Temporal variation of Staphylococcus aureus clonal complexes in atopic dermatitis: a follow-up study.

BACKGROUND: A strong link between disease severity and Staphylococcus aureus colonization of the skin has been reported in patients with atopic dermatitis (AD). OBJECTIVES: To examine temporal variations in S. aureus colonization and S. aureus CC type in patients with AD, and to investigate links to disease severity, skin barrier properties and filaggrin gene (FLG) mutations. METHODS: This was a follow-up study of a cohort of 101 adult patients with AD recruited from an outpatient clinic. Bacterial swabs were taken at baseline and follow-up from lesional skin, nonlesional skin and the nose. Swabs positive for S. aureus were characterized by spa and the respective clonal complex (CC) type was assigned. Patients were characterized with respect to disease severity [Scoring Atopic Dermatitis (SCORAD)], skin barrier properties [transepidermal water loss (TEWL), pH] and FLG mutations. RESULTS: In total, 63 patients participated in a follow-up visit. Twenty-seven patients (43%) were colonized at both visits, 27 were colonized at only one visit and nine (14%) were not colonized at either visit. Of patients colonized at both visits, 52% remained colonized with the same CC type at follow-up. Change in CC type was related to an increase in SCORAD of 10·7 points; patients who carried the same CC type had a reduction in SCORAD of 4·4 points. Significantly higher skin pH was found in patients colonized at both visits, while change in CC type was not related to TEWL, pH or FLG mutations. CONCLUSIONS: The data indicate that temporal variation in S. aureus CC type is linked to flares of the disease.

Using landscape scenarios to improve local nitrogen management and planning.

Scenario-building is a widely used tool to initiate discussions on future land uses. In scenarios possible futures can be explored and peoples' ideas as well as societal trends can be visualized by the use of maps, pictures and figures. With focus on agricultural nitrogen management, and point of departure in the farmers' decisions-regarding fertilizer inputs, crop rotations, land use, and drainage, landscape scenarios are formulated based on local ideas for future nitrogen management and general prospects for local development. The key research question addressed in this paper is how landscape scenarios can guide farmers to improve nitrogen management in smaller catchments dominated by farming. Participatory modelling was used to develop landscape scenarios, depicting the change of nitrogen emission as a result of changes in landscape management and agricultural practices. In the development of the scenarios we used an ArcMap based tool combining statistical data, experimental knowledge, nitrate leaching modelling and input from local stakeholders on biophysical as well as land use and farm management issues. The scenarios presented are the result of a collaborative planning experiment within the frames of the dNmark research alliance on nitrogen. Three different types of scenarios are presented and discussed and their effects in terms of N reduction are estimated. The three scenarios were called: River valley set-aside, constructed wetlands, and land zonation. All the modelled scenarios are estimated to have a positive effect i.e. a reduction of the level of N leached to the root zone. Based on the experience gathered in the project, the feasibility of using scenarios for future environmental planning in the agricultural landscapes is discussed. Further, this is related to the current discussion in Denmark on geographically targeted nitrogen regulation. It is concluded that the co-creative approach to formulation of scenarios can be an effective way of increasing the knowledge and ownership of possible future solutions, however the cost associated with this planning approach is likely to substantially higher that more traditional planning approaches. Consequently, the estimated transactions costs should be weighed against the expected benefits in terms of more successful implementation.

Confirmation of an IRAK3 polymorphism as a genetic marker predicting response to anti-TNF treatment in rheumatoid arthritis.

