Loss-of-function mutations in filaggrin gene and malignant melanoma: a case-control study.

BACKGROUND: Loss-of-function mutations in filaggrin gene (FLG) have been suggested to increase the susceptibility of skin malignancies due to reduced levels of epidermal filaggrin and its degradation products, urocanic acid, which may be protective against ultraviolet irradiation. OBJECTIVE: We aimed to investigate the association between FLG mutation status and the occurrence of malignant melanoma (MM) in Danish adults. METHODS: The prevalence of FLG mutations in a sample of MM biopsies was compared with a FLG-genotyped cohort from two general population studies. Pearson's chi-squared and Fisher's exact tests were used to compare the two groups. RESULTS: A total of 867 MM biopsies and 9965 general population controls were genotyped, respectively. In the MM sample, two (0.23%) individuals were homozygous and 80 (9.4%) were heterozygous mutation carriers. In the general population controls, the prevalence of FLG mutations was 18 (0.18%) and 835 (8.4%) for homozygous and heterozygous mutations, respectively. Fisher's exact test and Pearson's chi-squared test yielded non-significant P-values when the groups were compared. CONCLUSION: FLG mutation was not associated with MM in the studied populations. This finding indicates that epidermal deficiency of filaggrin and its degradation products does not influence the risk of MM significantly.

Factor V Leiden is associated with increased sperm count.

STUDY QUESTION: Is the thrombophilia mutation factor V Leiden (FVL) associated with an increased total sperm count? SUMMARY ANSWER: Carriers of FVL have a higher total sperm count than non-FVL-carriers, which could not be explained by genetic linkage or by observations in a FVL-mouse model. WHAT IS KNOWN ALREADY: FVL has a high prevalence in Caucasians despite detrimental health effects. Carriers have been shown to have higher fecundity, which might partly explain this evolutionary paradox. STUDY DESIGN, SIZE, DURATION: We determined FVL status in two cohorts (Dutch, n = 627; Danish, n = 854) of consecutively included men without known causes for spermatogenic failure, and performed an individual patient data meta-analysis of these two cohorts together with one previously published (Dutch, n = 908) cohort. We explored possible biological underpinnings for the relation between sperm count and FVL, by use of a FVL-mouse model and investigations of genetic linkage. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were male partners of subfertile couples (two Dutch cohorts) and young men from the general population (Danish cohort): FVL carrier rate was 4.0%, 4.6% and 7.3%, respectively. There were differences in smoking, abstinence time and age between the cohorts. We corrected for these in the primary analysis, which consisted of a mixed linear effects model, also incorporating unobjectified population differences. In public haplotype data from subjects of European descent, we explored linkage disequilibrium of FVL with all known single nucleotide polymorphisms in a 1.5 MB region around the F5 gene with an R2 cutoff of 0.8. We sequenced exons of four candidate genes hypothesized to be linked to FVL in a subgroup of FVL carriers with extreme sperm count values. The animal studies consisted of never mated 15-18-week-old C57BL/J6 mice heterozygous and homozygous for FVL and wild-type mice. We compared spermatogenesis parameters (normalized internal genitalia weights, epididymis sperm content and sperm motility) between FVL and wild-type mice. MAIN RESULTS AND THE ROLE OF CHANCE: Human FVL carriers have a higher total sperm count than non-carriers, with an adjusted mean difference of 31 × 106 (95%CI 0.2-61.7; P = 0.048). Mice with the FVL mutation do not have increased spermatogenesis as compared to wildtype mice. None of the studied polymorphisms was in linkage disequilibrium, either in the public databases or in a subgroup of FVL carriers with extremely high sperm counts. LIMITATIONS, REASONS FOR CAUTION: The difference in total sperm count would benefit from confirmation in other cohorts. The finding of higher count in carriers was consistent however, with no heterogeneity between the cohorts. The lack of effect of murine FVL might suggest there is no direct causality. The exploratory efforts on genetic linkage do not rule out that the association is a reflection of FVL co-inheritance with a non-studied causative polymorphism. WIDER IMPLICATIONS OF THE FINDINGS: A high sperm count in FVL-carrying males contributes to understanding the high prevalence of this otherwise disadvantageous mutation. The findings might provide directions for future research on male fertility. STUDY FUNDING/COMPETING INTEREST(S): No conflicts of interest. Research was conducted with funding from the Netherlands Organisation for Scientific Research (NWO, VIDI innovative research grant 016.126.364 awarded to S. Middeldorp). The Danish cohort was supported by the Innovation Fund Denmark (InnovationsFonden, grant no. 14-2013-4), The Danish Ministry of Health and the Danish Environmental Protection Agency. TRIAL REGISTRATION NUMBER: Not applicable.

