Flemish network on rare connective tissue diseases (CTD): patient pathways in systemic sclerosis. First steps taken

Despite the low prevalence of each rare disease, the total burden is high. Patients with rare diseases encounter numerous barriers, including delayed diagnosis and limited access to high-quality treatments. In order to tackle these challenges, the European Commission launched the European Reference Networks (ERNs), cross-border networks of healthcare providers and patients representatives. In parallel, the aims and structure of these ERNs were translated at the federal and regional levels, resulting in the creation of the Flemish Network of Rare Diseases. In line with the mission of the ERNs and to ensure equal access to care, we describe as first patient pathways for systemic sclerosis (SSc), as a pilot model for other rare connective and musculoskeletal diseases. Consensus was reached on following key messages: 1. Patients with SSc should have multidisciplinary clinical and investigational evaluations in a tertiary reference expert centre at baseline, and subsequently every three to 5 years. Intermediately, a yearly clinical evaluation should be provided in the reference centre, whilst SSc technical evaluations are permissionably executed in a centre that follows SSc-specific clinical practice guidelines. In between, monitoring can take place in secondary care units, under the condition that qualitative examinations and care including interactive multidisciplinary consultations can be provided. 2. Patients with early diffuse cutaneous SSc, (progressive) interstitial lung disease and/or pulmonary arterial hypertension should undergo regular evaluations in specialised tertiary care reference institutions. 3. Monitoring of patients with progressive interstitial lung disease and/or pulmonary (arterial) hypertension will be done in agreement with experts of ERN LUNG.

Search for a genetic cause in children with unilateral isolated microtia and congenital aural atresia

PURPOSE

Microtia describes a spectrum of auricular malformations ranging from mild dysplasia to anotia. A vast majority of microtia patients demonstrate congenital aural atresia (CAA). Isolated microtia has a right ear predominance (58-61%) and is more common in the male sex. Isolated microtia is a multifactorial condition involving genetic and environmental causes. The aim of this study is to describe the phenotype of children with unilateral isolated microtia and CAA, and to search for a common genetic cause trough DNA analysis.

METHODS

Phenotyping included a complete clinical examination. Description on the degree of auricular malformation (Weerda classification-Weerda 1988), assessment for hemifacial microsomia and age-appropriate audiometric testing were documented. Computerized tomography of the temporal bone with 3-D rendering provided a histopathological classification (HEAR classification-Declau et al. 1999). Genetic testing was carried out by single nucleotide polymorphism (SNP) microarray.

RESULTS

Complete data are available for 44 children (50% was younger than 33 days at presentation; 59.1% boys; 72.7% right ear). Type III microtia was present in 28 patients. Type 2b CAA existed in 32 patients. All patients had a normal hearing at the non-affected side. Genome wide deletion duplication analysis using microarray did not reveal any pathological copy number variant (CNV) that could explain the phenotype.

CONCLUSIONS

Type III microtia (peanut-shell type) in combination with a type 2b CAA was the most common phenotype, present in 23 of 44 (52.3%) patients with isolated unilateral microtia. No abnormalities could be found by copy number variant (CNV) analysis. Whole exome sequencing in a larger sample with a similar phenotype may represent a future diagnostic approach.

OP0094 IDENTIFICATION OF NEW AUTOANTIGENS IN PATIENTS WITH SYSTEMIC SCLEROSIS THROUGH IMMUNOPRECIPITATION COMBINED WITH LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

Background

In up to 20% of patients with systemic sclerosis (SSc) none of the established SSc-specific autoantibodies are present [1]. Notwithstanding, in many of these patients high-titer autoantibodies can be detected on the HEp-2 indirect immunofluorescence assay (HEp-2 IIFA) which suggests the presence of an autoantibody to an intracellular protein expressed by the HEp-2 cell line. Immunoprecipitation of unlabeled cell extract followed by gel-free liquid chromatography tandem mass-spectrometry analysis has the potential to identify new autoantigens in an unbiased manner.

Objectives

To identify new autoantigens through immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (IP + LC-MS/MS) in HEp-2 IIFA-positive patients with SSc in whom none of the established SSc-specific autoantibody specificities are present.

Methods

Forty-nine patients from the University Hospitals Leuven that fulfilled the EULAR-ACR 2013 classification criteria for systemic sclerosis or LeRoy and Medsger’s criteria for early systemic sclerosis and who were negative on the EliA CTD Screen (Thermo Fisher Scientific, United States), which includes centromere protein B, topoisomerase I, RNA polymerase III, fibrillarin, PM-Scl and U1 ribonucleoprotein, were identified. Immunoprecipitation was performed by incubation of sera of these patients (1/30 in 300 µl Tris-buffered saline) with Pierce A/G magnetic beads, subsequent cross-linking with bissulfosuccinimidyl suberate (BS3) followed by incubation with nuclear extract of HeLa cells (100-150 µg) overnight at 4°C. The eluted protein was analyzed through liquid chromatography with tandem mass spectrometry. Mass spectrometry data were matched against the Uniprot Homo Sapiens database with the Mascot search engine. Candidate autoantigens were confirmed through immunoprecipitation followed by western blot of the eluate with target-specific polyclonal rabbit antibodies or western blot of recombinant protein incubated with sera of the index patients.

Results

We identified multiple new autoantigens, including the THO complex subunit 1 (THOC1) and other subunits of the THO complex in 3 patients, nuclear valosin-containing protein like-2 (NVL) in 2 patients, nucleolar and coiled-body phosphoprotein 1 (NOLC1) and multiple interacting proteins in 1 patient, probable 28S rRNA (cytosine(4447)-C(5))-methyltransferase (NOP2) in 1 patient, telomeric repeat-binding factor 2 (TERF2) and TERF2-interacting protein (TERF2IP) in 1 patient and regulator of chromosome condensation 1 (RCC1) in 1 patient. The new targets were confirmed through immunoprecipitation-western blot or western blot of recombinant protein incubated with sera (Figure 1). Furthermore, in 10 patients known SSc-associated autoantigens were strongly immunoprecipitated including multiple Th/To subunits in 5 patients, RuvBL1/2 in 2 patients, multiple PM-Scl subunits in 2 patients (who both were negative on the EliA CTD Screen), and fibrillarin in 1 patient (who was also negative on the EliA CTD .).

Figure 1.

Immunoprecipitation-western blot with target-specific rabbit polyclonal antibody (1/500-2000 dilution), numbers corresponding to order of description of patients, HC healthy control. NE nuclear extract. RP recombinant protein WB-RP western blot of recombinant protein incubated with patient’s sera.

