Munk Syndrome (HMS), and aggressive periodontitis (AP). These syndromes are characterized by palmoplantar hyperkeratosis, and early-onset periodontitis (severe gum disease) resulting in premature tooth loss. Due to the critical role played by CTSC in these and several other conditions it is being explored as a potential therapeutic target for autoimmune and inflammatory disorders. The review also discusses in depth the gene variants of CTSC, and in particular their postulated association with chronic obstructive pulmonary disease (COPD), COVID-19, various cancers, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, sudden cardiac death (SCD), atherosclerotic vascular disease, and neuroinflammatory disease. Finally, the therapeutic potential of CTSC across a range of human diseases is discussed.

"Oral Manifestations of Patients with Inherited Defect in Phagocyte Number or Function" a systematic review

INTRODUCTION

Inherited phagocyte defects are one of the subgroups of primary immunodeficiency diseases (PIDs) with various clinical manifestations. As oral manifestations are common at the early ages, oral practitioners can have a special role in the early diagnosis.

MATERIALS AND METHODS

A comprehensive search was conducted in this systematic review study and data of included studies were categorized into four subgroups of phagocyte defects, including congenital neutropenia, defects of motility, defects of respiratory burst, and other non-lymphoid defects.

RESULTS

Among all phagocyte defects, 12 disorders had reported data for oral manifestations in published articles. A total of 987 cases were included in this study. Periodontitis is one of the most common oral manifestations.

CONCLUSION

There is a need to organize better collaboration between medical doctors and dentists to diagnose and treat patients with phagocyte defects. Regular dental visits and professional oral health care are recommended from the time of the first primary teeth eruption in newborns.

A novel mutation in the cathepsin C (CTSC) gene in Iranian family with Papillon-Lefevre syndrome

Objectives

In this study, we analyzed the whole exomes of CTSC gene in a family with history of PLS.

Materials and methods

Genomic DNA was extracted from peripheral blood and genotype analysis was performed. The mutated protein sequence was used to find the best possible tertiary structure for homology modeling. The homology modeling of the novel mutation was then performed using the online Swiss‐Prot server. The results were also analyzed for to verify its validity.

Results

The analysis of CTSC gene elucidated a novel insertion GAC. The novel mutation was proved by analyzing 50 healthy control volunteers. Modeling of the novel found mutation in CTSC gene revealed structural defects that may have caused the functional abnormalities.

Conclusions

The structural analysis of the mutated protein model identifies changes in the stereo‐chemical and the energy level of the mutated protein. Since this protein play a role in the activation of granule serine proteases from cytotoxic T lymphocytes, natural killer cells, mast cells, such structural defects may lead to its malfunction causing dysfunctioning of immune defense mechanisms.

Processing and Maturation of Cathepsin C Zymogen: A Biochemical and Molecular Modeling Analysis

Cysteine cathepsin C (CatC) is a ubiquitously expressed, lysosomal aminopeptidase involved in the activation of zymogens of immune-cell-associated serine proteinases (elastase, cathepsin G, proteinase 3, neutrophil serine proteinase 4, lymphocyte granzymes, and mast cell chymases). CatC is first synthetized as an inactive zymogen containing an intramolecular chain propeptide, the dimeric form of which is processed into the mature tetrameric form by proteolytic cleavages. A molecular modeling analysis of proCatC indicated that its propeptide displayed a similar fold to those of other lysosomal cysteine cathepsins, and could be involved in dimer formation. Our in vitro experiments revealed that human proCatC was processed and activated by CatF, CatK, and CatV in two consecutive steps of maturation, as reported for CatL and CatS previously. The unique positioning of the propeptide domains in the proCatC dimer complex allows this order of cleavages to be understood. The missense mutation Leu172Pro within the propeptide region associated with the Papillon-Lefèvre and Haim-Munk syndrome altered the proform stability as well as the maturation of the recombinant Leu172Pro proform.