Children with atopic dermatitis and frequent emollient use have increased urinary levels of low-molecular-weight phthalate metabolites and parabens.

BACKGROUND: Parabens may be added to cosmetic and personal care products for preservation purposes. Low-molecular weight (LMW) phthalate diesters function as plasticizers, fixatives or solvents in such products, but may also be found in small quantities as contaminants from plastic containers. OBJECTIVE: To evaluate the association between emollient use, atopic dermatitis and FLG mutations, respectively, with urinary concentrations of phthalate metabolites and parabens in Danish children. METHODS: Eight hundred and forty-five Danish children 4-9 years of age were studied. Urinary concentrations of phthalate metabolites and parabens were determined, and children were genotyped for common FLG loss-of-function mutations. Information about atopic dermatitis and use of emollients was obtained from questionnaires completed by parents. RESULTS: The prevalence of atopic dermatitis was 16.1%. Phthalate metabolite and paraben levels were generally higher in children with frequent use of emollients compared to uncommon users, reaching statistical significance for some LMW phthalates and parabens. While there was no association with common FLG mutations, children with atopic dermatitis had significantly higher urinary levels of one LMW phthalate and two parabens, respectively, when compared to children without atopic dermatitis. CONCLUSION: Emollient use and atopic dermatitis were associated with modestly increased internal LMW phthalate and paraben exposure in 4-9 year old children. It is unknown whether the difference is explained by increased use of the specific emollients that are used to treat pruritic and inflamed skin, and/or whether the impaired skin barrier allows chemicals to penetrate more easily. Moreover, the putative toxicological burden is unknown.

Filaggrin loss-of-function mutations, atopic dermatitis and risk of actinic keratosis: results from two cross-sectional studies.

BACKGROUND: Common loss-of-function mutations in filaggrin gene (FLG) represent a strong genetic risk factor for atopic dermatitis (AD). Homozygous mutation carriers typically display ichthyosis vulgaris (IV) and many have concomitant AD. Previously, homozygous, but not heterozygous, filaggrin gene mutations have been associated with squamous cell carcinomas. OBJECTIVE: The first objective was to examine the association between FLG mutations and actinic keratosis (AK). The second objective was to investigate the occurrence of AK in patients with IV and AD, respectively. METHODS: FLG mutation status in patients with AK was compared with controls from the general population. Furthermore, based on nationwide data from Danish registers, we compared the risk of AK in patients with IV, AD and psoriasis, respectively. RESULTS: The prevalence of homozygous FLG mutations was significantly higher in the AK group (n = 4, 0.8%) in comparison with the control group (n = 18, 0.2%), whereas the prevalence of heterozygous FLG mutations was lower. In hospital registry data, patients with AD exhibited an increased risk of AK than did psoriasis controls (adjusted OR 1.46; [95% CI 1.12-1.90]), whereas no difference in risk was observed between patients with IV and AD. CONCLUSIONS: This study indicates an increased susceptibility to AK in individuals with homozygous, but not heterozygous, FLG mutations and in patients with AD compared to psoriasis. Whether a reduction or absence of epidermal filaggrin could contribute to the susceptibility to AK in patients with IV and AD is unknown and additional research is needed to further explore this relationship.

Epidermal filaggrin deficiency mediates increased systemic T-helper 17 immune response.