Conclusion

Multiple new autoantigens were identified and confirmed in patients with SSc without previously identified autoantibody specificity. Further evaluation of reactivity against the newly identified autoantigens in patients with SSc with known autoantibody specificities and other cohorts is required. IP + LC-MS/MS can identify new and established autoantigens in patients with SSc.

References

[1]Meier FMP, Frommer KW, Dinser R, et al. Update on the profile of the EUSTAR cohort: an analysis of the EULAR Scleroderma Trials and Research group database. Ann Rheum Dis 2012;71:1355–60. doi:10.1136/annrheumdis-2011-200742

Disclosure of Interests

Jean-Baptiste Vulsteke: None declared, Daniel Blockmans: None declared, Petra De Haes: None declared, Steven Vanderschueren: None declared, Patrick Verschueren: None declared, Kristl G Claeys: None declared, Wim Wuyts Grant/research support from: Boehringer-Ingelheim, Galapagos, Roche, Jan Leo Lenaerts: None declared, Ellen De Langhe: None declared, Xavier Bossuyt Consultant of: Inova Diagnostics, Thermo Fisher Scientific.

OP0170 DECLINE IN FORCED VITAL CAPACITY (FVC) IN PATIENTS WITH SYSTEMIC SCLEROSIS-ASSOCIATED INTERSTITIAL LUNG DISEASE (SSC-ILD) WITH AND WITHOUT DYSPNOEA: DATA FROM THE SENSCIS TRIAL

Background:

Some patients with SSc-ILD develop dyspnoea secondary to parenchymal lung disease, while others do not report dyspnoea even when their lung function is impaired. It is unclear whether the presence of dyspnoea is associated with a worse course of SSc-ILD or with response to therapy.

Objectives:

To investigate the rate of decline in FVC in patients with SSc-ILD in the SENSCIS trial in subgroups by patient-reported dyspnoea at baseline.

Methods:

The SENSCIS trial enrolled patients with SSc-ILD with first non-Raynaud symptom within ≤7 years before screening, extent of fibrotic ILD ≥10% on HRCT and FVC ≥40% predicted. Patients were randomised to receive nintedanib or placebo until the last patient reached week 52. In post-hoc analyses, we analysed the rate of decline in FVC (mL/year) over 52 weeks in patients with and without dyspnoea at baseline based on the question about dyspnoea in the St. George’s Respiratory Questionnaire (SGRQ). Patients who reported having shortness of breath “most days a week”, “several days a week” or “a few days a month” (rather than “only with chest infection” or “not at all”) over the last month were considered to have dyspnoea at baseline. A random slope and intercept model was used to assess the rate of decline in FVC (mL/year) and an interaction test was applied to assess potential heterogeneity in the treatment effect of nintedanib between the subgroups.

Results:

Of 576 patients, 69.8% had dyspnoea at baseline. At baseline, in patients with and without dyspnoea, respectively, mean (SD) extent of fibrotic ILD on HRCT was 37.7 (21.7)% and 31.6 (19.4)%; mean (SD) FVC was 71.0 (16.3) and 76.5 (16.8) % predicted; 50.7% and 44.8% were taking mycophenolate; 53.5% and 41.9% were taking corticosteroids. In the placebo group, the rate of decline in FVC (mL/year) was similar in patients with and without dyspnoea at baseline (Figure). The effect of nintedanib versus placebo on reducing the rate of decline in FVC (mL/year) was numerically more pronounced in patients without dyspnoea (difference: 79.8 [95% CI: 9.8, 149.7]) than with dyspnoea (difference: 25.7 [-19.9, 71.3]), but the exploratory interaction p-value did not indicate heterogeneity in the treatment effect between subgroups (p=0.20).

Conclusion:

In the SENSCIS trial, patients with SSc-ILD who had dyspnoea at baseline had a numerically greater extent of fibrotic ILD on HRCT and numerically lower FVC % predicted at baseline. The rate of decline in FVC in the placebo group was similar in patients with and without dyspnoea. Nintedanib had a numerically greater treatment effect in patients without dyspnoea. These data suggest that the presence of dyspnoea should not be used as a criterion for starting nintedanib in patients with SSc-ILD.

Acknowledgements:

The SENSCIS trial was funded by Boehringer Ingelheim. Medical writing support was provided by Fleishman Hillard Fishburn, London, UK. The authors meet criteria for authorship as recommended by the International Committee of Medical Journal Editors (ICMJE).

Disclosure of Interests:

Elizabeth Volkmann Consultant of: Boehringer Ingelheim, Grant/research support from: Corbus and Forbius, Michael Kreuter Speakers bureau: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Grant/research support from: Boehringer Ingelheim and Roche, Anna-Maria Hoffmann-Vold Speakers bureau: Actelion, Boehringer Ingelheim, Lilly, Merck Sharp & Dohme and Roche, Consultant of: Actelion, Arxx Therapeutics, Bayer, Boehringer Ingelheim, Lilly, Medscape, Merck Sharp & Dohme and Roche, Grant/research support from: Boehringer Ingelheim, Marlies Wijsenbeek Speakers bureau: Boehringer Ingelheim (fees paid to institution) and Hoffmann-La Roche (fees paid to institution), Consultant of: Boehringer Ingelheim (fees paid to institution), Bristol-Myers Squibb (fees paid to institution), Galapagos NV (fees paid to institution), Hoffmann-La Roche (fees paid to institution), NeRRe Therapeutics (fees paid to institution), OncoArendi Therapeutics (fees paid to institution), Respivant Sciences (fees paid to institution) and Savara (fees paid to institution), Grant/research support from: Boehringer Ingelheim (fees paid to institution) and Hoffmann-La Roche (fees paid to institution), Vanessa Smith Speakers bureau: Boehringer Ingelheim and Janssen-Cilag NV, Consultant of: Boehringer Ingelheim, Grant/research support from: Belgian Fund for Scientific Research in Rheumatic diseases (FWRO), Boehringer Ingelheim, Janssen-Cilag NV and Research Foundation - Flanders (FWO), Dinesh Khanna Shareholder of: Eicos Sciences, Inc. (less than 5%), Consultant of: Acceleron Pharma, Actelion, AbbVie, Amgen, Bayer, Boehringer Ingelheim, CSL Behring, Corbus, Gilead Sciences, Galapagos NV, Genentech/Roche, GlaxoSmithKline, Horizon Therapeutics, Merck Sharp & Dohme, Mitsubishi Tanabe Pharma, Sanofi-Aventis and United Therapeutics, Grant/research support from: Bayer, Bristol-Myers Squibb, Horizon Therapeutics, Immune Tolerance Network, National Institutes of Health and Pfizer, Employee of: Chief Medical Officer- CiviBioPharma/Eicos Sciences, Inc., Christopher Denton Speakers bureau: Boehringer Ingelheim, Corbus, Janssen, and Mallinckrodt Pharmaceuticals, Consultant of: Acceleron Pharma, Arxx Therapeutics, Bayer, Boehringer Ingelheim, Corbus, CSL Behring, Galapagos NV, GlaxoSmithKline, Horizon Therapeutics, Janssen, Mallinckrodt Pharmaceuticals, Roche, Sanofi and UCB, Grant/research support from: Arxx Therapeutics, GlaxoSmithKline and Servier, Wim Wuyts: None declared, Corinna Miede Employee of: Currently an employee of mainanalytics GmbH, contracted by Boehringer Ingelheim, Margarida Alves Employee of: Currently an employee of Boehringer Ingelheim, Steven Sambevski Employee of: Currently an employee of Boehringer Ingelheim, Yannick Allanore Consultant of: Boehringer Ingelheim, Medsenic, Menarini and Sanofi, Grant/research support from: Alpine Pharmaceuticals