Clinical and molecular analysis in Papillon-Lefèvre syndrome

Papillon-Lefèvre syndrome (PLS; MIM#245000) is a rare recessive autosomal disorder characterized by palmar and plantar hyperkeratosis, and aggressively progressing periodontitis leading to premature loss of deciduous and permanent teeth. PLS is caused by loss-of-function mutations in the CTSC gene, which encodes cathepsin C. PLS clinical expressivity is highly variable and no consistent genotype-phenotype correlation has been demonstrated yet. Here we report the clinical and genetic features of five PLS patients presenting a severe periodontal breakdown in primary and permanent dentition, hyperkeratosis over palms and soles, and recurrent sinusitis and/or tonsillitis. Mutation analysis revealed two novel homozygous recessive mutations (c.947T>C and c.1010G>C) and one previous described homozygous recessive mutation (c.901G>A), with parents carrying them in heterozygous, in three families (four patients). The fourth family presented with the CTSC c.628C>T mutation in heterozygous, which was inherited maternally. Patient carrying the CTSC c.628C>T mutation featured classical PLS phenotype, but no PLS clinical characteristics were found in his carrier mother. All mutations were found to affect directly (c.901G>A, c.947T>C, and c.1010G>C) or indirectly (c.628C>T, which induces a premature termination) the heavy chain of the cathepsin C, the region responsible for activation of the lysosomal protease. Together, these findings indicate that both homozygous and heterozygous mutations in the cathepsin C heavy chain domain may lead to classical PLS phenotype, suggesting roles for epistasis or gene-environment interactions on determination of PLS phenotypes.

[Gene mutational analyses of cathepsin C gene in a family with Papillon-Lefèvre syndrome]

OBJECTIVE

This study aimed to investigate the gene mutational characteristics of cathepsin C (CTSC) gene in a Chinese patient with Papillon-Lefèvre syndrome (PLS) and further confirm the genetic basis for the phenotype of PLS.

METHODS

Peripheral blood samples were obtained from the PLS proband and his family members (his parents and younger brother) for genomic DNA extraction. The coding region and exon boundaries of the CTSC gene were amplified and sequenced by polymerase chain reaction and direct sequencing of DNA.

RESULTS

Compound heterozygous mutations of CTSC gene were identified in the patient. A heterozygous missense mutation occurred in the 800th base of exon 6, and the base T in the base pair was replaced by C (c.800T>C). The encoded amino acid leucine changed to proline (p. L267P). A heterozygous missense mutation occurred in the 1015th base of exon 7, and base C in the base pair was replaced by T (c.1015C>T). The encoded amino acid arginine changed to cysteine (p.R339C). Among the mutations, c.800T>C originated from the mother, c.1015C>T was identified from the father. No mutations were detected in the younger brother.

CONCLUSIONS

Mutations of CTSC gene are responsible for the phenotype of PLS.

Papillon-Lefèvre syndrome: clinical presentation and management options

Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive disorder, characterized by diffuse palmoplantar keratoderma and precocious aggressive periodontitis, leading to premature loss of deciduous and permanent dentition at a very young age. Various etiopathogenic factors are associated with the syndrome, like immunologic alterations, genetic mutations, and the role of bacteria. Dentists play a significant role in the diagnosis and management of PLS as there are characteristic manifestations like periodontal destruction at an early age and an early eruption of permanent teeth. Here, we are presenting an elaborate review of PLS, its etiopathogenesis, clinical presentation, and management options.

CTSC and Papillon-Lefèvre syndrome: detection of recurrent mutations in Hungarian patients, a review of published variants and database update

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-Lefevre syndrome (PLS) without cathepsin C mutation: A rare early onset partially penetrant variant of PLS

Papillon-Lefevre syndrome (PLS) is a very rare, autosomal recessive syndrome characterized by palmar-plantar hyperkeratosis and severe destructive periodontitis. Most patients present with PLS harbor mutations in the cathepsin C gene, but recent studies have identified individuals with classic PLS symptoms without such mutations. This suggests more genetic heterogeneity for PLS than previously thought. Here we present an individual's manifesting characteristic clinical features of PLS with no mutations in the coding sequence of cathepsin C. We suggest there must be alternative genetic causes for such forms of PLS.

