Confirmation of oxidative stress and fatty acid disturbances in two further Papillon-Lefèvre syndrome families with identification of a new mutation

BACKGROUND

We have previously reported oxidative and fatty acids disturbances in one Papillon-Lefèvre syndrome (PLS) family. This Mendelian condition characterized by palmar plantar keratosis and severe aggressive periodontitis, is caused by mutations in the cathepsin C (CTSC) gene. In this study, we have analysed two further unrelated PLS families to confirm this association.

METHODS

Mutations were identified by direct sequencing of CTSC. Biochemical analyses were performed in probands and their relatives in order to determine plasma levels of vitamin E, CoQ10 , lipid hydroperoxides (HP) and fatty acid patterns.

RESULTS

Pathogenic CTSC mutations were identified in both families including a new mutation (c504C>G). Both probands showed low levels of vitamin E and CoQ10 , and high levels of lipid HP, and also very low levels of docohexaenoic acid.

CONCLUSIONS

The previously reported oxidative and fatty acids disturbances were confirmed as a feature of this condition in two further families. There are low levels of antioxidant markers and high levels of oxidative markers, in addition of low levels of some anti-inflammatory fatty acids in persons suffering PLS and some of their relatives.

Screening programmes for the early detection and prevention of oral cancer

BACKGROUND

Screening programmes for major cancers, such as breast and cervical cancer have effectively decreased the mortality rate and helped to reduce the incidence of these cancers. Although oral cancer is a global health problem with increasing incidence and mortality rates, no national population-based screening programmes for oral cancer have been implemented. To date there is debate on whether to employ screening methods for oral cancer in the daily routine work of health providers.

OBJECTIVES

To assess the effectiveness of current screening methods in decreasing oral cancer mortality.

SEARCH STRATEGY

Electronic databases (MEDLINE, CANCERLIT, EMBASE, the Cochrane Central Register of Controlled Trials; 1966 to July 2005, The Cochrane Library - Issue 3, 2005), bibliographies, handsearching of specific journals and contact authors were used to identify published and unpublished data.

SELECTION CRITERIA

Randomised controlled trials of screening for oral cancer or precursor oral lesions using visual examination, toluidine blue, fluorescence imaging or brush biopsy.

DATA COLLECTION AND ANALYSIS

The search found 112 citations and these have been reviewed. One randomised controlled trial of screening strategies for oral cancer was identified as meeting the review's inclusion criteria. Validity assessment, data extraction and statistics evaluation were undertaken by two independent review authors.

MAIN RESULTS

One 10-year randomised controlled trial has been included (n = 13 clusters: 191,873 participants). There was no difference in the age-standardised oral cancer mortality rates for the screened group (16.4/100,000 person-years) and the control group (20.7/100,000 person-years). Interestingly, a significant 34% reduction in mortality was recorded in high-risk subjects between the intervention cohort (29.9/100,000 person-years) and the control arm (45.4/100,000). However, this study has some methodological weaknesses. Additionally, the study did not provide any information related to costs, quality of life or even harms of screening from false-positive or false-negative findings.

AUTHORS' CONCLUSIONS

Given the limitation of evidence (only one included randomised controlled trial) and the potential methodological weakness of the included study, it is valid to say that there is insufficient evidence to support or refute the use of a visual examination as a method of screening for oral cancer using a visual examination in the general population. Furthermore, no robust evidence exists to suggest that other methods of screening, toluidine blue, fluorescence imaging or brush biopsy, are either beneficial or harmful. Future high quality studies to assess the efficacy, effectiveness and costs of screening are required for the best use of public health resources. In addition, studies to elucidate the natural history of oral cancer, prevention methods and the effectiveness of opportunistic screening in high risk groups are needed. Future studies on improved treatment modalities for oral cancer and precancer are also required.

British Society for Oral and Maxillofacial Pathology, UK: minimum curriculum in oral pathology

This paper describes a minimum curriculum in oral pathology for undergraduate dental education in the United Kingdom prepared by the Teachers Group of The British Society of Oral and Maxillofacial Pathology. Curricular development in UK dental schools is overseen by the General Dental Council (GDC), the Quality Assurance Agency for Higher Education (QAA) and the European Union. These organisations define the framework for education and learning outcomes but provide little or no detailed guidance on syllabus or curriculum. This recommended minimum curriculum has been drawn up by a consensus process involving teachers of oral pathology from all 13 UK and one Irish dental schools and is cross-referenced to the GDC and QAA published requirements for undergraduate dental education.