THU0367 INCIDENCE AND PREVALENCE OF SYSTEMIC SCLEROSIS-ASSOCIATED INTERSTITIAL LUNG DISEASE IN FLANDERS: A 12-YEARS COLLABORATIVE MULTICENTER PROSPECTIVE COHORT STUDY

Background:

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is the main cause of death in SSc and accounts for up to 30-35% of SSc-mortality (1-2). All SSc cases, irrespective of the extent of the skin disease, should be evaluated for ILD (3). The epidemiology of SSc-ILD in Belgium is unknown. In literature, the prevalence of ILD in SSc varies between 19% and 52%. However, different criteria were used to diagnose ILD (4). In 2008, Goh et al. proposed a flow diagram to diagnose SSc-ILD based on chest high-resolution CT-scan (HRCT) and pulmonary function tests (PFTs). Their categorization into limited or extensive ILD has prognostic value (5).

Objectives:

To determine the prevalence and incidence rate of SSc-ILD in Flanders.

Methods:

Up to 12-year follow-up data of consecutive SSc patients were obtained by 2 Flemish expert centres (University Hospitals Ghent and Leuven). Patients fulfilling the LeRoy and/or ACR-EULAR classification criteria were included consecutively in the prospective cohort (6). Patients received HRCT at baseline and on indication thereafter, as well as yearly PFT. All HRCTs were centrally analyzed (Ghent) and patients were categorized according to the Goh criteria as without ILD, with limited ILD (limILD) or with extensive ILD (extILD) (5).

Results:

Between 2006 and 2018, 797 SSc patients (557 Ghent/240 Leuven; 22% limited SSc (LSSc)/59% limited cutaneous SSc (LcSSc)/19% diffuse cutaneous SSc (DcSSc)) had baseline HRCT and PFT. The baseline characteristics are depicted in the table. The mean age (SD) was 53 +/-15 years and the majority of patients was female (76%).

272 SSc patients had ILD at baseline, implicating a baseline prevalence of 34% (272/797). The baseline prevalences were 35% and 55% for the LcSSc and DcSSc subgroups respectively. During a median follow-up of 39 months (IQR: 11-79 months), 44 patients were diagnosed with incidental SSc-ILD, resulting in an incidence rate of 21,0/1000 person-years (PY), 95% CI:15,2-28,1. The incidence rates were 21,7/1000 PY, 95%CI: 14,3-31,6 and 43.9/1000PY, 95%CI: 22.7-76.8 for the LcSSc and DcSSc subgroups respectively.

Table.

Baseline characteristics

SSc (n=797)LcSSc (n=470)DcSSc (n=149)age (years) °53+/-1554+/-1554+/-14♂/♀ *193(24%)/604(76%)109(23%)/361(77%)58(39%)/91(61%)Disease Duration (months) #for 718: 22 (5-72)for 443: 25 (5-80)for 145: 16 (7-52)LSSc/LcSSc/DcSSc *178(22%)/470(59%)/149(19%)follow-up (months) #39 (11-79)38.5 (9.75-81)44 (17.5-78)Anti-centromere antibodies§252/538 (47%)163/317 (51%)19/108 (18%)Anti-topoisomeraseI antibodies§119/519 (23%)66/297 (22%)45/112 (40%)ILD at baseline, *272 (34%)163 (35%)82 (55%)LimILD, *230 (29%)139 (30%)67 (45%)ExtILD, *42 (5%)24 (5%)15 (10%)New ILD during follow-up, §44/52527/30712/67

°: mean +/- standard deviation, *: number of patients (percent), #: median (interquartile range), §= number of patients/total number of patients with available data (%)

Conclusion:

In an unselected cohort of SSc patients, a third of the patients has ILD at baseline which is in line with previous prevalence reports. Importantly, this is the first study reporting incidence rates of SSc-ILD.

References:

[1]Steen VD and Medsger TA, Ann Rheum Dis 2007;66:940-4

[2]Elhai M et al. Ann Rheum Dis 2017;76:1897-1905

[3]Smith V et al. RMD Open 2019;4:e000782. doi:10.1136/rmdopen-2018-000782

[4]Bergamasco A et al. Clinical Epidemiology 2019;11:257-73

[5]Goh N et al. Am J Respir Crit Care Med 2008;177:1248-54

[6]van den Hoogen et al. Arthritis Rheumatol 2013;65:2737-47

Disclosure of Interests:

Els Vandecasteele Grant/research support from: my institution has received a research grant from the Research Foundation Flanders FWO), Speakers bureau: my institution has received speaker fees from Actelion, Karin Melsens: None declared, Daniel Blockmans Consultant of: yes, Speakers bureau: yes, Charlotte Carton: None declared, Filip De Keyser: None declared, Ellen De Langhe Consultant of: member of advisory board for Boehringer, Bernard Lauwerys: None declared, Yves Piette: None declared, Amber Vanhaecke: None declared, Koen Verbeke: None declared, Wim Wuyts Grant/research support from: my institution has received a grant from Boehringer Ingelheim and Roche, Consultant of: my institution has received payments for consultancy from Boehringer Ingelheim and Roche, Speakers bureau: my institution has received speaker fees from Boehringer Ingelheim and Roche, Guy Brusselle: None declared, Vanessa Smith Grant/research support from: The affiliated company received grants from Research Foundation - Flanders (FWO), Belgian Fund for Scientific Research in Rheumatic diseases (FWRO), Boehringer Ingelheim Pharma GmbH & Co and Janssen-Cilag NV, Consultant of: Boehringer-Ingelheim Pharma GmbH & Co, Speakers bureau: Actelion Pharmaceuticals Ltd, Boehringer-Ingelheim Pharma GmbH & Co and UCB Biopharma Sprl

Nintedanib in patients with progressive fibrosing interstitial lung diseases-subgroup analyses by interstitial lung disease diagnosis in the INBUILD trial: a randomised, double-blind, placebo-controlled, parallel-group trial

BACKGROUND

The INBUILD trial investigated the efficacy and safety of nintedanib versus placebo in patients with progressive fibrosing interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). We aimed to establish the effects of nintedanib in subgroups based on ILD diagnosis.