Papillon-lefevre syndrome: Case series and review of literature

Papillon-lefevre syndrome (PLS) belongs to a heterogeneous group of skin diseases that are characterized by hyperkeratosis of palms and soles. It is a type IV palmoplantar keratosis (PPK) while the palmoplantar keratodermas share some features of PPK, they are etiologically heterogeneous. PLS differs from other types of PPK by the presence of severe and early onset periodontitis. Genetic studies have shown that mutation in the major gene locus of chromosome 11q14 with the loss of function of cathepsin-C (CTSC) gene is responsible for PLS. CTSC gene mutations are causative for PLS. The resultant loss of CTSC function is responsible for the severe periodontal destruction seen clinically. This report represents two siblings with classical signs and symptoms of PLS.

Papillon-Lefevre syndrome: A case report of 2 affected siblings

Papillon-Lefèvre syndrome (PLS) is a very rare syndrome of autosomal recessive inheritance characterized by palmar-plantar hyperkeratosis and early onset periodontitis, leading to premature loss of both primary and permanent dentitions. Various etiopathogenic factors are associated with the syndrome, but a recent report has suggested that the condition is linked to x mutations of the cathepsin C gene. The purpose of this report is to describe two cases of PLS in the same family who presented to the Department of Dentistry of Dr. R. P. Government Medical College at Tanda, Kangra (Himachal Pradesh) with a chief complaint of mobility and rapid loss of teeth. Hyperkeratosis of palms and soles was present. On intraoral examination, there was severe gingival inflammation, abscess formation, and deep periodontal pockets with mobility of teeth. Histopathological examination of the specimen taken from the thickened skin was reported to be consistent with PLS. The dental treatment comprised oral prophylaxis, scaling and root planning, antibiotic therapy, instructions on oral hygiene, restorations, extraction of hopelessly affected teeth, and prosthetic rehabilitation.

Identification of novel mutation in cathepsin C gene causing Papillon-Lefèvre Syndrome in Mexican patients

BACKGROUND

Papillon-Lefèvre Syndrome (PLS) is a type IV genodermatosis caused by mutations in cathepsin C (CTSC), with a worldwide prevalence of 1-4 cases per million in the general population. In México, the prevalence of this syndrome is unknown, and there are few case reports. The diagnosis of twenty patients in the state of Sinaloa highlights the need to characterize this syndrome in Mexicans.

METHODS

To understand the basis of PLS in Mexicans, the gene expression, enzymatic activity and mutational analysis of CTSC were assayed in nine PLS patients and their relatives. Frequencies of CTSC gene polymorphisms and HLA alleles were determined in these patients, their relatives, and the population.

RESULTS

Patients showed normal CTSC gene expression, but a deep reduction (up to 85%) in enzymatic activity in comparison to unrelated healthy individuals. A novel loss-of-function mutation, c.203 T > G (p.Leu68Arg), was found in all patients, and some carried the polymorphism c.458C > T (p.Thr153Ile). Allelic frequencies in patients, relatives and controls were 88.89%, 38.24% and 0.25% for G (c.203 T > G); and 11.11%, 8.82% and 9.00% for T (c.458C > T). HLA-DRB1*11 was found significantly more frequent (P = 0.0071) in patients than controls (33.33% vs. 7.32%), with an estimated relative risk of 6.33.

CONCLUSIONS

The novel loss-of function mutation of CTSC gene (c.203 T > G) found in patients correlated with their diminished enzymatic activity, and HLA-DRB1*11 was found to be associated with PLS. The study of more PLS patients may give more insights into the etiology of the disease as well as its prevalence in México.