Several genetic variants in Toll-like receptor (TLR) and nuclear factor (NF)-κB signalling pathways have been reported associated with responsiveness to tumour necrosis factor inhibitor (anti-TNF) treatment in rheumatoid arthritis (RA). The present study was undertaken to replicate these findings. In a retrospective case-case study including 1007 Danish anti-TNF-treated RA patients, we genotyped 7 previously reported associated single-nucleotide polymorphisms (SNPs) in these pathways. Furthermore, 5 SNPs previously reported by our group were genotyped in a subcohort (N=469). Primary analyses validated the IRAK3 rs11541076 variant as associated (odds ratio (OR)=1.33, 95% confidence interval (CI): 1.00-1.77, P-value=0.047) with a positive treatment response (EULAR (European League Against Rheumatism) good/moderate vs none response at 4±2 months), and found the NLRP3 rs461266 variant associated (OR=0.75, 95% CI: 0.60-0.94, P=0.014) with a negative treatment response. Meta-analyses combining data from previous studies suggested smaller effect sizes of associations between variant alleles of CHUK rs11591741, NFKBIB rs3136645 and rs9403 and a negative treatment response. In conclusion, this study validates rs11541076 in IRAK3, a negative regulator of TLR signalling, as a predictor of anti-TNF treatment response, and suggests true positive associations of previously reported SNPs within genes encoding activators/inhibitors of NF-κB (CHUK, MYD88, NFKBIB, and NLRP3).

Associations between functional polymorphisms and response to biological treatment in Danish patients with psoriasis.

Biological agents including anti-tumor necrosis factor (anti-TNF; adalimumab, infliximab, etanercept) and anti-interleukin-12/13 (IL12/23; ustekinumab) are essential for treatment of patients with severe psoriasis. However, a significant proportion of the patients do not respond to a specific treatment. Pharmacogenetics might be a way to predict treatment response. Using a candidate gene approach, 62 mainly functional single-nucleotide polymorphisms (SNPs) in 44 different genes were evaluated in 478 Danish patients with psoriasis undergoing 376 series of anti-TNF treatment and 230 series of ustekinumab treatment. Associations between genetic variants and treatment outcomes (drug survival and Psoriasis Area Severity Index reduction) were assessed using logistic regression analyses (crude and adjusted for gender, age, psoriatic arthritis and previous treatment). After correction for multiple testing controlling the false discovery rate, six SNPs (IL1B (rs1143623, rs1143627), LY96 (rs11465996), TLR2 (rs11938228, rs4696480) and TLR9 (rs352139)) were associated with response to anti-TNF treatment and 4 SNPs (IL1B (rs1143623, rs1143627), TIRAP (rs8177374) and TLR5 (rs5744174)) were associated with response to ustekinumab treatment (q<0.20). The results suggest that genetic variants related to increased IL-1ß levels may be unfavorable when treating psoriasis with either anti-TNF or ustekinumab, whereas genetic variants related to high interferon-γ levels may be favorable when treating psoriasis with ustekinumab.

Identification of a PVL-negative SCCmec-IVa sublineage of the methicillin-resistant Staphylococcus aureus CC80 lineage: understanding the clonal origin of CA-MRSA.

OBJECTIVES: Community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) isolates belonging to clonal complex 80 (CC80) are recognized as the European CA-MRSA. The prevailing European CA-MRSA clone carries a type IVc staphylococcal cassette chromosome mec (SCCmec) and expresses Panton-Valentine leukocidin (PVL). Recently, a significant increase of PVL-negative CC80 MRSA has been observed in Denmark. The aim of this study was to examine their genetics and epidemiology, and to compare them to the European CA-MRSA clone in order to understand the emergence of PVL-negative CC80 MRSA. METHODS: Phylogenetic analysis of the CC80 S. aureus lineage was conducted from whole-genome sequences of 217 isolates (23 methicillin-susceptible S. aureus and 194 MRSA) from 22 countries. All isolates were further genetically characterized in regard to resistance determinants and PVL carriage, and epidemiologic data were obtained for selected isolates. RESULTS: Phylogenetic analysis revealed the existence of three distinct clades of the CC80 lineage: (a) an methicillin-susceptible S. aureus clade encompassing Sub-Saharan African isolates (n = 13); (b) a derived clade encompassing the European CA-MRSA SCCmec-IVc clone (n = 185); and (c) a novel and genetically distinct clade encompassing MRSA SCCmec-IVa isolates (n = 19). All isolates in the novel clade were PVL negative, but carried remnant parts (8-12 kb) of the PVL-encoding prophage ΦSa2 and were susceptible to fusidic acid and kanamycin/amikacin. Geospatial mapping could link these isolates to regions in the Middle East, Asia and South Pacific. CONCLUSIONS: This study reports the emergence of a novel CC80 CA-MRSA sublineage, showing that the CC80 lineage is more diverse than previously assumed.