METHODS

The INBUILD trial was a randomised, double-blind, placebo-controlled, parallel group trial done at 153 sites in 15 countries. Participants had an investigator-diagnosed fibrosing ILD other than IPF, with chest imaging features of fibrosis of more than 10% extent on high resolution CT (HRCT), forced vital capacity (FVC) of 45% or more predicted, and diffusing capacity of the lung for carbon monoxide (DLco) of at least 30% and less than 80% predicted. Participants fulfilled protocol-defined criteria for ILD progression in the 24 months before screening, despite management considered appropriate in clinical practice for the individual ILD. Participants were randomly assigned 1:1 by means of a pseudo-random number generator to receive nintedanib 150 mg twice daily or placebo for at least 52 weeks. Participants, investigators, and other personnel involved in the trial and analysis were masked to treatment assignment until after database lock. In this subgroup analysis, we assessed the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis, autoimmune ILDs, idiopathic non-specific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, and other ILDs. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02999178.

FINDINGS

Participants were recruited between Feb 23, 2017, and April 27, 2018. Of 663 participants who received at least one dose of nintedanib or placebo, 173 (26%) had chronic hypersensitivity pneumonitis, 170 (26%) an autoimmune ILD, 125 (19%) idiopathic non-specific interstitial pneumonia, 114 (17%) unclassifiable idiopathic interstitial pneumonia, and 81 (12%) other ILDs. The effect of nintedanib versus placebo on reducing the rate of FVC decline (mL/year) was consistent across the five subgroups by ILD diagnosis in the overall population (hypersensitivity pneumonitis 73·1 [95% CI -8·6 to 154·8]; autoimmune ILDs 104·0 [21·1 to 186·9]; idiopathic non-specific interstitial pneumonia 141·6 [46·0 to 237·2]; unclassifiable idiopathic interstitial pneumonia 68·3 [-31·4 to 168·1]; and other ILDs 197·1 [77·6 to 316·7]; p=0·41 for treatment by subgroup by time interaction). Adverse events reported in the subgroups were consistent with those reported in the overall population.

INTERPRETATION

The INBUILD trial was not designed or powered to provide evidence for a benefit of nintedanib in specific diagnostic subgroups. However, its results suggest that nintedanib reduces the rate of ILD progression, as measured by FVC decline, in patients who have a chronic fibrosing ILD and progressive phenotype, irrespective of the underlying ILD diagnosis.

FUNDING

Boehringer Ingelheim.

The inner and outer of our thorax: silicone breast implants and pulmonary alveolar proteinosis

Pulmonary alveolar (phospholipo)proteinosis (PAP) is a rare lung disease, predominantly autoimmune in nature. This case report describes a patient with insidious dyspnoea since 5 years and a milky appearance of her bronchoalveolar fluid, leading to the diagnosis of PAP. The onset of symptoms coincided with an exchange of her silicone breast implants. Giant cell reaction in axillary adenopathies pointed towards silicone leakage. Adjuvants, such as silicone, might boost pre-existing antigen reactions of the immune system, potentially leading to autoimmune phenomena.

A patient with interstitial lung disease secondary to dermatomyositis: a case report and review of the literature

We describe the case of a man with known dermatomyositis who presented with a dry cough and who early after admission rapidly evolved to respiratory insufficiency. Based on pathological and radiological findings, the diagnosis of diffuse alveolar damage was made. Postmortem examination also revealed infection with yeast, Torulopsis glabrata. Polymyositis (PM) and dermatomyositis (DM) are both auto-immune diseases, which are characterised by the presence of auto-antibodies and tissue-inflammation, mainly involving the muscles. Patients with PM/DM may have pulmonary complications, often responsible for higher morbidity and mortality. Interstitial lung disease can present itself in different shapes and forms (bronchiolitis obliterans organising pneumonia, non-specific organising pneumonia, usual interstitial pneumonia, acute interstitial pneumonia) and the diagnosis is made based on the combination of pathological examination and radiological findings.

Treatment strategies for sarcoidosis

Sarcoidosis is a multisystem disorder of unknown cause with a highly variable course. Corticosteroids are considered the standard agent for treatment, however there is no consensus about when and in whom therapy should be initiated, what dose should be given and for how long. There seems to be a limited benefit on chest radiographic findings, forced vital capacity and diffusing capacity. The evidence supporting the disease-modulating effect is limited. Cytotoxic agents are often used as steroid-sparing in patients requiring chronic therapy, however there are only little randomized controlled trials to support their use and side effects are common. Tumour necrosis factor-a is thought to be crucial in the development of the typical granulomas in sarcoidosis. Many case reports and case series suggest that specific therapy targeted against this cytokine is very effective. Despite these promising results, only limited evidence is found in multicenter randomized controlled trials.

KRAS mutation detection and prognostic potential in sporadic colorectal cancer using high-resolution melting analysis

BACKGROUND

The development of targeted therapies has created a pressing clinical need for molecular characterisation of cancers. In this retrospective study, high-resolution melting analysis (HRMA) was validated and implemented for screening of 164 colorectal cancer (CRC) patients to detect KRAS hot-spot mutations and to evaluate its prognostic value. Direct sequencing was used to confirm and characterise HRMA results.

METHODS

After establishing its sensitivity, HRMA was validated on seven cell lines and inter- and intra-variation were analysed. The prognostic value of KRAS mutations in CRC was evaluated using survival analysis.

RESULTS

HRMA revealed abnormal melting patterns in 34.1% CRC samples. Kaplan-Meier survival curves revealed a significantly shorter overall (OS) and disease-free survival (DFS) for CRC patients harbouring a KRAS mutation. In the Cox regression analysis, only when colon and rectal cancer were analysed separately, KRAS mutation was a negative predictor for OS in patients with rectal cancer and DFS in those with stage II colon cancer.

CONCLUSIONS

HRMA was found to be a valid screening method for KRAS mutation detection. The KRAS mutation came forward as a negative predictive factor for OS in patients with rectal cancer and for DFS in stage II colon cancer patients.