Cytokine production by leukocytes of Papillon-Lefèvre syndrome patients in whole blood cultures

Papillon-Lefèvre syndrome (PLS) is characterised by aggressively progressive periodontitis combined with palmo-plantar hyperkeratosis. It is caused by "loss of function" mutations in the cathepsin C gene. The hypothesis behind this study is that PLS patients' polymorphonuclear leukocytes (PMNs) produce more proinflammatory cytokines to compensate for their reduced capacity to neutralize leukotoxin and to eliminate Aggregatibacter actinomycetemcomitans. Production of more interleukin (IL)-8 would result in the attraction of more PMNs. The aim of this study was to evaluate the cytokine profile in PLS patients' blood cultures. Blood was sampled from eight PLS patients (one female) from six families (antiinfective therapy completed: six; edentulous: two) with confirmed cathepsin C mutations and deficient enzyme activity. Nine healthy males served as controls. Whole blood cultures were stimulated with highly pure lipopolysaccharide (LPS) from Escherichia coli R515 and IL-1β plus tumor necrosis factor (TNF)-α. Thereafter, release of IL-1β (stimulation: LPS and LPS plus adenosine triphosphate), IL-6, IL-8, interferon-inducible protein (IP)-10, and interferon (IFN)-γ (stimulation: LPS, IL-1β/TNFα) were detected by ELISA. Medians of cytokine release were, with the exception of IP-10, slightly higher for PLS than for controls' cultures. None of these differences reached statistical significance. Increased production of IL-1β, IL-6, IL-8, IP-10, or IFNγ as a significant means to compensate for diminished activity and stability of polymorphonuclear leukocyte-derived proteases could not be confirmed in this study. Cytokine profiles in blood cultures may not be used to identify PLS patients.

Papillon-Lefevre syndrome: A case report

Papillon-Lefevre syndrome (PLS) is a rare autosomal recessive disorder of keratinization, characterized by palmoplantar hyperkeratosis, periodontal involvement and precocious loss of dentition. The purpose of this report was to describe the case of an 18-year-old girl who presented to the out patient department of Navodaya Dental College and Hospital, Raichur, Karnataka, India, with the chief complaint of multiple loss of teeth. Her gingiva appeared erythematous, edematous and bled readily on probing, and the teeth were mobile. Hyperkeratosis of palms and soles were found. These findings are consistent with Papillon-Lefèvre syndrome. The clinical presentation, differential diagnosis, complications and management of this syndrome are discussed.

Oral and Dermatologic Findings in Two siblings with Papillon-Lefevre Syndrome: Review of the Literature

Papillon-Lefevre syndrome (PLS), first described in 1924, is a rare autosomal recessive disorder characterized by early onset palmoplanter hyperkeratosis and severe generalized destructive periodontitis leading to premature loss of both primary and permanent dentitions. PLS usually manifest itself between the ages of six months to four years, coinciding with the eruption of primary teeth. The proband becomes completely edentulous by the age of 15.

Functional Cathepsin C mutations cause different Papillon-Lefèvre syndrome phenotypes

AIM

The autosomal-recessive Papillon-Lefèvre syndrome (PLS) is characterized by severe aggressive periodontitis, combined with palmoplantar hyperkeratosis, and is caused by mutations in the Cathepsin C (CTSC) gene. This study aimed to identify CTSC mutations in different PLS phenotypes, including atypical forms and isolated pre-pubertal aggressive periodontitis (PAP).

MATERIAL AND METHODS

Thirteen families with different phenotypes were analysed by direct sequencing of the entire coding region and the regulatory regions of CTSC. The function of novel mutations was tested with enzyme activity measurements.

RESULTS

In 11 of 13 families, 12 different pathogenic CTSC mutations were found in 10 typical PLS patients, three atypical cases and one PAP patient. Out of four novel mutations, three result in protein truncation and are thus considered to be pathogenic. The homozygous c.854C>T nucleotide exchange (p.P285L) was associated with an almost complete loss of enzyme activity. The observed phenotypic heterogeneity could not be associated with specific genotypes.