Strong and frequent T-cell responses to the minor allergen Phl p 12 in Spanish patients IgE-sensitized to Profilins.

BACKGROUND: Profilins are dominant pan-allergens known to cause cross-sensitization, leading to clinical symptoms such as pollen-food syndrome. This study aimed to determine the T-cell response to Phl p 12 in profilin-sensitized patients, by measuring the prevalence, strength and cross-reactivity to clinically relevant profilins. METHODS: The release of Phl p allergens from pollen was determined by mass spectrometry and immunochemistry. T-cell responses, epitope mapping and cross-reactivity to profilins (Phl p 12, Ole e 2, Bet v 2 and Mal d 4) were measured in vitro using PBMCs from 26 Spanish grass-allergic donors IgE-sensitized to profilin. Cross-reactivity was addressed in vivo using 2 different mouse strains (BALB/c and C3H). RESULTS: Phl p 12 and Phl p 1 are released from pollen simultaneously and in similar amounts. Both T-cell response frequency (17/26 donors) and strength were comparable between Phl p 12 and Phl p 1. T-cell cross-reactivity to other profilins correlated with overall sequence homology, and 2 immunodominant epitope regions of Phl p 12 were identified. Data from mice immunized with Phl p 12 showed that cross-reactivity to Bet v 2 was mediated by conserved epitopes and further influenced by additional genetic factors, likely to be MHC II. CONCLUSION: The strength, prevalence and cross-reactivity of T-cell responses towards Phl p 12 are comparable to the major allergen Phl p 1, which supports the hypothesis that T cells to Phl p 12 can play an important role in development of allergic symptoms, such as those associated with pollen-food syndrome.

Genetically determined high activity of IL-12 and IL-18 in ulcerative colitis and TLR5 in Crohns disease were associated with non-response to anti-TNF therapy.

Anti-tumour necrosis factor-α (TNF-α) is used for treatment of severe cases of inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). However, one-third of the patients do not respond to the treatment. A recent study indicated that genetically determined high activity of pro-inflammatory cytokines, including interleukin-1ß (IL-1ß), IL-6 and interferon gamma (IFN-γ), are associated with non-response to anti-TNF therapy. Using a candidate gene approach, 21 functional single-nucleotide polymorphisms (SNPs) in 14 genes in the Toll-like receptors, the inflammasome and the IFNG pathways were assessed in 482 and 256 prior anti-TNF naïve Danish patients with CD and UC, respectively. The results were analysed using logistic regression (adjusted for age and gender). Eight functional SNPs were associated with anti-TNF response either among patients with CD (TLR5 (rs5744174) and IFNGR2 (rs8126756)), UC (IL12B (rs3212217), IL18 (rs1946518), IFNGR1 (rs2234711), TBX21 (rs17250932) and JAK2 (rs12343867)) or in the combined cohort of patient with CD and UC (IBD) (NLRP3 (rs10754558), IL12B (rs3212217) and IFNGR1 (rs2234711)) (P<0.05). Only the association with heterozygous genotype of IL12B (rs3212217) (OR: 0.24, 95% CI: 0.11-0.53, P=0.008) among patients with UC withstood Bonferroni correction for multiple testing. In conclusion, Our results suggest that SNPs associated with genetically determined high activity of TLR5 among patients with CD and genetically determined high IL-12 and IL-18 levels among patients with UC were associated with non-response. Further studies will evaluate whether these genes may help stratifying patients according to the expected response to anti-TNF treatment.