A novel DFNB1 deletion allele supports the existence of a distant cis-regulatory region that controls GJB2 and GJB6 expression

Eleven affected members of a large German-American family segregating recessively inherited, congenital, non-syndromic sensorineural hearing loss (SNHL) were found to be homozygous for the common 35delG mutation of GJB2, the gene encoding the gap junction protein Connexin 26. Surprisingly, four additional family members with bilateral profound SNHL carried only a single 35delG mutation. Previously, we demonstrated reduced expression of both GJB2 and GJB6 mRNA from the allele carried in trans with that bearing the 35delG mutation in these four persons. Using array comparative genome hybridization (array CGH), we have now identified on this allele a deletion of 131.4 kb whose proximal breakpoint lies more than 100 kb upstream of the transcriptional start sites of GJB2 and GJB6. This deletion, del(chr13:19,837,344-19,968,698), segregates as a completely penetrant DFNB1 allele in this family. It is not present in 528 persons with SNHL and monoallelic mutation of GJB2 or GJB6, and we have not identified any other candidate pathogenic copy number variation by arrayCGH in a subset of 10 such persons. Characterization of distant GJB2/GJB6 cis-regulatory regions evidenced by this allele may be required to find the 'missing' DFNB1 mutations that are believed to exist.

Minocycline induced eosinophilic pneumonia: case report and review of literature

A 51-year-old woman with eosinophilic pneumonia due to minocycline is described and a review of available literature is added. Until now, only 49 cases have been described, mainly in the Japanese population. Minocycline induced eosinophilic pneumonia is probably underreported and even underdiagnosed. This case highlights the importance of careful history taking, especially the use of drugs. Relatively safe drugs (like minocycline) can cause serious adverse events. On presentation, the disease mimics an infectious pneumonia. Peripheral eosinophilia can occur but isn't obligatory. A bronchoalveolar lavage may provide the first (and sometimes only) sign of eosinophilic lung disease. Withdrawal of minocycline is often enough although sometimes corticosteroids are needed. In general, prognosis is good when the diagnosis is made on time.

Proximal chromosome 11p contiguous gene deletion syndrome phenotype: case report and review of the literature

The proximal chromosome 11p contiguous gene deletion syndrome (P11pDS), also known as Potocki-Shaffer syndrome (PSS) or DEFECT 11 (OMIM 601224), is a disorder associated with foramina parietalia permagna and multiple osteochondroma (exostoses). Additional features include mental retardation, craniofacial anomalies, seizures and genitourinary abnormalities. Here, clinico-pathological findings of a unique patient with all of these features and, additionally, enlarged ventricles, hypertrophic obstructive cardiomyopathy and adipositas are described. The brain showed malformative lesions with hallmarks of disturbed bulk growth including micrencephaly, periventricular nodular heterotopias and focal cortical dysplasia in the nodulus of the cerebellar vermis. In addition, symmetric foci with vacuolation of the underlying neuropil, intermingled macrophages and large bizarre, partially vacuolated, reactive astrocytes were found. The proximal short arm of chromosome 11 harbors several candidate genes that could explain the patient's signs and symptoms including ALX4 and EXT2, which are always present in the interstitial deletion of the short arm of chromosome 11 in PSS. In addition, MYBPC3 would be a good candidate for the hypertrophic cardiomyopathy. Furthermore, adipositas might be related to the MAPK8IP1 gene. To the best of our knowledge, the present patient is the oldest one so far described with PSS phenotype and the only case that has undergone detailed neuropathological investigation.

Identification and molecular characterization of a novel splice-site mutation (G1205C) in the SQSTM1 gene causing Paget's disease of bone in an extended American family

Paget's disease of bone (PDB) is a common late-onset bone disorder characterized by focal areas of abnormal bone remodeling. Positional cloning efforts resulted in the identification of seven genetic loci (PDB1-7) with putative involvement in the pathogenesis of PDB. Meanwhile, the PDB-causing gene from the PDB3 region on chromosome 5q35 has been identified as the SQSTM1 gene. All mutations identified in this gene so far are located in or close to the ubiquitin-associated (UBA) domain of the protein. In 2001, we reported genotyping results of genetic markers located in the PDB3 region in an extended American family, indicating the involvement of the PDB3 locus. Here, we report the identification of a novel mutation (G1205C) in the SQSTM1 gene in this family. The G1205C mutation is located in the splice donor site of intron 7 and reverse-transcription polymerase chain reaction experiments showed that the presence of the C allele results in the production of two abnormal mRNA transcripts. Translation of the first transcript would result in a protein that lacks amino acids 351-388, including 26 amino acids of the second PEST domain in addition to two amino acids of the UBA domain. The second mutant mRNA transcript could result in a truncated protein (390X) that lacks almost the complete UBA domain. PDB mutations that disrupt the function of the PEST domain of SQSTM1 have not been reported before, so probably the pathogenic effect of both transcripts resides in the disruption of the ubiquitin-binding properties of the protein.

An optimized DHPLC protocol for molecular testing of the EXT1 and EXT2 genes in hereditary multiple osteochondromas

Hereditary multiple osteochondromas (MO) is an autosomal dominant bone disorder characterized by the presence of bony outgrowths (osteochondromas or exostoses) on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes, which encode glycosyltransferases implicated in heparan sulfate biosynthesis. Standard mutation analysis performed by sequencing analysis of all coding exons of the EXT1 and EXT2 genes reveals a mutation in approximately 80% of the MO patients. We have now optimized and validated a denaturing high-performance liquid chromatography (DHPLC)-based protocol for screening of all EXT1- and EXT2-coding exons in a set of 49 MO patients with an EXT1 or EXT2 mutation. Under the optimized DHPLC conditions, all mutations were detected. These include 20 previously described mutations and 29 new mutations - 20 new EXT1 and nine new EXT2 mutations. The protocol described here, therefore, provides a sensitive and cost-sparing alternative for direct sequencing analysis of the MO-causing genes.

Adams-Oliver syndrome: clinical description of a four-generation family and exclusion of five candidate genes

We present a Belgian Adams-Oliver syndrome (AOS) family with 10 affected individuals over four generations, of which six were available for this study. Clinical symptoms observed in these patients were very variable as previously reported in other families and included large areas of alopecia on the vertex of the skull and serious limb reduction defects with agenesis of all toes of one foot. To identify the disease-causing gene, we sequenced the MSX1, CART1, P63 (P73L), RUNX2, and HOXD13 genes in this family and nine previously reported families, but no disease-causing mutations were found. Further investigation is ongoing in these families in order to identify the genetic cause of AOS.

