Evolution of genome diagnostics in epidermolysis bullosa: Unveiling the power of next-generation sequencing.

BACKGROUND: Genome diagnostics is considered gold standard diagnostics for epidermolysis bullosa (EB), a phenotypically and genetically heterogeneous group of rare disorders characterized by blistering and wounding of mucocutaneous tissues. EB is caused by pathogenic variants in genes encoding proteins of the dermo-epidermal junction. Accurate genetic diagnosis of EB is crucial for prognostication, counselling and precision-medicine. Genome diagnostics for EB started in 1991 with the introduction of Sanger sequencing (SS), analysing one gene at a time. In 2013, SS was superseded by next-generation sequencing (NGS), that allow for high-throughput sequencing of multiple genes in parallel. Several studies have shown a beneficial role for NGS in EB diagnostics, but its true benefit has not been quantified. OBJECTIVES: To determine the benefit of NGS in EB by systematically evaluating the performance of different genome diagnostics used over time based on robust data from the Dutch EB Registry. METHODS: The diagnostic performances of SS and NGS were systematically evaluated in a retrospective observational study including all index cases with a clinical diagnosis of EB in whom genome diagnostics was performed between 01 January 1994 and 01 January 2022 (n = 308), registered at the Dutch EB Expertise Centre. RESULTS: Over time, a genetic diagnosis was made in 289/308 (94%) EB cases. The diagnostic yield increased from 89% (SS) to 95% (NGS). Most importantly, NGS significantly reduced diagnostic turnaround time (39 days vs. 211 days, p < 0.001). The likelihood of detecting variants of uncertain significance and additional findings increased from 5% and 1% (SS) to 22% and 13% (NGS) respectively. CONCLUSIONS: Our study quantifies the benefit of NGS-based methods and demonstrate they have had a major impact on EB diagnostics through an increased diagnostic yield and a dramatically decreased turnaround time (39 days). Although our diagnostic yield is high (95%), further improvement of genome diagnostics is urgently needed to provide a genetic diagnosis in all EB patients.

The glutathione transferase Mu null genotype leads to lower 6-MMPR levels in patients treated with azathioprine but not with mercaptopurine.

The conversion of azathioprine (AZA) to mercaptopurine (MP) is mediated by glutathione transferase Mu1 (GSTM1), alpha1 (GSTA1) and alpha2 (GSTA2). We designed a case-control study with data from the TOPIC trial to explore the effects of genetic variation on steady state 6-methylmercaptopurine ribonucleotide (6-MMPR) and 6-thioguanine nucleotide (6-TGN) metabolite levels. We included 199 patients with inflammatory bowel disease (126 on AZA and 73 on MP). GSTM1-null genotype carriers on AZA had two-fold lower 6-MMPR levels than AZA users carrying one or two copies of GSTM1 (2239 (1006-4587) versus 4371 (1897-7369) pmol/8 × 108 RBCs; P<0.01). In patients on MP (control group) 6-MMPR levels were comparable (6195 (1551-10712) versus 6544 (1717-11600) pmol/8 × 108 RBCs; P=0.84). The 6-TGN levels were not affected by the GSTM1 genotype. The presence of genetic variants in GSTA1 and GSTA2 was not related to the 6-MMPR and 6-TGN levels.

Irreversible Electroporation in Hepatopancreaticobiliary Tumours.

Hepatopancreaticobiliary tumours are often diagnosed at an advanced disease stage, in which encasement or invasion of local biliary or vascular structures has already occurred. Irreversible electroporation (IRE) is an image-guided tumour ablation technique that induces cell death by exposing the tumour to high-voltage electrical pulses. The cellular membrane is disrupted, while sparing the extracellular matrix of critical tubular structures. The preservation of tissue integrity makes IRE an attractive treatment option for tumours in the vicinity of vital structures such as splanchnic blood vessels and major bile ducts. This article reviews current data and discusses future trends of IRE for hepatopancreaticobiliary tumours.