CONCLUSIONS

The phenotypic variability of the PLS associated with an identical genetic background may reflect the influence of additional genetic or environmental factors on disease characteristics. CTSC mutation analyses should be considered for differential diagnosis in all children suffering from severe aggressive periodontitis.

Novel mutations of cathepsin C gene in two Chinese patients with Papillon-Lefèvre syndrome

Papillon-Lefèvre syndrome (PLS) is an inherited human disease characterized by early-onset periodontitis and palmoplantar hyperkeratosis. Mutations of the lysosomal protease cathepsin C (CTSC) gene have been shown to be the genetic cause of Papillon-Lefèvre syndrome. There are several case reports in China, while there has been no study on the genetic analysis of PLS. We studied two Chinese patients carrying Papillon-Lefèvre syndrome and showing premature tooth loss and palmoplantar hyperkeratosis. Mutation screening and sequence analysis of the CTSC gene revealed a compound heterozygous mutation (c.415 G>A and c.778 T>C) in one patient, and two novel compound heterozygous mutations (c.851G>A and c.112delCCTG) in the other patient. Our novel discovery indicates that the phenotypes observed in these two patients are due to the CTSC gene mutation.

Phenotypic variation and allelic heterogeneity in young patients with Papillon-Lefèvre syndrome

Papillon-Lefèvre syndrome is an autosomal recessive disorder characterized by palmoplantar hyperkeratosis and aggressive periodontitis. The aim of the study was to identify underlying cathepsin C mutations in 39 subjects with Papillon-Lefèvre syndrome and to explore any phenotypic associations. Genotyping and mutation analyses were performed using standard molecular techniques, and dermatological and oral characteristics were assessed with a semiquantitative clinical score. Three genotypes were present at microsatellite marker D11S1780 and two underlying mutations were identified. The most common genotype (183/183) was associated with an 815G --> C mutation in exon 6 resulting in an arginine to proline change at amino acid 272 (R272P). Patients with the 173/173 genotype revealed an exon 7 G300D mutation resulting in a glycine to aspartic acid change at amino acid 300. The mutation in a family with 189/189 genotype remained unknown. A significant difference in hyperkeratosis of the feet was found between the patients with mutations G300D and R272P ( p < 0.05), but not regarding hands or periodontal condition. Young girls displayed significantly less palmoplantar hyperkeratosis ( p < 0.05) than young boys. In conclusion, considerable phenotypic heterogeneity was observed within the two cardinal mutations and in the 189/189 genotype.

Description of two new cathepsin C gene mutations in patients with Papillon-Lefèvre syndrome

BACKGROUND

Papillon-Lefèvre syndrome (PLS) is a rare autosomal disorder characterized by severe periodontitis and palmar plantar hyperkeratosis (PPK). PLS is caused by mutations in the cathepsin C (CTSC) gene. Dipeptidyl peptidase I (DPPI) encoded by the CTSC locus removes dipeptides from the amino terminus of the protein substrate and mainly plays an important role in immune and inflammatory processes. Several mutations have been reported in this gene in patients with PLS. This study reports two novel deletion mutation of the CTSC gene in two Indian families with PLS.

METHODS

Peripheral blood samples were obtained for genomic DNA isolation from individuals belonging to two Indian families. Exon-specific intronic primers were used to amplify DNA from all individuals, and the PCR products were subsequently sequenced to detect the mutations. Heteroduplex analysis (HDA) was used to confirm heterozygosity and to determine the presence of mutations in control individuals.

RESULTS

All patients from both families had a classic PLS phenotype, which included PPK and severe periodontitis. Sequence analysis of the CTSC gene revealed two novel deletion mutations, one (1213-1215delCAT) in exon 7 and the other (629-630delGA) in exon 4 of the CTSC gene. For both mutations, the patients were homozygous, whereas the parents were heterozygous.

CONCLUSIONS

This study reports two novel deletion mutations in two Indian families with PLS. One of the mutations introduces a premature stop codon, thereby producing a truncated protein. In the other case, the mutation observed leads to the loss of a highly conserved histidine molecule that is present in the active site of the enzyme. In both cases, mutations may result in a conformation change, causing loss of the enzymatic activity.