Multiplex ligation-dependent probe amplification to detect subtelomeric rearrangements in routine diagnostics

Subtelomeric rearrangements are believed to be responsible for 5-7% of idiopathic mental retardation cases. Due to the relative complexity and high cost of the screening methods used till now, only preselected patient populations including mostly the more severely affected cases have been screened. Recently, multiplex ligation-dependent probe amplification (MLPA) has been adapted for use in subtelomeric screening, and we have incorporated this technique into routine diagnostics of our laboratory. Since the evaluation of MLPA as a screening method, we tested 275 unselected patients with idiopathic mental retardation and detected 12 possible subtelomeric aberrations: a der(11)t(11;20)(qter;qter), a 19pter duplication, a der(18)t(18;10)(qter; pter), a 15qter deletion, a 8pter deletion, a 6qter deletion, a der(X)t(X;1)(pter;qter), a der(X)t(X;3)(pter;pter), a 5qter duplication, a 3pter deletion, and two 3qter duplications. The patients can be subdivided into two groups: the first containing de novo rearrangements that are likely related to the clinical presentation of the patient and the second including aberrations also present in one of the parents that may or may not be causative of the mental retardation. In our patient cohort, five (1.8%) subtelomeric rearrangements were de novo, three (1.1%) rearrangements were familial and suggestively disease causing, and four (1.5%) were possible polymorphisms. This high frequency of subtelomeric abnormalities detected in an unselected population warrants further investigation about the feasibility of routine screening for subtelomeric aberrations in mentally retarded patients.

Clinical, cytogenetic, and molecular characterization of a patient with a de novo interstitial 22q12 duplication

We report a 19-year-old woman with minor craniofacial anomalies, mild mental retardation, and foramina parietalia permagna (FPP) (OMIM 168500). Cytogenetic analysis showed a de novo interstitial chromosome 22 long arm duplication. FISH with a panel of chromosome 22q12-q13 bands-specific BAC clones refined the cytogenetic investigation, and restricted the duplicated segment to the q12 region. Mutation analysis of FPP genes identified an insertion mutation in the ALX4 gene (344insC) in the proband and her father with loss of function of the gene. The patient's phenotype is considered in the light of the results of the cytogenetic, FISH, and molecular investigations, and her features are compared with those of other patients with similar duplications. Finally, variable phenotypic findings due to different 22q duplicated chromosomal segments are discussed. Our report indicates that 22q12 interstitial duplications are associated with craniofacial anomalies and mild mental retardation, while life threatening malformations are usually not present. Although these phenotypic changes are common and non-specific, molecular study of our patient established more precise relationships between clinical findings and 22q duplicated region(s). This approach fosters better counseling of the families of patients with newly diagnosed, similar duplications.

Variability of fecal pancreatic elastase measurements in cystic fibrosis patients

BACKGROUND

the fecal pancreatic elastase-1 (EL-1) test is a new non-invasive test for pancreatic function. The aim of the study was to evaluate the intra-patient variability of the fecal EL-1 test in a cystic fibrosis (CF) population.

METHODS

26 CF patients were recruited. Mean patient (S.D.) age was 13.7 years (5.39). Nineteen patients had classical pancreatic insufficiency (PI) based on a clinical syndrome of malabsorption plus steatorrhea on a 72 h fecal fat balance. They were all treated with enzyme supplements. Four patients had classical pancreatic sufficiency (PS): no symptoms of malabsorption, no steatorrhea on a 72 h fecal fat balance, no enzyme treatment. Two patients had symptoms suggestive of PI but had a normal 72 h fecal fat balance: (doubtful pancreatic status (PD)). The CF patients were asked to collect stool samples on 7 consecutive days. EL-1 content in the samples was measured in duplicate. A cut-off of 200 microgEL-1/g stool was used for diagnosing PI.

RESULTS

mean intra-assay variability was 4.06%. All PI patients had EL-1 levels below detection limit. For the PS group maximal intra-patient variability was 35%, one stool sample EL-1 level was below the 200-microg cut-off. In the PD group the maximal intra-patient variability was 37% and EL-1 levels were inconclusive for the diagnosis of PI in both patients.

CONCLUSIONS

the EL-1 test can be used for diagnosing severe PI in CF patients with overt clinical symptoms of malabsorption. However, in CF patients where the clinical picture is less clear the EL-1 test may be inconclusive due to significant intra-patient variability.

Molecular analysis of the putative tumour-suppressor gene EXTL1 in neuroblastoma patients and cell lines

Although neuroblastoma is the most common extracranial solid tumour of childhood, little is known about its aetiology. Together with MYCN amplification and chromosome 17q gain, chromosome 1p deletion is one of the most frequently occurring genetic abnormalities in neuroblastoma. Based upon mapping of deletion breakpoints, putative tumour suppressor gene loci have been assigned to the distal part of the short arm of chromosome 1. Recently, the EXTL1 gene was suggested as a candidate neuroblastoma-suppressor gene and to evaluate this hypothesis, we performed 1p deletion analysis and mutation screening of the EXTL1-coding region on DNA from 22 primary neuroblastomas and 21 neuroblastoma cell lines. Deletions of the chromosome region 1p36.1, including the EXTL1 gene, were detected in several neuroblastoma cell lines and primary tumours. EXTL1 mutation screening resulted in the detection of one unclassified variant (Ser28Cys) but could not provide additional evidence of EXTL1 being involved in the aetiology of neuroblastoma.

Identification of a 52 kb deletion downstream of the SOST gene in patients with van Buchem disease

Van Buchem disease is an autosomal recessive skeletal dysplasia characterised by generalised bone overgrowth, predominantly in the skull and mandible. Clinical complications including facial nerve palsy, optic atrophy, and impaired hearing occur in most patients. These features are very similar to those of sclerosteosis and the two conditions are only differentiated by the hand malformations and the tall stature appearing in sclerosteosis. Using an extended Dutch inbred van Buchem family and two inbred sclerosteosis families, we mapped both disease genes to the same region on chromosome 17q12-q21, supporting the hypothesis that van Buchem disease and sclerosteosis are caused by mutations in the same gene. In a previous study, we positionally cloned a novel gene, called SOST, from the linkage interval and identified three different, homozygous mutations in the SOST gene in sclerosteosis patients leading to loss of function of the underlying protein. The present study focuses on the identification of a 52 kb deletion in all patients from the van Buchem family. The deletion, which results from a homologous recombination between Alu sequences, starts approximately 35 kb downstream of the SOST gene. Since no evidence was found for the presence of a gene within the deleted region, we hypothesise that the presence of the deletion leads to a down regulation of the transcription of the SOST gene by a cis regulatory action or a position effect.