Staphylococcus aureus colonization in atopic eczema and its association with filaggrin gene mutations.

BACKGROUND: Atopic dermatitis (AD) is a prevalent disease with significant impact on physical health and quality of life. Staphylococcus aureus has been directly correlated to disease severity, and may also be a contributing causal factor in the pathogenesis of AD. OBJECTIVES: The primary aim was to assess differences in S. aureus colonization in patients with AD with and without filaggrin gene mutations. The secondary aim was to assess disease severity in relation to S. aureus colonization. Exploratory analyses were performed to investigate S. aureus genetic lineages in relation to filaggrin gene (FLG) mutations and disease severity. METHODS: Adult patients with AD (n = 101) were included in the study. Bacterial swabs were taken from lesional skin, nonlesional skin and the nose. Swabs positive for S. aureus were characterized by spa and the respective clonal complex (CC) type assigned. Patients were characterized with respect to disease severity (Scoring Atopic Dermatitis) and FLG mutations (n = 88). Fisher's exact test was used to analyse differences in S. aureus colonization in relation to FLG mutations. RESULTS: Of the 101 patients included, 74 (73%) were colonized with S. aureus. Of the colonized patients, 70 (95%) carried only one CC type in all three different sampling sites. In lesional skin, S. aureus was found in 24 of 31 patients with FLG mutations vs. 24 of 54 wild-type patients (P = 0·0004). Staphylococcus aureusCC1 clonal lineage was more prevalent in patients with FLG mutations (n = 10) than in wild-type patients (n = 2) (P = 0·003). No specific bacterial lineage was linked to disease severity. CONCLUSIONS: Increased S. aureus colonization in patients with AD with FLG mutations, and increased prevalence of CC1 in patients with FLG mutations, suggest that host-microbe interactions and clonal differences in S. aureus are important for colonization of AD skin.

Associations between functional polymorphisms in the NFκB signaling pathway and response to anti-TNF treatment in Danish patients with inflammatory bowel disease.

Antitumor necrosis factor-α (TNF-α) is used for treatment of severe cases of inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). However, one-third of the patients do not respond to the treatment. Genetic markers may predict individual response to anti-TNF therapy. Using a candidate gene approach, 39 mainly functional single nucleotide polymorphisms (SNPs) in 26 genes regulating inflammation were assessed in 738 prior anti-TNF-naive Danish patients with IBD. The results were analyzed using logistic regression (crude and adjusted for age, gender and smoking status). Nineteen functional polymorphisms that alter the NFκB-mediated inflammatory response (TLR2 (rs3804099, rs11938228, rs1816702, rs4696480), TLR4 (rs5030728, rs1554973), TLR9 (rs187084, rs352139), LY96 (MD-2) (rs11465996), CD14 (rs2569190), MAP3K14 (NIK) (rs7222094)), TNF-α signaling (TNFA (TNF-α) (rs361525), TNFRSF1A (TNFR1) (rs4149570), TNFAIP3(A20) (rs6927172)) and other cytokines regulated by NFκB (IL1B (rs4848306), IL1RN (rs4251961), IL6 (rs10499563), IL17A (rs2275913), IFNG (rs2430561)) were associated with response to anti-TNF therapy among patients with CD, UC or both CD and UC (P ⩽ 0.05). In conclusion, the results suggest that polymorphisms in genes involved in activating NFκB through the Toll-like receptor (TLR) pathways, genes regulating TNF-α signaling and cytokines regulated by NFκB are important predictors for the response to anti-TNF therapy among patients with IBD. Genetically strong TNF-mediated inflammatory response was associated with beneficial response. In addition, the cytokines IL-1ß, IL-6 and IFN-γ may be potential targets for treating patients with IBD who do not respond to anti-TNF therapy. These findings should be examined in independent cohorts before these results are applied in a clinical setting.