BACKGROUND: Cellular T-helper (Th)17 infiltrates dominate skin inflammation in filaggrin-deficient flaky tail (ft/ft) mice, and Th17 cells are found in both the skin and blood of patients with acute atopic dermatitis. However, the potential role of loss-of-function mutations in the filaggrin gene (FLG) for increased peripheral Th17 cells is unclear. OBJECTIVES: To study whether mutations in FLG influence the frequency of peripheral Th17 cells. METHODS: We studied blood samples from six adults with mutations in FLG and five controls without mutations for frequencies of cytokine-producing CD4(+) T cells. We evaluated ft/ft mice and wild-type (WT) control mice for interleukin (IL)-17-producing CD4(+) T cells in naive mice and following 2,4-dinitrofluorobenzene (DNFB) challenge. In addition, the T-cell receptor (TCR) Vß-chain repertoire was analysed by flow cytometry. RESULTS: Human studies showed increased frequency of peripheral Th17 cells in FLG mutation carriers when compared with WT individuals. Mouse studies showed increased frequency of peripheral Th17 cells in adult ft/ft mice but not in 2-week-old ft/ft mice. Moreover, altered TCR Vß-chain repertoire was found in ft/ft mice when compared with WT mice. An increased frequency of CD4(+) Vß10(+) T cells producing IL-17 was found in the spleen of adult ft/ft mice when compared with WT mice. Finally, DNFB challenge induced an increased number of Th17 cells in ft/ft mice compared with WT mice. CONCLUSIONS: Deficiency of filaggrin appeared to be a driver of increased peripheral levels of Th17 cells. This increase must be acquired as peripheral Th17 cells were found in adult ft/ft mice but not in 2-week-old ft/ft mice indicating involvement of exogenous factors.

Randomized clinical trial of prevention of seroma formation after mastectomy by local methylprednisolone injection.

BACKGROUND: Seroma formation, the most prevalent postoperative complication after mastectomy, is an inflammatory process that is potentially preventable via local steroid administration. This study investigated the effect of local steroid administration on seroma formation. METHODS: This was a double-blind randomized placebo-controlled intervention study of a single dose of 80 mg methylprednisolone versus saline on seroma formation after mastectomy. Patients were further classified according to the surgical axillary procedure: mastectomy with sentinel lymph node biopsy (M + SLNB) or mastectomy with level I-II axillary lymph node dissection (M + ALND). Treatments were administered into the wound cavity via the drain orifice following removal of the drain on the first day after surgery. The primary endpoint was seroma formation; secondary endpoints included the frequency of side-effects and complications. RESULTS: A total of 212 women scheduled for mastectomy for primary breast cancer were included. After M + SLNB, 32 (46 per cent) of 69 women developed a seroma in the methylprednisolone group, compared with 52 (78 per cent) of 67 in the saline group (P < 0.001). The mean cumulative seroma volume in the intention-to-treat population for the first 10 and 30 days was significantly lower in the methylprednisolone group (24 ml versus 127 ml in the saline group, and 177 versus 328 ml respectively) (P < 0.001). After M + ALND, similar proportions of patients developed a seroma in the methylprednisolone (35 of 37, 95 per cent) and saline (34 of 36, 94 per cent) groups, and methylprednisolone administration had no significant effect on seroma formation. No differences in infection rate were observed. CONCLUSION: Methylprednisolone administered into the wound cavity on the first day after M + SLNB exerted a highly significant preventive effect against seroma formation during the next 30 days. This effect was not seen in the M + ALND group. Future studies may clarify whether higher or repeated methylprednisolone doses increase the efficacy.

Xerosis is associated with asthma in men independent of atopic dermatitis and filaggrin gene mutations.