Mutations in C8orf37, encoding a ciliary protein, are associated with autosomal-recessive retinal dystrophies with early macular involvement.

Cone-rod dystrophy (CRD) and retinitis pigmentosa (RP) are clinically and genetically overlapping heterogeneous retinal dystrophies. By using homozygosity mapping in an individual with autosomal-recessive (ar) RP from a consanguineous family, we identified three sizeable homozygous regions, together encompassing 46 Mb. Next-generation sequencing of all exons, flanking intron sequences, microRNAs, and other highly conserved genomic elements in these three regions revealed a homozygous nonsense mutation (c.497T>A [p.Leu166(∗)]) in C8orf37, located on chromosome 8q22.1. This mutation was not present in 150 ethnically matched control individuals, single-nucleotide polymorphism databases, or the 1000 Genomes database. Immunohistochemical studies revealed C8orf37 localization at the base of the primary cilium of human retinal pigment epithelium cells and at the base of connecting cilia of mouse photoreceptors. C8orf37 sequence analysis of individuals who had retinal dystrophy and carried conspicuously large homozygous regions encompassing C8orf37 revealed a homozygous splice-site mutation (c.156-2A>G) in two siblings of a consanguineous family and homozygous missense mutations (c.529C>T [p.Arg177Trp]; c.545A>G [p.Gln182Arg]) in siblings of two other consanguineous families. The missense mutations affect highly conserved amino acids, and in silico analyses predicted that both variants are probably pathogenic. Clinical assessment revealed CRD in four individuals and RP with early macular involvement in two individuals. The two CRD siblings with the c.156-2A>G mutation also showed unilateral postaxial polydactyly. These results underline the importance of disrupted ciliary processes in the pathogenesis of retinal dystrophies.

Somatic mosaicism for the COL7A1 mutation p.Gly2034Arg in the unaffected mother of a patient with dystrophic epidermolysis bullosa pruriginosa.

Dystrophic epidermolysis bullosa (DEB) is a heritable blistering disorder caused by mutations in the type VII collagen gene, COL7A1. Although revertant mosaicism is well known in DEB, 'forward' somatic mosaicism, in which a pathogenic mutation arises on a wild-type (WT) background, extending beyond the germ cells, has not been reported. It is therefore unknown what proportion of sporadic dominant DEB (DDEB) cases result from de novo mutations or somatic mosaic parents. In the clinically unaffected mother of a patient with DDEB pruriginosa due to the p.Gly2034Arg mutation, we identified the p.Gly2034Arg mutation in a proportion of lymphocytes and skin cells (mutational load 10-25%). Our data emphasize that forward mosaicism occurs in DDEB and highlight that mutation analysis should always be performed in the parents of sporadic DDEB patients to confirm the de novo status of the mutation. Ultimately, this will reveal the frequency of true de novo mutations and somatic mosaicism in parents, which has important implications for genetic counselling. Our data indicate that the threshold of mutant type VII procollagen to develop DDEB must be higher than 10-25%, which provides a rationale for therapeutic approaches aimed at increasing the WT : mutant type VII collagen ratio.

RYR1-related myopathies: a wide spectrum of phenotypes throughout life.

BACKGROUND AND PURPOSE: Although several recent studies have implicated RYR1 mutations as a common cause of various myopathies and the malignant hyperthermia susceptibility (MHS) trait, many of these studies have been limited to certain age groups, confined geographical regions or specific conditions. The aim of the present study was to investigate the full spectrum of RYR1-related disorders throughout life and to use this knowledge to increase vigilance concerning malignant hyperthermia. METHODS: A retrospective cohort study was performed on the clinical, genetic and histopathological features of all paediatric and adult patients in whom an RYR1 mutation was detected in a national referral centre for both malignant hyperthermia and inherited myopathies (2008-2012). RESULTS: The cohort of 77 non-related patients (detection rate 28%) included both congenital myopathies with permanent weakness and 'induced' myopathies such as MHS and non-anaesthesia-related episodes of rhabdomyolysis or hyperCKemia, manifested throughout life and triggered by various stimuli. Sixty-one different mutations were detected, of which 24 were novel. Some mutations are present in both dominant (MHS) and recessive modes (congenital myopathy) of inheritance, even within families. Histopathological features included an equally wide spectrum, ranging from only subtle abnormalities to prominent cores. CONCLUSIONS: This broad range of RYR1-related disorders often presents to the general paediatric and adult neurologist. Its recognition is essential for genetic counselling and improving patients' safety during anaesthesia. Future research should focus on in vitro testing by the in vitro contracture test and functional characterization of the large number of RYR1 variants whose precise effects currently remain uncertain.