Genetic susceptibility and genotype-phenotype association in 588 Danish children with inflammatory bowel disease.

AIM: To investigate the association between known inflammatory bowel disease (IBD)-associated genetic variants and development of paediatric IBD, and specific clinical sub-phenotypes. MATERIAL AND METHODS: In this case-control study we included IBD patients <18 years of age at diagnosis from the Danish National Patient Registry and healthy children <18 years of age were randomly selected from the Danish Central Office of Civil Registration. The latter had filled out a questionnaire regarding health status, and DNA was obtained from blood samples and the buccal mucosa. Patient files were retrieved and clinical information was extracted. DNA was obtained from Guthrie cards from the Danish National Neonatal Screening Biobank (PKU-biobanken) at Statens Serum Institut and from blood samples. RESULTS: A total of 588 IBD patients (244 Crohn's disease (CD), 318 ulcerative colitis (UC) and 26 IBD-unclassified (IBDU)) and 543 healthy controls were included. We found an association between CD and rs22411880 (ATG16L1, odds ratio (OR)=1.7 [1.1-1.7], p=0.003), rs5743289 (NOD2, OR=1.4 [1.1-1.9], p=0.009) and the paediatric specific rs1250550 (ZMIZ1, OR=0.7 [0.5-0.9], p=0.01). None of the investigated 41 SNPs were associated with disease localisation, medical treatment or surgery after correcting for multiple analyses. CONCLUSION: We found an association between CD and three previously published genetic variants and replicated the association with the paediatric specific ZMIZ1 gene. No Bonferroni corrected significant genotype-phenotype associations were found. For future studies aimed at finding predictors for disease course in (paediatric) IBD, it will be worthwhile to include a combination of genetic, clinical and serological markers.

Risk factors for Staphylococcus aureus nasal colonization in Danish middle-aged and elderly twins.

Staphylococcus aureus is a human commensal bacterium found in the nasal cavity and other body sites. Identifying risk factors for S. aureus nasal carriage is of interest, as nasal carriage is a risk factor for subsequent invasive infection. We recently investigated the influence of host genetics on S. aureus carriage in Danish middle-aged and elderly twins, which indicated no significant heritability that could account for the observed S. aureus carriage. In the present study, we performed a questionnaire-based study of S. aureus colonization on the same cohort of 2,196 Danish middle-aged and elderly twins to identify specific risk factors for S. aureus nasal colonization, including analyzing the paired twins (n = 478) that were discordant for S. aureus colonization. We found associations between risk factors and S. aureus nasal colonization among middle-aged and elderly twins, including age, male gender, psoriasis, and atopic diseases. Also, present living on a farm is clearly associated with S. aureus colonization, while smoking had a borderline statistically significant protective effect.

Human ß-defensin-2 as a marker for disease severity and skin barrier properties in atopic dermatitis.

BACKGROUND: Skin infections related to disrupted antimicrobial defence are a common problem in atopic dermatitis (AD). Altered levels of antimicrobial peptides, including human ß-defensin (hBD)-2, have been reported in AD skin, and a link to impaired barrier function has been suggested. OBJECTIVES: To study hBD-2 in relation to skin barrier function in patients with AD and controls, and to study hBD-2 in relation to disease severity. METHODS: Twenty-five patients with AD and 11 controls were enrolled. hBD-2 peptide concentration was determined in stratum corneum samples collected by a minimally invasive tape-stripping method. Disease severity was assessed by SCORing Atopic Dermatitis (SCORAD), and skin barrier function was evaluated by measurement of transepidermal water loss (TEWL) and skin pH. Patients with AD were characterized according to filaggrin mutations. RESULTS: hBD-2 concentrations in the stratum corneum were found to differ between lesional and nonlesional AD skin and controls, with the highest values in lesional skin (P < 0·001). SCORAD and TEWL were significantly increased in participants with measureable hBD-2 (P < 0·018 and P < 0·007, respectively). Significant correlations between hBD-2 in lesional skin, and TEWL and SCORAD were observed (R = 0·55 and R = 0·44, respectively). No correlations with skin pH were found. hBD-2 was not found to relate to filaggrin mutations. CONCLUSIONS: A significant correlation was found between hBD-2, disturbed skin barrier function and disease severity. The minimally invasive skin sample technique enables evaluation of the stratum corneum and its proteins over time and provides the possibility of relating these findings to treatment, infections and physiological variations.