BACKGROUND: Epidermal filaggrin deficiency due to common filaggrin gene (FLG) mutations causes xerosis and strongly increases the risk of atopic dermatitis and even asthma. However, it is unknown whether xerosis independent of FLG mutations could also increase the risk of asthma. OBJECTIVE: To evaluate whether generalized xerosis was associated with asthma, independent of atopic dermatitis and common FLG mutations in a cross-sectional study on adult Danes. METHODS: A total of 3396 adults from the general population participated in a health examination. Lung function and serum-specific IgE levels to inhalant allergens were measured and information on xerosis and atopic diseases was obtained by means of a questionnaire. Participants were genotypes for the three most common FLG mutations in Northern Europeans: R501X, 2282del4 and R2447X. RESULTS: Fully adjusted logistic regression analyses showed that asthma (either current or at some point in life) was significantly associated with reporting generalized xerosis (OR 1.32; 95% CI 1.02-1.72). The association was stronger in men (OR 1.79; 95% CI 1.13-2.84) when compared to women (OR 1.18; 95% CI 0.86-1.62). Furthermore, a significant association was observed between xerosis and 'allergic asthma' in men (OR 2.13; 95% CI 1.08-4.19). CONCLUSION: Our findings indicate an association between xerosis and asthma in men independent of atopic dermatitis and FLG mutations. Both facilitated allergen sensitization and secondary degradation of filaggrin following T-helper cell 2 inflammation might be key elements to understanding this relationship.

Filaggrin loss-of-function mutations and incident cancer: a population-based study.

BACKGROUND: Loss-of-function mutations in the filaggrin gene (FLG) could have opposing effects on cancer risk, as mutations are associated with both 10% higher serum vitamin D levels, which may protect against cancer, and with impaired skin barrier function, which may lead to higher cancer susceptibility. OBJECTIVES: To investigate the association of the FLG genotype and cancer types in four population-based cohorts. METHODS: A total of 13,376 individuals were genotyped for FLG mutations. Information on cancer was obtained from the Danish Cancer Registry. Persons with a history of cancer at baseline were excluded from prospective analyses. RESULTS: There were 1339 incident cancers (median follow-up 11·4 years). The hazard ratios (HRs) and 95% confidence intervals (CIs) for FLG mutation carriers vs. wild types were: for any cancer (HR 0·95, 95% CI 0·78-1·16), any cancer excluding nonmelanoma skin cancer (NMSC) (HR 1·05, 95% CI 0·84-1·31), head and neck cancer (HR 1·72, 95% CI 0·71-4·15), colorectal cancer (HR 0·82, 95% CI 0·44-1·52), bronchus and lung cancer (HR 1·34, 95% CI 0·77-2·33), breast cancer (HR 0·58, 95% CI 0·30-1·14), uterine cancer (HR 0·42, 95% CI 0·06-3·10), prostate cancer (HR 1·09, 95% CI 0·61-1·94), urinary cancer (HR 1·30, 95% CI 0·51-3·29), malignant melanoma (HR 1·03, 95% CI 0·41-2·58) and NMSC (HR 0·70, 95% CI 0·47-1·05). Among participants aged over 60 years at baseline, we found statistically significant lower risks of all cancers and NMSC among FLG mutation carriers. CONCLUSIONS: The only significant associations between FLG loss-of-function mutations and cancer were in subgroup analyses.

Skin prick test reactivity to aeroallergens by filaggrin mutation status.

BACKGROUND: Studies have shown that filaggrin gene (FLG) mutations are positively associated with sensitization to aero allergens. We hypothesized that FLG mutations would also have an effect on the mean size of positive skin prick test (SPT) reactions as well as the number of positive reactions. OBJECTIVE: To investigate the effect of FLG mutations on the mean size and the number of positive SPT reactions, as well as the association with positive specific IgE. METHODS: A random sample of 3335 adults from the general population in Denmark was genotyped for the R501X and 2282del4 mutations in the FLG. SPT and specific IgE measurements to common aeroallergens were also performed. RESULTS: FLG mutations did not influence the mean size and number of positive SPT reactions. Also, no association was found between FLG mutations and specific IgE measurements. CONCLUSION: Our findings suggest that FLG mutations alone are insufficient to cause secondary sensitization to allergens. The positive association seen in patients must be explained by a combination of further barrier abnormality caused by dermatitis as well as increased allergen exposure.