Papillon-Lefèvre syndrome with albinism: A review of the literature and report of 2 brothers

BACKGROUND

Papillon-Lefèvre syndrome (PLS) is a very rare autosomal recessive disorder characterized by palmoplantar hyperkeratosis and severe early onset of destructive periodontitis leading to premature loss of both primary and permanent dentitions. The etiopathogenesis of the condition suggests that there is a genetic basis for susceptibility to specific virulent pathogens. Variation in the clinical presentation of PLS has recently been observed.

OBJECTIVE

The objective was to present the first report, which describes the concurrence of PLS and albinism. The etiology, pathology, and management of the condition were reviewed and genetic analysis was performed. SUBJECTS AND CLINICAL PRESENTATION: The probands are Jordanian brothers aged 13 and 20 years on their initial presentation. The parents were second cousins and not affected. The patients exhibited the typical clinical features of PLS with type 1 oculocutaneous albinism (OCA1). They also had increased susceptibility to infection manifested in recurrent tonsillitis, respiratory tract infection, pyoderma, onychogryphosis, and other pathosis. Skin biopsy demonstrated hyperkeratosis, focal parakeratosis, hypergranulosis, and acanthosis. Ectopic calcification of the dura was noticed in one of the probands. Hematological parameters tested were within the normal limits. The probands were tested for mutations in the causative genes of PLS and OCA1, cathepsin C (CTSC), and tyrosinase, respectively. Independent mutations (c.318-1G>A and c.817G>C/p.W272C) were identified in CTSC and tyrosinase, respectively. The probands were homozygous and their sister who had only PLS was homozygous for the same (CTSC) mutation but heterozygous for tyrosinase gene.

CONCLUSION

We hope that this report of coinheritance PLS and albinism will initiate further investigations to disclose other possible variations that may enhance our knowledge on gene mutations of this intriguing syndrome.

Effect of genetic variability on the inflammatory response to periodontal infection

AIM

To review the association between genetic variability and the inflammatory response induced by periodontal infection.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed from January 2000 up to and including March 2005. The search included all types of publications, published in English without other limitations. The following search terms were used: "cytokine polymorphism", "gene polymorphism", "periodontitis", "gingivitis", "inflammation" and "host-response". The papers resulting from the above search were used as an additional source for relevant articles.

RESULTS

Genetic variability was examined for the correlation to clinical indicators of inflammation such as bleeding on probing (BOP), gingival inflammation, cytokine in gingival crevicular fluid (GCF) and cytokine production by inflammatory cells. According to the current literature, most of the studies found no association between genetic variability and BOP, gingival inflammation or cytokine concentrations in the GCF. These studies were hampered by inappropriate study designs and the use of inflammatory parameters as secondary rather than primary outcome variables. The data suggest that the production of inflammatory mediators by inflammatory cells may be affected by different genetic traits but further studies are needed in order to establish this association.

CONCLUSIONS

To date, there is no clear correlation between any of the gene polymorphisms and clinical indicators of inflammation. The powering of studies to reveal associations between single or multiple nucleotide polymorphisms and inflammatory parameters will need to involve a much larger number of subjects than were used in the past. The available data (including the interleukin-1 composite genotype) do not currently support the utility of such tests in the diagnosis and prognostic assessments of periodontal diseases.