Rapid detection, differentiation and typing of methicillin-resistant Staphylococcus aureus harbouring either mecA or the new mecA homologue mecA(LGA251).

The recent finding of a new mecA homologue, mecA(LGA251) , with only 70% nucleotide homology to the conventional mecA gene has brought the routine testing for mecA as a confirmatory test for methicillin-resistant Staphylococcus aureus (MRSA) into question. A multiplex PCR was designed to differentiate mecA(LGA251) from the known mecA together with detection of lukF-PV and the spa gene fragments, enabling direct spa typing by sequencing of the PCR amplicons. The PCR analysis and subsequent spa typing were validated on a large collection (n=185) of contemporary MRSA and methicillin-sensitive S. aureus isolates, including 127 isolates carrying mecA(LGA251) . The mecA(LGA251) gene was situated in staphylococcal cassette chromosome mec type XI elements, and sequence variation within a 631-bp fragment of mecA(LGA251) in 79 isolates indicated a very conserved gene sequence. Following a successful validation, the multiplex PCR strategy was implemented in the routine testing of MRSA for national surveillance. Over a 2-month period, among 203 samples tested, 12 new MRSA cases caused by isolates carrying mecA(LGA251) were identified, emphasizing the clinical importance of testing for these new MRSA isolates.

Effects of a 17q21 chromosome gene variant, tobacco smoke and furred pets on infant wheeze.

The first common genetic factor identified for pediatric asthma by genome-wide association is the chromosome 17q21 locus, harbouring the ORMDL3 gene. ORMDL3 is involved in facilitation of endoplasmic reticulum-mediated inflammatory responses, believed to underlie its asthma association. We investigated associations between the rs7216389 polymorphism in the 17q21 locus affecting ORMDL3 expression and the risk for recurrent wheeze and interactions with exposure to tobacco smoke and furred pets during pregnancy and infancy using a birth cohort of 101,042 infants. Rs7216389 was significantly associated with recurrent wheeze risk among 18-month-old infants. There was a 1.35-fold higher risk of recurrent wheeze among homozygous variant allele carriers compared with homozygous wild-type allele carriers. There was significant interaction between rs7216389 and domestic furred pets, with a positive association between pets and wheeze among homozygous wild-type carriers and a negative association among homozygous variant allele carriers. There was no interaction between rs7216389 and tobacco smoke exposure.

Cloning and occurrence of czrC, a gene conferring cadmium and zinc resistance in methicillin-resistant Staphylococcus aureus CC398 isolates.

We recently reported a phenotypic association between reduced susceptibility to zinc and methicillin resistance in Staphylococcus aureus CC398 isolates from Danish swine (F. M. Aarestrup, L. M. Cavaco, and H. Hasman, Vet. Microbiol. 142:455-457, 2009). The aim of this study was to identify the genetic determinant causing zinc resistance in CC398 and examine its prevalence in isolates of animal and human origin. Based on the sequence of the staphylococcal cassette chromosome mec (SCCmec) element from methicillin-resistant S. aureus (MRSA) CC398 strain SO385, a putative metal resistance gene was identified in strain 171 and cloned in S. aureus RN4220. Furthermore, 81 MRSA and 48 methicillin-susceptible S. aureus (MSSA) strains, isolated from pigs (31 and 28) and from humans (50 and 20) in Denmark, were tested for susceptibility to zinc chloride and for the presence of a putative resistance determinant, czrC, by PCR. The cloning of czrC confirmed that the zinc chloride and cadmium acetate MICs for isogenic constructs carrying this gene were increased compared to those for S. aureus RN4220. No difference in susceptibility to sodium arsenate, copper sulfate, or silver nitrate was observed. Seventy-four percent (n = 23) of the animal isolates and 48% (n = 24) of the human MRSA isolates of CC398 were resistant to zinc chloride and positive for czrC. All 48 MSSA strains from both human and pig origins were found to be susceptible to zinc chloride and negative for czrC. Our findings showed that czrC is encoding zinc and cadmium resistance in CC398 MRSA isolates, and that it is widespread both in humans and animals. Thus, resistance to heavy metals such as zinc and cadmium may play a role in the coselection of methicillin resistance in S. aureus.