Dento-osseous changes as diagnostic markers in familial adenomatous polyposis families

BACKGROUND

We have previously described a weighted index for determining the diagnostic significance of dento-osseous changes observed on dental panoramic radiographs (DPRs) in individuals at 50% risk of inheriting Familial Adenomatous Polyposis (FAP). A diagnostic test based on this index (Dental Panoramic Radiograph Score, DPRS) was shown to have a sensitivity of 69% and specificity of 100%.

OBJECTIVES

To evaluate the validity of the diagnostic test in an independent sample of individuals at 50% risk of inheriting FAP.

DESIGN

A retrospective assessment of DPRs in individuals at 50% risk of inheriting FAP.

SUBJECTS AND METHODS

A final year dental student assessed blindly and independently, DPRs from an independent sample (n = 119) of affected (n = 26), unaffected (n = 78) and clinically low risk individuals (n = 15). This revealed a sensitivity and specificity of 62 and 97% respectively which is in close agreement with results of the previous study. The dental student's training in assessing DPRs was previously tested using radiographs from 81 individuals from our original study. Weighted Kappa statistics were used to test for agreement. A kappa score of 0.82 (95% confidence interval 0.70-0.93) indicated almost perfect agreement.

MAIN OUTCOME

The DPRS is a reproducible and valid index for assessing the diagnostic significance of dentoosseous changes, in individuals at 50% risk of FAP, even in relatively inexperienced hands.

Screening programmes for the early detection and prevention of oral cancer

BACKGROUND

Although the second half of the last century has generated a rich and complex body of knowledge, the burden of oral cancer is still largely present. As with other cancers, there has been a strong debate whether screening strategies for oral cancer such as visual examination, the use of toluidine blue or newer methods such as brush biopsy or fluorescence imaging are effective in reducing the mortality rate associated with oral cancer.

OBJECTIVES

To assess the effectiveness of current screening methods in decreasing oral cancer mortality.

SEARCH STRATEGY

Electronic databases (MEDLINE, CANCERLIT, EMBASE, the Cochrane Central Register of Controlled Trials; 1966 to September 2002, The Cochrane Library - Issue 2, 2002), bibliographies, handsearching of specific journals and contact authors were used to identify published and unpublished data.

SELECTION CRITERIA

Randomised controlled trials of screening for oral cancer or potentially premalignant oral lesions using visual examination, toluidine blue, fluorescence imaging or brush biopsy.

DATA COLLECTION AND ANALYSIS

The search found 100 citations and these have been reviewed. One randomised controlled trial of screening strategies for oral cancer was identified as meeting the review's inclusion criteria. Validity assessment, data extraction and statistics evaluation have been undertaken by two independent reviewers.

MAIN RESULTS

One ongoing randomised controlled trial has been included (n = 13 clusters: 153,708 eligible subjects, 130,799 included subjects). There was no difference in the age-standardised oral cancer mortality rates for the screened group (21.2/1000,000 person years) and the control group (21.3/100,000 person years). However this study has some methodological weaknesses.

REVIEWER'S CONCLUSIONS

Given the limitation of evidence (only one included randomised controlled trial) and the potential methodological weakness in the included study, it is valid to say that there is no evidence to support or refute the use of a visual examination as a method of screening for oral cancer using a visual examination in the general population. Furthermore, no robust evidence exists to suggest other methods of screening, toluidine blue, fluorescence imaging or brush biopsy, are either beneficial or harmful. Further cost-effective, high quality studies to assess the efficacy and effectiveness of screening are required. In addition, studies to elucidate the natural history of oral cancer, prevention methods and the effectiveness of opportunistic screening in high risk groups are needed.