[Economic burden of Clostridium difficile enterocolitis in German hospitals based on routine DRG data]. / Ökonomische Auswirkungen einer Clostridium-difficile-Enterokolitis in deutschen Krankenhäusern auf der Basis von DRG-Kostendaten.

BACKGROUND: Clostridium difficile associated diarrhea (CDAD) is not only a increasing medical but also economical problem. METHODS: Data from the DRG project group of the German society for digestive and metabolic diseases (DGVS) were analyzed for CDAD. Out of 430,875 cases from 37 German hospitals 2,767 cases were grouped by having CDAD either as primary (PD) or secondary diagnosis (SD; likely to be from a hospital source) in an initial or recurring hospital stay (RD). For comparison non-CDAD cases from the same hospitals from that year where matched using propensity score matching. As endpoints we defined LOS (length of stay), difference of LOS to national average LOS, total costs per case and difference between costs and revenue for all three groups. RESULTS: Patients from the PD group (n = 817) showed a mean LOS of 11.2 days compared to 8.5 days for the control group, 4,132 € mean cost per case (536 € more than control) and a mean loss of -1,064 € per case compared to -636 €. In the SD group (n = 1,840) patients stayed in the hospital for 28.8 days (control: 18.1 days), had costs of 19,381 € (control: 13,082 €) and a loss of -3,442 € compared to -849 € in the control group. Recurring cases (RD; n = 110) showed a LOS of 37.3 days (control: 21.3 days), had even higher costs (20.755 € vs. 13,101 €) and higher losses (-4,196 € vs. -1,109 €). CONCLUSION: By extrapolating these findings CDAD not only harms patients but generates a yearly cost burden of 464 million € for the German healthcare system including a loss of 197 million € for German hospitals. To the authors' opinion sufficient measures against CDAD should include pre hospital risk reduction programs, introduction of effective therapeutic and hygienic strategies in hospitals as well as improvements in documentation for these cases to support further developments of the German DRG system.

[Improvement of cost allocation in gastroenterology by introduction of a novel service catalogue covering the complete spectrum of endoscopic procedures]. / Verbesserung der Kostenkalkulation in der Gastroenterologie durch Einführung eines neuen Leistungskatalogs für alle endoskopischen Prozeduren.

BACKGROUND: The German hospital reimbursement system (G-DRG) is incomplete for endoscopic interventions and fails to differentiate between complex and simple procedures. This is caused by outdated methods of personnel-cost allocation. METHODS: To establish an up-to-date service catalogue 50 hospitals made their anonymized expense-budget data available to the German-Society-of-Gastroenterology (DGVS). 2.499.900 patient-datasets (2011-2013) were used to classify operation-and-procedure codes (OPS) into procedure-tiers (e.g. colonoscopy with biopsy/colonoscopy with stent-insertion). An expert panel ranked these tiers according to complexity and assigned estimates of physician time. From June to November 2014 exact time tracking data for a total 38.288 individual procedures were collected in 119 hospitals to validate this service catalogue. RESULTS: In this three-step process a catalogue of 97 procedure-tiers was established that covers 99% of endoscopic interventions performed in German hospitals and assigned validated mean personnel-costs using gastroscopy as standard. Previously, diagnostic colonoscopy had a relative personnel-cost value of 1.13 (compared to gastroscopy 1.0) and rose to 2.16, whereas diagnostic ERCP increased from 1.7 to 3.62, more appropriately reflecting complexity. Complex procedures previously not catalogued were now included (e.g. gastric endoscopic submucosal dissection: 16.74). DISCUSSION: This novel service catalogue for GI-endoscopy almost completely covers all endoscopic procedures performed in German hospitals and assigns relative personnel-cost values based on actual physician time logs. It is to be included in the national coding recommendation and should replace all prior inventories for cost distribution. The catalogue will contribute to a more objective cost allocation and hospital reimbursement - at least until time tracking for endoscopy becomes mandatory.