Infliximab dependency in children with Crohn's disease.

BACKGROUND: Recently, infliximab dependency has been described. AIM: To assess frequency of ID in 82 consecutive Crohn's disease children treated with infliximab 2000-2006 and to describe clinical and genetic predictors of long-term infliximab response. METHODS: A phenotype model of infliximab dependency was used to assess treatment response: 'immediate outcome' (30 days after infliximab start)--complete/partial/no response. 'Long-term outcome': (i) prolonged response: maintenance of complete/partial response; (ii) infliximab dependency: relapse < or = 90 days after intended infliximab cessation requiring repeated infusions to regain complete/partial response or need of infliximab >12 months to sustain response. Polymorphisms TNF-308 A>G, TNF-857 C>T, Casp9 93 C>T, FasL-844 C>T, LTA 252 C>T and CARD15 (R702W, G908R, 1007fs) were analysed. RESULTS: Ninety-four per cent of children obtained complete/partial response. In long-term outcome, 22% maintained prolonged response, 12% had no response, while 66% became infliximab dependent. Perianal disease and no previous surgery were associated with infliximab dependency (OR 5.34, 95% CI: 1.24-22.55; OR 6.7, 95% CI: 1.67-26.61). No association was found with studied polymorphisms. The cumulative probability of surgery 50 months after starting infliximab was 10% in infliximab dependency, 30% in prolonged responders and 70% in nonresponders (P = 0.0002). CONCLUSIONS: Sixty-six per cent of children became infliximab dependent. Perianal disease and no surgery prior to infliximab were associated with infliximab dependency phenotype.

Idiopathic restrictive cardiomyopathy in children is caused by mutations in cardiac sarcomere protein genes.

BACKGROUND: Restrictive cardiomyopathy (RCM) is rare in childhood, but has a grave prognosis. The cause of disease in most cases is unknown. OBJECTIVE: To determine the prevalence of sarcomere protein gene mutations in children with idiopathic RCM. METHODS: Twelve patients (9 female, mean age 5.1 years) with idiopathic RCM referred between 1991 and August 2006 underwent detailed clinical and genetic evaluation. Nine had received cardiac transplants at the time of the study. The entire coding sequences of the genes encoding eight cardiac sarcomere proteins and desmin were screened for mutations. Familial evaluation was performed on first-degree relatives. RESULTS: Four patients (33%) had a family history of cardiomyopathy: RCM (n = 2); dilated cardiomyopathy (n = 1) and left ventricular non-compaction (n = 1). Sarcomere protein gene mutations were identified in four patients (33%): 2 in the cardiac troponin I gene (TNNI3) and 1 each in the troponin T (TNNT2) and alpha-cardiac actin (ACTC) genes. Two were de novo mutations and 3 were new mutations. All mutations occurred in functionally important and conserved regions of the genes. CONCLUSIONS: Sarcomere protein gene mutations are an important cause of idiopathic RCM in childhood. We describe the first mutation in ACTC in familial RCM. The identification of RCM in a child should prompt consideration of sarcomere protein disease as a possible cause and warrants clinical evaluation of the family.