Atopic diseases by filaggrin mutations and birth year.

BACKGROUND: The prevalence of atopic disorders has increased in recent years. The pathogenesis is complex with genetic and environmental risk factors. Filaggrin loss-of-function mutations are common and associated with atopic disorders. We investigated whether the prevalence of filaggrin mutations increased in different birth cohorts in adults from the general population in Denmark. METHODS: Cross-sectional questionnaire and filaggrin gene mutation (R501X and 2282del4) data from 3335 18- to 69-year-old adults were available for analyses. RESULTS: The effect of filaggrin mutations on the prevalence of atopic diseases, albeit not statistically significant, depended mostly on birth year for atopic dermatitis (AD). A nonsignificant increase in the prevalence of filaggrin mutations was noted across birth year groups reporting AD, with 12.9% in adults born in 1936-1949 and 19.0% born in 1976-1988. CONCLUSIONS: If confirmed in other populations, the observed increase suggests that mutation carriers have been more susceptible to environmental changes accentuating the rise in AD prevalence.

Filaggrin loss-of-function mutation R501X and 2282del4 carrier status is associated with fissured skin on the hands: results from a cross-sectional population study.

BACKGROUND: Filaggrin metabolites act as osmolytes and are important for skin hydration. Carriers of filaggrin loss-of-function mutations have a higher prevalence of atopic dermatitis and dry skin. There is also evidence to suggest that filaggrin mutations increase the risk of hand eczema in atopic individuals. In our clinic, we have observed a distinct phenotype of hand eczema in patients with filaggrin mutation carrier status, characterized by fissured dermatitis on the dorsal aspect of the hands and with only sparse involvement of the palms including fine scaling. OBJECTIVES: To investigate whether filaggrin loss-of-function mutations are associated with skin fissures on the hands and/or fingers in the general population. METHODS: Participants in a population-based study were questioned about skin symptoms, genotyped for filaggrin mutation, patch tested for nickel allergy and skin prick tested. RESULTS: In an adjusted logistic regression analysis, filaggrin mutation status was significantly associated with fissured skin on the hands and/or fingers in adults (odds ratio 1·93, 95% confidence interval 1·05-3·55) and showed a nearly significant negative interaction with atopic dermatitis (P=0·055), suggesting that the effect was predominantly in subjects without atopic dermatitis. CONCLUSIONS: Filaggrin loss-of-function mutations seem not only to increase the risk of atopic dermatitis and dry skin but also the risk of fissures on the hands and/or fingers in subjects without atopic dermatitis. Prophylactic emollient therapy should be particularly encouraged in filaggrin loss-of-function mutation carriers.

The filaggrin null genotypes R501X and 2282del4 seem not to be associated with psoriasis: results from general population study and meta-analysis.

BACKGROUND: Psoriasis vulgaris could be associated with the filaggrin null genotype since certain known susceptibility loci for psoriasis are shared with susceptibility loci for atopic dermatitis. Furthermore, filaggrin expression is lowered in psoriatic skin lesions but normally expressed in uninvolved skin. So far five relatively small patient-based case-control studies have rejected a possible association between psoriasis and the two most prevalent filaggrin null mutations, 2282del4 and R501X. OBJECTIVES: To reinvestigate a possible association between psoriasis and filaggrin null mutation status by using cross-sectional general population questionnaire data. Also, to perform a meta-analysis including published studies that investigated the relation between filaggrin gene mutations R501X and 2282del4, respectively, and psoriasis vulgaris. METHODS: Between June 2006 and May 2008, a cross-sectional study was performed in the general population in Copenhagen. A random sample of 7931 subjects aged 18-69 years was invited to participate in a general health examination including a questionnaire and 3471 (43.7%) participated. A total of 3335 (96.1%) individuals were filaggrin genotyped for the 2282del4 and R501X mutations. A meta-analysis was undertaken to investigate the relation between filaggrin gene mutations and psoriasis vulgaris. RESULTS: The prevalence of self-reported psoriasis was 6.7% among the 3240 respondents. The prevalence of the R501X and 2282del4 filaggrin null genotypes was 9.3% in subjects who reported psoriasis and 8.0% in subjects who did not report psoriasis (OR = 1.28; 95% CI = 0.74-1.89; P = 0.78). The meta-analysis found no association between the filaggrin null genotypes R501X and 2282del4 and psoriasis (OR = 1.04; 95% CI = 0.81-1.35). CONCLUSIONS: Psoriasis was not associated with the R501X and 2282del4 filaggrin null genotypes in a general population study and in a meta-analysis on published studies.