Ablation of colorectal liver metastases by irreversible electroporation: results of the COLDFIRE-I ablate-and-resect study.

OBJECTIVES: Irreversible electroporation (IRE) is a new ablation technique that relies on high-voltage electrical pulses. This clinical study evaluates the pathological response of colorectal liver metastases (CRLM) treated with IRE and the clinical safety and feasibility. METHODS: Ten patients with resectable CRLM were included. During laparotomy, the metastases were treated with IRE and resected 60 min later. Safety and feasibility were assessed based on adverse events, laboratory values, technical success and intra-operative ultrasound findings. Tissue response was assessed using triphenyl tetrazolium chloride (TTC) vitality staining and (immuno)histochemical stainings (HE, complement-3d and caspase-3). RESULTS: Ten lesions with a mean diameter of 2.4 cm were successfully electroporated and resected, on average, 84 min later (range 51-153 min). One minor transient cardiac arrhythmia occurred during IRE. Ultrasound showed a sharply demarcated hypoechoic ablation zone around the tumour. TTC showed avitality of all lesions, covering the complete tumour in 8/10 lesions. Although immunohistochemistry proved heterogeneous and difficult to interpret within the tumours, it confirmed irreversible cell damage in the tumour-free margin of all specimens. CONCLUSIONS: This ablate-and-resect study demonstrated avitality caused by IRE of CRLM in humans. Further characterisation of tissue- and tumour-specific electrical properties is warranted to improve ablation protocols for maximised tissue ablation. KEY POINTS: • Irreversible electroporation induces cell death in colorectal liver metastases within 1 h. • The ablation zone shows a sharp demarcation between avital and vital tissue. • Apoptosis is involved in cell death of colorectal liver metastases after IRE. • Effects of IRE can be monitored real-time using intraoperative ultrasound. • Local electrical heterogeneities of tumour tissue may require tumour-specific ablation protocols.

Anaesthetic management during open and percutaneous irreversible electroporation.

BACKGROUND: Irreversible electroporation (IRE) is a novel tumour ablation technique involving repetitive application of electrical energy around a tumour. The use of pulsed electrical gradients carries a risk of cardiac arrhythmias, severe muscle contractions, and seizures. We aimed to identify IRE-related risks and the appropriate precautions for anaesthetic management. METHODS: All patients who were treated with IRE were prospectively included. Exclusion criteria were arrhythmias, congestive heart failure, active coronary artery disease, and epilepsy. All procedures were performed under general anaesthesia with complete muscle relaxation during ECG-synchronized pulsing. Adverse events, cardiovascular effects, blood samples, cerebral activity, and post-procedural pain were analysed. RESULTS: Twenty-eight patients underwent 30 IRE sessions for tumours in the liver, pancreas, kidney, and lesser pelvis. No major adverse events occurred during IRE. Median systolic and diastolic blood pressure increased by 44 mm Hg (range -7 to 108 mm Hg) and 19 mm Hg (range 1-50 mm Hg), respectively. Two transient minor cardiac arrhythmias without haemodynamic consequences were observed. Muscle contractions were mild and IRE caused no reactive brain activity on a simplified EEG. Pain in the first 24 h after percutaneous IRE was generally mild, but higher pain scores were reported after pancreatic treatment (mean VAS score 3; range 0-9). CONCLUSIONS: Side-effects during IRE on tumours in the liver, pancreas, kidney, and lesser pelvis seem mild and manageable when current recommendations for anaesthesia management, including deep muscle relaxation and ECG synchronized pulsing, are followed. Electrical pulses do not seem to cause reactive cerebral activity and evidence for pre-existing atrial fibrillation as an absolute contra-indication for IRE is questionable.