[From gene to disease; hereditary multiple exostoses]

Hereditary multiple exostoses is an autosomal dominant disorder characterised by the presence of multiple osteochondromas, resulting in a variety of skeletal deformities. It is a genetically heterogeneous condition for which two genes, EXT1 and EXT2, have been isolated. The EXT1 gene, located at 8q24, has been shown to harbour mutations in 44-66% of the hereditary multiple exostoses-families. Mutations in the EXT2 gene, located at 11p11-p12, are detected in about 30% of the families. Additional linkage to chromosome 19p suggests the existence of an EXT3 gene. EXT1 has been shown to act as a tumour suppressor gene in hereditary multiple exostoses, resulting in osteochondroma formation when both copies of EXT1 are lost. Diagnostic germ-line mutation analysis is operative in the Clinical Genetic Center Leiden, the Netherlands.

Hereditary multiple exostoses: from genetics to clinical syndrome and complications

OBJECTIVE

To give an overview of genetic, clinical and radiological aspects in two families over four generations with known hereditary multiple exostoses (HME).

METHODS AND MATERIAL

After linkage analysis in both families to localize the defective gene, mutation analysis was performed in these genes to identify the underlying mutation. In the 31 affected individuals, location, number and morphology and evolution of exostosis, evolution of remodeling defects at the metaphysis, and the extent of possible complications were evaluated on clinical and imaging (plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI)) data over a lifetime period.

RESULTS AND CONCLUSIONS

Both families demonstrate the gene defect in the same EXT-2 gene locus on chromosome 11p. Exostoses are preferentially located in the lower extremity (hip, knee and lower leg), humerus, and forearm. Any other bone may be involved, except for the calvaria of the skull and the mandible. Exostoses are rather sessile than pedunculated. Exostosis is rarely present at birth but develops gradually and may persist to grow slowly after closure of the growth plates. Preferential expression of the remodeling defect was seen in the hip, distal femur (trumpet-shaped metaphysis) and forearm (shortening of the ulna with secondary bowing of the radius and development of a pseudo-Madelung deformity). These radiological manifestations start at the age of 4-5 years and become more obvious as the enchondral bone formation progresses with age. Reported complications in these families consist of local entrapment phenomenons (vessel, tendon, nerve), frictional bursitis, and sarcomatous transformation. MRI was able to suggest these complications and is the imaging technique of choice in the evaluation of symptomatic exostoses.

A novel deletion mutation of the EXT2 gene in a large Chinese pedigree with hereditary multiple exostosis

Hereditary multiple exostoses (EXT) is an autosomal dominant disease characterized by the formation of cartilage-capped prominences (exostoses) that develop from the juxta-epiphyseal regions of the long bones. 3 genes are known to be involved in the formation of exostoses. Among them, EXT1 and EXT2, which encode enzymes that catalyse the biosynthesis of heparan sulfate, an important component of the extracellular matrix, are responsible for over 70% of the EXT cases. A large Chinese family with hereditary multiple exostoses has been analysed and the disease-causing mutation has been found. Blood samples were obtained from 69 family members, including 23 affected individuals. The EXT phenotype was shown to be linked to the EXT2 gene by using 2-point linkage analysis. After polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis and DNA sequencing, a previously unreported deletion of a G in exon 3 of EXT2 gene was observed. This deletion co-segregated with the disease phenotype, suggesting that it is the disease-causing mutation in this family. Furthermore, in at least 4 members chondrosarcoma occurred after either an operation or injury of the exostosis and 3 of them died of the malignancy in the family. Whether the operation or injury was responsible for the malignant transformation still needs further study.

Mechanisms of interleukin 1beta-induced human airway smooth muscle hyporesponsiveness to histamine. Involvement of p38 MAPK NF-kappaB

We have investigated the effect of IL-1beta on histamine H(1)-receptor (H(1)R)-mediated inositol phosphate (IP) accumulation in human airway smooth muscle cells (HASMC) and on histamine-induced contraction of human bronchial rings. Stimulation of HASMC for 24 h with IL-1beta resulted in significant loss of histamine-induced IP formation, which was associated with a reduction of histamine- induced contraction of IL-1beta-treated human bronchial rings. An inhibitor of NF-kappaB activation, pyrrolidine dithiocarbamate, and a p38 MAPK inhibitor, blocked the IL-1beta-induced H(1)R desensitization, whereas anisomycin, an SAPK/JNK and p38 MAPK activator, mimicked the effect of IL-1beta. IL-1beta has been demonstrated to induce cox-2 expression and PGE(2) synthesis. In our study, indomethacin a cox antagonist, completely inhibited the effect of IL-1beta on H(1)R, whereas exogenously added PGE(2) was able to desensitize H(1)R. Furthermore, H-89, a selective PKA inhibitor, antagonized the effect of IL-1beta. Here, we have demonstrated that IL-1beta desensitizes H(1)R, which involves the activation of p38 MAPK and NF-kappaB, leading to the expression of cox-2 and the synthesis of PGE(2). PGE(2) increases intracellular cAMP resulting in PKA activation, which phosphorylates and functionally uncouples H(1)R. Our results suggest that IL-1beta protects airway smooth muscle against histamine-induced contractile responses and that bronchial hyperreactivity to histamine is not associated with proinflammatory cytokine-induced enhancement in H(1)R signaling.

Increased bone density in sclerosteosis is due to the deficiency of a novel secreted protein (SOST)

Sclerosteosis is a progressive sclerosing bone dysplasia with an autosomal recessive mode of inheritance. Radiologically, it is characterized by a generalized hyperostosis and sclerosis leading to a markedly thickened and sclerotic skull, with mandible, ribs, clavicles and all long bones also being affected. Due to narrowing of the foramina of the cranial nerves, facial nerve palsy, hearing loss and atrophy of the optic nerves can occur. Sclerosteosis is clinically and radiologically very similar to van Buchem disease, mainly differentiated by hand malformations and a large stature in sclerosteosis patients. By linkage analysis in one extended van Buchem family and two consanguineous sclerosteosis families we previously mapped both disease genes to the same chromosomal 17q12-q21 region, supporting the hypothesis that both conditions are caused by mutations in the same gene. After reducing the disease critical region to approximately 1 Mb, we used the positional cloning strategy to identify the SOST gene, which is mutated in sclerosteosis patients. This new gene encodes a protein with a signal peptide for secretion and a cysteine-knot motif. Two nonsense mutations and one splice site mutation were identified in sclerosteosis patients, but no mutations were found in a fourth sclerosteosis patient nor in the patients from the van Buchem family. As the three disease-causing mutations lead to loss of function of the SOST protein resulting in the formation of massive amounts of normal bone throughout life, the physiological role of SOST is most likely the suppression of bone formation. Therefore, this gene might become an important tool in the development of therapeutic strategies for osteoporosis.