Individuals who are homozygous for the 2282del4 and R501X filaggrin null mutations do not always develop dermatitis and complete long-term remission is possible.

BACKGROUND: About 8-10% of the general population in Europe carry a null mutation in the filaggrin gene which is associated with early onset of atopic dermatitis as well as persistence into adulthood. No studies have investigated whether individuals with the homozygous filaggrin null genotype always develop dermatitis. OBJECTIVES: The aim of this study was to describe the natural history of individuals with no filaggrin expression. MATERIALS: Three study populations were included: (i) a random sample of 3335 subjects aged 18-69 years from the general population in Copenhagen who underwent general health examination; (ii) a total of 499 patients seen in our dermatitis clinic since 2009 and who were filaggrin genotyped as a part of the routine diagnostic work up; and (iii) a prospective, longitudinal, birth cohort study of 411 children born to mothers with a history of asthma. Filaggrin genotyping was performed for the 2282del4 and R501X mutations. RESULTS: Filaggrin homozygous/compound heterozygous individuals accounted for 0.3% of adults, 3% of dermatitis patients and 0.7% of children. Respectively, one of nine adults and one of three children never experienced dermatitis until now. All hospital patients had atopic dermatitis with onset during (early) childhood. Year-long complete remission was observed in half of patients. CONCLUSIONS: The natural history of individuals with the filaggrin null genotype is fairly good in the sense that they may not develop dermatitis at all, and if they do, they may experience complete remission.

Association between filaggrin null mutations and concomitant atopic dermatitis and contact allergy.

BACKGROUND: The phenotypic traits of people with the filaggrin mutation (FLG) genotype and atopic dermatitis (AD) are still under elucidation, and the association with concomitant AD and contact allergy (CA) has not previously been examined. AIM: To assess FLG status in a subset of patients with AD and a minimum of one positive patch-test reaction. METHODS: In total, 430 people from a hospital population and 3335 people from the general population were tested for FLG mutations by DNA hybridization to paramagnetic polystyrene beads and analysis on a multiplex analysis system. All of the individuals in the hospital population had a minimum of one CA. AD was diagnosed according to the UK Working Party Criteria, (questions-only version). Individuals from the hospital population who had both AD and CA were considered as cases, and comparison of mutation carrier frequency was estimated (χ(2) test) against individuals without AD but with CA from the hospital population, individuals from the general population, and individuals with AD from the general population. RESULTS: The mutation frequency in patients with AD and CA in the hospital population was significantly less than that of people with AD from the general population (OR = 0.54; 95% CI 0.30-0.98). No difference in mutation frequency was found between individuals with and without AD in the hospital population (OR = 1.40; 95% CI 0.70-2.79), or between individuals with AD and CA in the hospital population and in the overall general population (OR = 1.29; 95% CI 0.76-2.20). CONCLUSIONS: The spectrum of observable traits characteristic for the FLG mutation genotype in patients with AD is at present not defined. Our results indicate that the subset of patients with both AD and CA represent a phenotype of AD that is not associated with FLG mutations.

Filaggrin null mutations increase the risk and persistence of hand eczema in subjects with atopic dermatitis: results from a general population study.