Bipolar radiofrequency ablation for symptomatic giant (>10 cm) hepatic cavernous haemangiomas: initial clinical experience.

AIM: To describe initial clinical experience with bipolar radiofrequency ablation (RFA) for symptomatic giant hepatic haemangiomas. MATERIALS AND METHODS: Four consecutive patients with a large-volume, symptomatic hepatic cavernous haemangioma of >10 cm were treated with bipolar RFA during laparotomy with ultrasound guidance. Complications were carefully noted. Clinical and radiological effectiveness were evaluated comparing baseline with 3 and 6 months follow-up of symptom assessments and upper abdominal magnetic resonance imaging (MRI) or computed tomography (CT). RESULTS: RFA was successfully performed for all four giant haemangiomas. No major complications were observed. Peri-procedural shrinking was remarkable and intermediate-term volume reduction ranged from 58-92% after 6 months. Symptom relief after 6 months was complete in two patients and considerable in the other two. CONCLUSION: Preliminary results suggest intra-operative bipolar RFA to be a safe, feasible, and effective technique for treatment of giant symptomatic hepatic cavernous haemangiomas.

Autosomal recessive cerebellar ataxias: the current state of affairs.

Among the hereditary ataxias, autosomal recessive cerebellar ataxias (ARCAs) encompass a diverse group of rare neurodegenerative disorders in which a cerebellar syndrome is the key clinical feature. The clinical overlap between the different cerebellar ataxias, the occasional atypical phenotypes, and the genetic heterogeneity often complicate the clinical management of such patients. Despite the steady increase in newly discovered ARCA genes, many patients with a putative ARCA cannot be genotyped yet, proving that more genes must be involved. This review presents an updated overview of the various ARCAs. The clinical and genetic characteristics of those forms with a known molecular genetic defect are discussed, along with the emerging insights in the underlying pathophysiological mechanisms.

A homozygous FKRP start codon mutation is associated with Walker-Warburg syndrome, the severe end of the clinical spectrum.

Dystroglycanopathies are a heterogeneous group of disorders caused by defects in the glycosylation pathway of alpha-dystroglycan. The clinical spectrum ranges from severe congenital muscular dystrophy with structural brain and eye involvement to a relatively mild adult onset limb-girdle muscular dystrophy without brain abnormalities and normal intelligence. Mutations have been identified in one of six putative or demonstrated glycosyltransferases. Many different FKRP mutations have been identified, which cover the complete clinical spectrum of dystroglycanopathies. In contrast to the other known genes involved in these disorders, genotype-phenotype correlations are not obvious for FKRP mutations. To date, no homozygous or compound heterozygous null mutations have been identified in FKRP, suggesting that null mutations in FKRP could result in embryonic lethality. We report a family with two siblings carrying a homozygous mutation in the start codon of FKRP that is likely to result in a loss of functional FKRP protein. The clinical phenotype of the patients was consistent with Walker-Warburg syndrome, the most severe disorder in the disease spectrum of dystroglycanopathies.

Hereditary spastic paraplegia due to SPAST mutations in 151 Dutch patients: new clinical aspects and 27 novel mutations.