Evaluation of the role of RANK and OPG genes in Paget's disease of bone

Paget's disease of bone (PDB) is one of the most common bone disorders in the western world. PDB is characterized by focal areas of increased osteoclastic bone resorption and bone formation, which leads to the formation of poorly structured bone. These abnormalities of bone turnover and structure predispose affected individuals to various complications including bone pain, deformity, pathological fracture, and an increased risk of osteosarcoma. One of the main mechanisms of osteoclast formation and activation involves the receptor activator of nuclear factor -kappaB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) pathway, where binding of RANKL to RANK results in the differentiation of osteoclast precursors. OPG, on the other hand, acts as an inhibitor of osteoclastogenesis by serving as a decoy receptor for RANKL. Recently, mutations in the RANK gene have been shown to cause familial expansile osteolysis, a rare bone disorder showing great similarity to PDB. We performed mutation analysis in the RANK and OPG genes in 28 PDB patients to investigate whether mutations in these genes could be responsible for PDB. Our data suggest that RANK is not directly involved in PDB in our set of patients, as no mutations in the RANK coding region could be identified and allele frequencies of RANK polymorphisms did not differ in PDB patients as compared with the random population. Also, in the OPG gene, we could not detect PDB-causing mutations. However, of the several polymorphisms identified, one (400 + 4 C/T in intron 2), showed a statistically significant increased frequency for the C allele in PDB patients, suggesting that individuals harboring this allele may be more susceptible for developing PDB.

The ALX4 homeobox gene is mutated in patients with ossification defects of the skull (foramina parietalia permagna, OMIM 168500)

Foramina parietalia permagna (FPP) (OMIM 168500) is caused by ossification defects in the parietal bones. Recently, it was shown that loss of function mutations in the MSX2 homeobox gene on chromosome 5 are responsible for the presence of these lesions in some FPP patients. However, the absence of MSX2 mutations in some of the FPP patients analysed and the presence of FPP associated with chromosome 11p deletions in DEFECT 11 (OMIM 601224) patients or associated with Saethre-Chotzen syndrome suggests genetic heterogeneity for this disorder. Starting from a BAC/P1/cosmid contig of the DEFECT 11 region on chromosome 11, we have now isolated the ALX4 gene, a previously unidentified member of the ALX homeobox gene family in humans. Mutation analysis of the ALX4 gene in three unrelated FPP families without the MSX2 mutation identified mutations in two families, indicating that mutations in ALX4 could be responsible for these skull defects and suggesting further genetic heterogeneity of FPP.

Characterization and genomic localization of the mouse Extl2 gene

Human EXTL2 is an alpha1,4-N-acetylhexosaminyltransferase involved in the biosynthesis of heparin/heparan sulfate. We have cloned and characterized the mouse homolog of this gene. Mouse Extl2 encodes a 330 amino acid protein that is 87% identical to its human counterpart. Expression analysis showed that Extl2 is ubiquitously expressed in adult mouse tissues and that the Extl2 transcript is already present in early stages of embryonic development. Determination of the genomic structure revealed that the Extl2 gene spans five exons within a 10-kb region and that the genomic organization between mouse and man is well preserved, with conservation of the number and position of all five exons. By radiation hybrid analysis, Extl2 was mapped to mouse chromosome 3, in a region homologous to the human EXTL2 region on chromosome 1.

Molecular basis of multiple exostoses: mutations in the EXT1 and EXT2 genes

Hereditary multiple exostoses (EXT) is an autosomal dominant disorder characterized by the formation of exostoses, which are cartilage-capped bony protuberances mainly located on long bones. Two genes, EXT1 and EXT2, and at least one other unidentified gene, are known to be involved in the formation of exostoses. To date, 49 different EXT1 and 25 different EXT2 mutations have been found in EXT patients, and there is evidence that mutations in these two genes are responsible for over 70% of the EXT cases. Among the 49 EXT1 mutations there are 9 nonsense, 21 frameshift, and 5 splice site mutations; 2 in-frame deletions of 1 and 5 amino acids respectively; and 12 missense mutations. For EXT2, 8 nonsense, 11 frameshift, 3 splice site and 3 missense mutations are described. The majority of these mutations are mutations causing loss of function, which is consistent with the presumed tumor suppressor function of the EXT genes.

Identification of mutations in the MSX2 homeobox gene in families affected with foramina parietalia permagna

Foramina parietalia permagna (FPP) is an autosomal dominant condition characterized by cranial defects of the parietal bones. It can be present as an isolated feature, but it is also one of the characteristics of a contiguous gene syndrome associated with deletions on chromosome 11p11-p12. One of the proteins known to be involved in skull development is the MSX2 homeobox protein. Previously, MSX2 has been shown to be mutated in patients suffering from Boston type craniosynostosis. We have now analyzed the MSX2 gene in five families affected with FPP. An intragenic microsatellite marker did not reveal any recombination and a cumulated LOD score of +3.2 at theta = 0 was obtained. Sequence analysis further showed that in four out of five families an MSX2 mutation was responsible for the skull defect. Moreover, it appears that FPP is caused by haplo-insufficiency of the MSX2 gene. This implies that Boston type craniosynostosis and FPP are allelic variants of the same gene, with FPP caused by loss of MSX2 function and craniosynostosis Boston type due to gain of MSX2 function.

Organization of the ribosomal operon 165-235 gene spacer region in representatives of Neisseria gonorrhoeae

Ribosomal rRNA gene fragments (rDNA) encompassing part of the 16S rDNA, the 16S-23S rDNA spacer region and part of the 23S rDNA of 229 Neisseria gonorrhoeae strains were enzymatically amplified using conserved primers. The fragments of approximately 1200 bp were subjected to restriction analysis with HinfI. This revealed 13 patterns (patterns I-XIII) of which patterns I (78 strains), II (32 strains), III (38 strains) and IV (56 strains) were the most abundant, comprising 89.1% of the strains. The obtained restriction patterns consisted of 3 to 8 bands, ranging in size from 32 to 854 bp. The sum of the obtained bands was about 1200 bp for patterns I, II, III, IV, V, IX, and XIII. However, for patterns VI, VII, VIII, X, XI and XII, the sum of the bands well exceeded the estimated size of approximately 1200 bp. We demonstrated that this results from sequence divergence in the 4 rRNA operons, present in the genome of N. gonorrhoeae, giving rise to patterns that are a combination of several other patterns.