Patterns of CDKN2A gene loss in sequential oral epithelial dysplasias and carcinomas

The CDKN2A gene locus encodes two different proteins derived from alternative splicing. p16 (exons 1alpha, 2, and 3) acts as a G1 cell cycle regulator, and p14ARF (exons 1beta, 2, and 3) acts to modulate MDM2-mediated degradation of p53. Inactivation of p16 is a common finding in many cancers; however, there is little data on CDKN2A gene abnormalities in oral precancer. In this longitudinal study, we examined changes in the CDKN2A gene locus in sequential epithelial dysplasias and oral carcinomas from 11 patients. Genomic DNA was extracted from laser-microdissected lesional tissue, and exons 1alpha, 1beta, and 2 were analyzed by duplex PCR. Immunohistochemistry was done to identify p16 and p14ARF protein expression. Two adjacent polymorphic microsatellite markers were used for allelotyping. Homozygous deletion of exon 1alpha was identified in 2 of 17 (12%) precancerous lesions. Loss of either exon 1alpha, exon 2, or both was seen in seven of nine (78%) carcinomas. In five of these carcinomas, there was loss of only exon 1alpha. No case showed deletion of exon 1beta. In 5 of 11 patients, microsatellite markers showed differing patterns of allelic imbalance in the precancerous lesions and the subsequent carcinoma, suggesting a complex genetic pattern of progression from dysplasia to carcinoma. We conclude that during oral carcinogenesis homozygous deletion of exon 1alpha of the CDKN2A gene is common but that deletion of exon 2 and 1beta is less frequent. Moreover, our results suggest that the progression from oral precancer to cancer, in some cases, is more complex genetically than predicted by linear models of carcinogenesis.

Medical students' experience with psychiatric diagnoses in a family medicine clerkship

BACKGROUND

Many medical schools require a family medicine clerkship, yet little is known about the quantity and diversity of the diagnoses encountered by the students.

PURPOSE

This study examines patients encountered with psychiatric diagnoses using quantitative data collected by students in a family practice clerkship.

METHODS

Over a 2-year period, 445 students completed 3,320 patient encounter forms for patients with a psychiatric diagnosis, noting their comfort level and responsibilities.

RESULTS

The patients' diagnoses reflect those seen in a typical family practice. Of the 71,869 presenting diagnoses, 3,548 were for a psychiatric condition, most commonly depression (37.1%) and neuroses (28.0%). Students reported a high level of comfort in diagnosing and treating patients with a psychiatric disorder. The students routinely discussed these cases with their preceptors.

CONCLUSIONS

By using a relatively simple computerized database, many curricular issues can be identified. For example, analysis of the database shows that the clerkship provides students with substantial practice in taking patient histories and performing initial patient examinations in patients presenting with a psychiatric problem. However, students infrequently provided patient education and counseling to patients with psychiatric disorders. Specific psychiatric diagnoses reflecting limited experience and lower levels of perceived competence include attention deficit disorder and senile and presenile organic psychotic disorders.

Increasing incidence of oral cancer amongst young persons: what is the aetiology?

The reasons for an increasing incidence of oral cancer, particularly amongst younger persons is unclear. It has been hypothesised either to be a result of an increase in exposure to known risk factors amongst certain groups in the community, or to be due to new aetiological agents. Prior to conducting large expensive population-based studies, it seems appropriate to conduct initial smaller-scale surveys to assess evidence for each of these two hypotheses. This survey of young persons with oral cancer suggest that most are exposed to traditional risk factors of tobacco smoking, drinking alcohol and a low consumption of fruit and vegetables.

DNA studies underestimate the major role of CDKN2A inactivation in oral and oropharyngeal squamous cell carcinomas