BACKGROUND: Hand eczema is prevalent in the general population. It remains unclear whether or not filaggrin gene (FLG) null mutations increase the overall risk of hand eczema or only increase the risk of hand eczema in subjects with atopic dermatitis. OBJECTIVES: To investigate the association between FLG null mutations and hand eczema. METHODS: A random sample of 3335 adults from the general population in Denmark was patch tested, FLG genotyped for R501X and 2282del4 null mutations and questioned about hand eczema. RESULTS: Participants with combined presence of atopic dermatitis and FLG null mutation status had a significantly higher prevalence of hand eczema, an earlier onset of hand eczema and a higher persistence of hand eczema compared with subjects with normal FLG status and absence of atopic dermatitis. Logistic regression analyses revealed positive associations between hand eczema within the past 12 months and FLG null mutation status in participants with a history of atopic dermatitis [odds ratio (OR) 2.98; 95% confidence interval (CI) 1.27-7.01], but not in subjects without atopic dermatitis (OR 0.82; 95% CI 0.41-1.67). CONCLUSIONS: FLG null mutations were significantly associated with hand eczema (< 12 months) in subjects with atopic dermatitis. Combined atopic dermatitis and filaggrin null mutation status was strongly associated with early onset of hand eczema and hand eczema persistence.

The association between null mutations in the filaggrin gene and contact sensitization to nickel and other chemicals in the general population.

BACKGROUND: It was recently shown that filaggrin gene (FLG) null mutations are positively associated with nickel sensitization. We have hypothesized that histidine-rich filaggrin proteins in the epidermis chelate nickel ions and prevent their skin penetration and exposure to Langerhans cells. Furthermore, we have proposed that the low degree of genetic predisposition to nickel sensitization found by a Danish twin study was explained by a high prevalence of ear piercing among participants resulting in 'bypassing' of the filaggrin proteins. OBJECTIVES: To investigate the association between FLG null mutations and (nickel) contact sensitization. METHODS: A random sample of 3335 adults from the general population in Denmark was patch tested and genotyped for R501X and 2282del4 in the FLG gene. RESULTS: The combined carrier frequency of FLG null mutations was 8·1%. Nickel, fragrance and contact sensitization to at least one allergen were not associated with FLG null mutations. A crude analysis on women who did not have ear piercings revealed a positive association between FLG null mutations and nickel sensitization [8·3% vs. 2·4%; odds ratio (OR) 3·71, 95% confidence interval (CI) 0·73-18·96] as well as between FLG null mutations and allergic nickel dermatitis (8·3% vs. 1·3%; OR 6·75, 95% CI 1·17-38·91). FLG mutation status and atopic dermatitis were positively associated with neomycin or ethylenediamine sensitization. CONCLUSIONS: This study suggests that FLG null mutations may be a risk factor for the development of nickel sensitization. However, ear piercing was a much stronger risk factor in our general population and we could therefore identify a positive association only in women without ear piercings. Contact sensitization to specific chemicals is related to treatment exposure.

An aspartic proteinase from human erythrocytes is immunochemically indistinguishable from a non-pepsin, electrophoretically slow moving proteinase from gastric mucosa.

Antiserum raised against an erythrocyte membrane-attached aspartic proteinase precipitates a non-pepsin gastric proteinase. With a monospecific antiserum raised against the non-pepsin gastric proteinase the two enzymes show immunochemical identity. The isoelectric points of both are between 4.5 and 4.6. By SDS-polyacrylamide gel electrophoresis the two proteinases behave the same way. Under non-reducing conditions the main components show molecular weights around 90 000 and after reduction about 58 000. The proteinase may tentatively be classified as cathepsin E.

Seminal pepsinogen C is not identical with, but is very similar to gastric pepsinogen C.

Human seminal pepsinogen C has been purified and compared with gastric pepsinogen C. The two zymogens cannot be distinguished by amino acid compositions and sequences of the first 28 N-terminal amino acid residues are identical. Apparent immunological identity is observed with polyclonal antisera. Monoclonal antibodies toward seminal pepsinogen C have been produced. One is able to recognize a non-carbohydrate antigenic determinant only present in seminal pepsinogen C.