A homozygous cathepsin C mutation associated with Haim-Munk syndrome

Haim-Munk syndrome (HMS) is a rare autosomal recessive disorder characterized clinically by abnormal palmoplantar hyperkeratosis and destruction of the periodontium, with hallmarks of onychogryphosis and arachnodactyly. Germline mutations in the lysosomal protease cathepsin C gene (CTSC) have been described in a single patient with HMS and in several individuals with the clinically related disorder Papillon-Lefevre syndrome (PLS). We describe a patient with HMS. We have analysed the cathepsin C gene in the proband and her mother. Sequence analysis of CTSC in the proband revealed a homozygous mutation at codon 196 (587T-->C) within exon 4 that altered the conserved leucine to proline (Leu196Pro), whereas the patient's mother was heterozygous for that mutation. The same mutation has previously been described in an unrelated Brazilian family with PLS. An identical single missense mutation in the cathepsin C gene may underlie both PLS and HMS. These findings confirm that HMS and PLS are allelic variants of cathepsin C gene mutations and suggest that other factors (environmental or genetic) may be important determinants of the clinical phenotype of HMS and PLS.

The role of cathepsin C in Papillon-Lefèvre syndrome, prepubertal periodontitis, and aggressive periodontitis

We have previously reported that loss-of-function mutations in the cathepsin C gene (CTSC) result in Papillon-Lefèvre syndrome, an autosomal recessive condition characterized by palmoplantar keratosis and early-onset, severe periodontitis. Others have also reported CTSC mutations in patients with severe prepubertal periodontitis, but without any skin manifestations. The possible role of CTSC variants in more common types of non-mendelian, early-onset, severe periodontitis ("aggressive periodontitis") has not been investigated. In this study, we have investigated the role of CTSC in all three conditions. We demonstrate that PLS is genetically homogeneous and the mutation spectrum that includes three novel mutations (c.386T>A/p.V129E, c.935A>G/p.Q312R, and c.1235A>G/p.Y412C) in 21 PLS families (including eight from our previous study) provides an insight into structure-function relationships of CTSC. Our data also suggest that a complete loss-of-function appears to be necessary for the manifestation of the phenotype, making it unlikely that weak CTSC mutations are a cause of aggressive periodontitis. This was confirmed by analyses of the CTSC activity in 30 subjects with aggressive periodontitis and age-sex matched controls, which demonstrated that there was no significant difference between these two groups (1,728.7 +/- SD 576.8 micro moles/mg/min vs. 1,678.7 +/- SD 527.2 micro moles/mg/min, respectively, p = 0.73). CTSC mutations were detected in only one of two families with prepubertal periodontitis; these did not form a separate functional class with respect to those observed in classical PLS. The affected individuals in the other prepubertal periodontitis family not only lacked CTSC mutations, but in addition did not share the haplotypes at the CTSC locus. These data suggest that prepubertal periodontitis is a genetically heterogeneous disease that, in some families, just represents a partially penetrant PLS.

Mutation analysis of the cathepsin C gene in Indian families with Papillon-Lefèvre syndrome

BACKGROUND

PLS is a rare autosomal recessive disorder characterized by early onset periodontopathia and palmar plantar keratosis. PLS is caused by mutations in the cathepsin C (CTSC) gene. Dipeptidyl-peptidase I encoded by the CTSC gene removes dipeptides from the amino-terminus of protein substrates and mainly plays an immune and inflammatory role. Several mutations have been reported in this gene in patients from several ethnic groups. We report here mutation analysis of the CTSC gene in three Indian families with PLS.

METHODS

Peripheral blood samples were obtained from individuals belonging to three Indian families with PLS for genomic DNA isolation. Exon-specific intronic primers were used to amplify DNA samples from individuals. PCR products were subsequently sequenced to detect mutations. PCR-SCCP and ASOH analyses were used to determine if mutations were present in normal control individuals.

RESULTS

All patients from three families had a classic PLS phenotype, which included palmoplantar keratosis and early-onset severe periodontitis. Sequence analysis of the CTSC gene showed three novel nonsense mutations (viz., p.Q49X, p.Q69X and p.Y304X) in homozygous state in affected individuals from these Indian families.

CONCLUSIONS

This study reported three novel nonsense mutations in three Indian families. These novel nonsense mutations are predicted to produce truncated dipeptidyl-peptidase I causing PLS phenotype in these families. A review of the literature along with three novel mutations reported here showed that the total number of mutations in the CTSC gene described to date is 41 with 17 mutations being located in exon 7.