Loss of CDKN2A expression was demonstrated by immunohistochemistry in 87% of oral and oropharyngeal squamous cell carcinoma (OSCC) primary tumor samples. By contrast, DNA studies showed a much lower frequency of loss of the CDKN2A gene. Point mutations and promoter methylation of CDKN2A were seen in 7% and 23%, respectively, of primary tumors. Loss of heterozygosity analysis using a dense set of 9p markers showed allelic imbalance that included CDKN2A in only 31% of samples, but a further 47% showed loss at loci near CDKN2A with apparent retention of CDKN2A. No tumor with any allelic imbalance expressed CDKN2A, whether or not the imbalance appeared to involve the CDKN2A locus. We interpret these data as showing partially overlapping deletions on the two 9p homologues, with homozygous deletion of CDKN2A masked by amplification of contaminating stromal material. Our data show that inactivation of the CDKN2A gene products is a near-universal step in the development of oral and oropharyngeal squamous cell carcinomas, and we suggest that homozygous deletion is the most common mechanism of inactivation. The CDKN2A locus may be particularly prone to deletion because it encodes two unrelated tumor suppressor proteins, CDKN2A (p16INK4a) and p19ARF, and deletion, but not point mutation or methylation, would inactivate both gene products. However, our results also suggest that complex patterns of allelic imbalance in primary squamous carcinomas in general may not provide reliable evidence for the existence of multiple tumor suppressor genes within a single chromosomal region.

Role of p16/MTS1, cyclin D1 and RB in primary oral cancer and oral cancer cell lines

One of the most important components of G1 checkpoint is the retinoblastoma protein (pRB110). The activity of pRB is regulated by its phosphorylation, which is mediated by genes such as cyclin D1 and p16/MTS1. All three genes have been shown to be commonly altered in human malignancies. We have screened a panel of 26 oral squamous cell carcinomas (OSCC), nine premalignant and three normal oral tissue samples as well as eight established OSCC cell lines for mutations in the p16/MTS1 gene. The expression of p16/MTS1, cyclin D1 and pRB110 was also studied in the same panel. We have found p16/MTS1 gene alterations in 5/26 (19%) primary tumours and 6/8 (75%) cell lines. Two primary tumours and five OSCC cell lines had p16/MTS1 point mutations and another three primary and one OSCC cell line contained partial gene deletions. Six of seven p16/MTS1 point mutations resulted in termination codons and the remaining mutation caused a frameshift. Western blot analysis showed absence of p16/MTS1 expression in 18/26 (69%) OSCC, 7/9 (78%) premalignant lesions and 8/8 cell lines. One cell line, H314, contained a frameshift mutation possibly resulting in a truncated p16/MTS1 protein. pRB was detected in 14/25 (56%) of OSCC but only 11/14 (78%) of these contained all or some hypophosphorylated (active) pRB. In premalignant samples, 6/8 (75%) displayed pRB, and all three normal samples and eight cell lines analysed contained RB protein. p16/MTS1 protein was undetectable in 10/11 (91%) OSCCs with positive pRB. Overexpression of cyclin D1 was observed in 9/22 (41%) OSCC, 3/9 (33%) premalignant and 8/8 (100%) of OSCC cell lines. Our data suggest p16/MTS1 mutations and loss of expression to be very common in oral cancer cell lines and less frequent in primary OSCC tumours. A different pattern of p16/MTS1 mutations was observed in OSCC compared to other cancers with all the detected p16/MTS1 mutations resulting in premature termination codons or a frameshift. The RB protein was expressed in about half (44%) of OSCCs and its expression inversely correlated with p16/MTS1 expression. In conclusion, we show that abnormalities of the RB pathway are a common mechanism of oral carcinogenesis.

Frequent allelic loss and homozygous deletion in chromosome band 8p23 in oral cancer

Frequent loss of heterozygosity on chromosome 8p in a variety of human malignancies, including head and neck cancers, has suggested the presence of a tumor suppressor gene (or genes) associated with the pathogenesis of these cancers. To test the role of genetic alterations at 8p23 in oral carcinogenesis, we studied 51 squamous cell carcinomas of the head and neck and 29 oral squamous cell carcinoma cell lines for allelic loss using 7 microsatellite markers spanning approximately 5 cM of chromosome band 8p23. Twenty-three of 51 tumors (45%) and 23 of 29 cell lines (79%) showed allelic loss at 1 or more loci. Three cell lines showed homozygous deletion of loci within a 3 cM region defined by the markers D8S1781 and D8S262. Our results suggest that a tumor suppressor gene (or genes) is located in 8p23 and is associated with the development and/or progression of oral carcinomas.

Differential diagnosis of type 2 neurofibromatosis: molecular discrimination of NF2 and sporadic vestibular schwannomas

Patients who present with unilateral vestibular schwannomas either at a young age or with additional features of type 2 neurofibromatosis (NF2) are at risk of developing bilateral disease and transmitting a risk of neurogenic tumours to their offspring. We have identified 15 patients from a series of 537 with unilateral vestibular schwannomas who also had one or more of the following: other tumours (10/15), features of NF2 (3/15), or a family history of neurogenic tumours (5/15). No germline NF2 mutations were detected and in 7/9 cases where tumour material was available for analysis a germline mutation in the NF2 gene has been excluded. Although a possibility of gonosomal mosaicism still exists, exclusion tests for the offspring are now possible. We suggest a general strategy, based on analysis of tumour DNA, for distinguishing sporadic and familial cases of tumours caused by two hit mechanisms. Application of this strategy suggests that most instances of unilateral vestibular schwannoma which do not fulfil criteria for NF2 represent chance occurrences.

Deletion mapping defines three discrete areas of allelic imbalance on chromosome arm 8p in oral and oropharyngeal squamous cell carcinomas

Deletions on chromosome arm 8p, as defined by allelic imbalance, are a frequent event in many different types of malignant tumors, including those of the head and neck. These regions are thought to harbor tumor suppressor genes. In order to define a high-density deletion map of this chromosomal arm in oral and oropharyngeal squamous cell carcinomas, we have tested for allelic imbalance in 35 such tumors with 22 short tandem-repeat polymorphisms. Overall, 21 (60%) of the 35 tumors showed allelic imbalance at one or more loci on chromosome arm 8p. Interstitial deletions defined three discrete areas of deletion: at 8p23, 8p22, and 8p12-p21. Tumors of TNM stages II-IV showed a significantly higher frequency of allelic imbalance on 8p than did TNM stage I tumors. Our data suggest that there are least three tumor suppressor loci on chromosome arm 8p that may be implicated in oral carcinogenesis. Furthermore, inactivation of such genes may be associated with high-grade tumors.

Allelic imbalance on chromosome 3p in oral dysplastic lesions: an early event in oral carcinogenesis

We have demonstrated previously a loss of constitutional heterozygosity on the short arm of chromosome 3 in approximately 50% of oral squamous cell carcinomas. In the present study, we have investigated 30 oral dysplastic lesions (DLs), presenting clinically as either erythroplakias or leukoplakias with histopathological features of either severe epithelial dysplasia or carcinoma in situ, for LOH on chromosome 3p using 15 microsatellite markers. Thirteen of the 30 LDs (approximately 43%) showed allelic imbalance at one or more loci. The pattern of loss in these lesions defined three noncontiguous regions of interstitial deletions that overlap with those defined for oral squamous cell carcinomas. These data indicate that the alteration of tumor suppressor genes on chromosome 3p is probably an early event in oral carcinogenesis. Additionally, 7 of the 30 DLs showed microsatellite instability. However, the frequency of loci showing microsatellite instability per lesion was low.

Severe Gardner syndrome in families with mutations restricted to a specific region of the APC gene

Familial adenomatous polyposis (FAP) is associated with a number of extraintestinal manifestations, which include osteomas, epidermoid cysts, and desmoid tumors, often referred to as "Gardner syndrome." Recent studies have suggested that some of the phenotypic features of FAP are dependent on the position of the mutation within the APC gene. In particular, the correlation between congenital hypertrophy of the retinal pigment epithelium (CHRPE) and APC genotype indicates that affected families may be divided into distinct groups. We have investigated the association between the dentoosseous features of GS on dental panoramic radiographs (DPRs) and APC genotype in a regional cohort of FAP families. DPRs were performed on 84 affected individuals from 36 families, and the dento-osseous features of FAP were quantified by a weighted scoring system. Significant DPR abnormalities were present in 69% of affected individuals. The APC gene mutation was identified in 27 of these families, and for statistical analysis these were subdivided into three groups. Group 1 comprised 18 affected individuals from seven families with mutations 5' of exon 9; these families (except one) did not express CHRPE. Groups 2 comprised 38 individuals from 16 families with mutations between exon 9 and codon 1444, all of whom expressed CHRPE. Group 3 comprised 11 individuals from four families with mutations 3' of codon 1444, none of whom expressed CHRPE. Families with mutations 3' of codon 1444 had significantly more lesions on DPRs (P < .001) and appeared to have a higher incidence of desmoid tumors. These results suggest that the severity of some of the features of Gardner syndrome may correlate with genotype in FAP.

The dental phenotype in familial adenomatous polyposis: diagnostic application of a weighted scoring system for changes on dental panoramic radiographs

A weighted scoring system (Dental Panoramic Radiograph Score) taking into consideration the nature, extent, and site of osseous and dental changes on dental panoramic radiographs in familial adenomatous polyposis is described. The weighting takes into consideration the incidence of the anomaly in the general population. The reliability of the system was tested by application to 85 people known to be affected by clinical or mutation analysis, 30 people lacking mutation in the adenomatous polyposis gene, and 19 people shown to be at low risk (< 1%) by linkage analysis. Using the highest thresholds, a specificity of 100% and sensitivity of approximately 68% was obtained. If all positive findings were considered as significant, sensitivity was increased to approximately 82% but the specificity was reduced to approximately 88%. Significant DPRS findings were observed at a significantly higher frequency in patients aged over 20 compared to the patients aged 20 and under. Overall, approximately 68% of the affected subjects had significant changes, and approximately 18% had normal appearance on DPR, with the remainder having changes classified as minimal or equivocal.

Deletion mapping on the short arm of chromosome 3 in squamous cell carcinoma of the oral cavity

Loss of heterozygosity indicative of the presence of tumor suppressor genes on chromosome 3p is commonly observed in carcinomas of various tissues. We have examined loss of heterozygosity on chromosome 3p in 27 oral squamous cell carcinomas using 15 highly informative microsatellite polymorphisms and constructed a deletion map of chromosome 3p. Overall, loss of heterozygosity at one or more loci was observed in 14 tumors (approximately 52%). A majority of these tumors (86%) show loss in more than one area. Three distinct regions were identified: 3p13-3p21.1, 3p21.3-3p23, and 3p25. These data suggest a role for at least three tumor suppressor genes on chromosome 3p in oral squamous carcinomas. The regions of deletions overlap with those described for carcinomas of other tissues and parallel those observed in lung carcinomas. This may reflect the common etiology of the two cancers.

Non-penetrance and late appearance of polyps in families with familial adenomatous polyposis

One case of non-penetrance of the familial adenomatous polyposis (FAP) gene at 59 years of age and late onset of polyps on endoscopy and biopsy in this and two other families is described. Screening protocols should include dental screening as well as indirect ophthalmoscopy and endoscopy to detect minimal manifestations of the gene. In the absence of a specific DNA predictive test, bowel screening should continue well beyond 30 years of age.

Tandem duplication within a neurofibromatosis type 1 (NF1) gene exon in a family with features of Watson syndrome and Noonan syndrome

Type 1 neurofibromatosis (NF1), Watson syndrome (WS), and Noonan syndrome (NS) show some overlap in clinical manifestations. In addition, WS has been shown to be linked to markers flanking the NF1 locus and a deletion at the NF1 locus demonstrated in a WS patient. This suggests either that WS and NF1 are allelic or that phenotypes arise from mutations in very closely linked genes. Here we provide evidence for the former by demonstrating a mutation in the NF1 gene in a family with features of both WS and NS. The mutation is an almost perfect in-frame tandem duplication of 42 bases in exon 28 of the NF1 gene. Unlike the mutations previously described in classical NF1, which show a preponderance of null alleles, the mutation in this family would be expected to result in a mutant neurofibromin product.

Complications of the naevoid basal cell carcinoma syndrome: results of a population based study

There are many potential complications which have been reported in association with the naevoid basal cell carcinoma syndrome. We have been able to show the relative frequencies of these problems in a population based study of 84 cases in the north west of England. The major complications of basal cell carcinomas and jaw cysts occur in over 90% of patients by 40 years of age, but may both occur before 10 years of age. Less well described complications are ovarian calcification or fibroma (24%), medulloblastoma (5%), cardiac fibroma (3%), cleft palate (5%), and ophthalmic abnormalities such as squint or cataract (26%). This study more clearly defines the possible complications of the syndrome and gives clearer guidelines for counselling and screening affected and at risk persons.