BACKGROUND: In the clinically and genetically heterogeneous group of the hereditary spastic paraplegias (HSPs), mutations in the SPAST gene are most frequently found and cause a pure autosomal dominant form. OBJECTIVE: To provide the clinical and genetic characteristics of Dutch patients with HSP due to a SPAST mutation (SPG4). METHODS: SPAST mutation carriers were identified through a comprehensive national database search. Available medical records were reviewed. RESULTS: 151 mutation carriers carried 60 different changes in the SPAST gene, of which one was a known polymorphism, and 27 were novel. Missense mutations were most frequently found (39%). Clinical information was available from 72 mutation carriers. Age at onset ranged from 1 to 63 years with a bimodal peak distribution in the first decade and above age 30. The predominantly pure spastic paraplegia was accompanied by deep sensory disturbances and sphincter problems in almost 50%. An additional hand tremor was found in 10%. Patients with missense mutations and exon deletions did not reveal a distinctive phenotype. CONCLUSIONS: Dutch SPAST mutation carriers show a broad mutation spectrum, with 27 novel mutations in the present series. A bimodal peak distribution in age at onset was found and an accompanying tremor as peculiar feature of SPG4. The pathogenicity of S44L, the first exon 4 mutation, and a possible autosomal recessive mode of inheritance are discussed.

Autosomal recessive inheritance of GLUT1 deficiency syndrome.

GLUT1 deficiency syndrome (GLUT1DS) is understood as a monogenetic disease caused by heterozygous SLC2A1 gene mutations with autosomaldominant and sporadic transmission. We report on a six-year-old girl from an inbred Arab family with moderate global developmental delay, epilepsy, ataxia, hypotonia, and hypoglycorrhachia (CSF glucose 36 mg/dL; CSF lactate 1.09 mmol/L; CSF/blood glucose ratio 0.44). Molecular analysis of the SLC2A1 gene identified a novel homozygous c1402C>T (p. Arg468Trp) mutation in exon 10 in the index patient and her asymptomatic younger sister. The mutation was absent in 120 control alleles of healthy individuals as well as in 400 alleles of other GLUT1DS patients. Arg468 represents a highly conserved, functionally important amino acid residue in the GLUT1 carboxy-terminus essential for substrate recognition and transport. Both unaffected parents were heterozygous for the mutation. A younger brother and two family members were healthy and carried the GLUT1 wild type. A ketogenic diet effectively controlled seizures in the index patient. We conclude that GLUT1DS can be transmitted as an autosomal recessive disease and provide new insights into genetic counselling for this treatable disorder.

Exocrine pancreatic and enterocyte function in patients with advanced pancreatic cancer.

BACKGROUND & AIMS: Exocrine pancreatic function is affected in patients with locally advanced pancreatic cancer (LAPC), clinically leading to steatorrhea. It is unknown whether maldigestion and malabsorption can also be attributed to impaired intestinal enterocyte function. In this exploratory study enterocyte function was assessed in patients with locally advanced pancreatic cancer, treated with Irreversible Electroporation (IRE). METHODS: Enterocyte function was studied by Citrulline Generation Test (CGT). Intestinal absorption capacity of energy and fat was calculated from the differences between nutritional intake (four-days diary) and quantified fecal losses energy and fat in three-days feces collection. RESULTS: Twelve patients were included before IRE, and 5 patients had follow-up measurements. Fasted citrulline [CIT] and glutamine [GLU] levels were below reference levels of healthy subjects ([CIT] 38 ± 8 µmol/L; [GLU] 561 ± 77 µmol/L) both before ([CIT] 25 ± 9 µmol/L; [GLU] 65 ± 35 µmol/L) and after IRE ([CIT] 19 ± 9 µmol/L; [GLU] 53 ± 26 µmol/L) whereas CGT curves were normal, indicating normal enterocyte function (slope 0.21 ± 0.12 and 0.17 ± 0.07 µmol/L/min; [CIT] increment 63 ± 39 and 80 ± 44% respectively). Severe energy/fat malabsorption was present in 6 out of 12 patients with LAPC (mean loss 349 kcal/d, 13 g fat/d) before and in 4 out of 5 patients (mean loss 509 kcal/d, 32 g fat/d) after IRE respectively. CONCLUSIONS: Enterocyte function was generally within reference limits in patients with advanced pancreatic cancer. Severe malabsorption may be explained by exocrine pancreatic insufficiency.

Gene expression profiling in rheumatoid arthritis: current concepts and future directions.

Over the last years microarray technologies have generated new perspectives for the high-throughput analysis of biological systems. Nowadays, it is possible to monitor thousands of genes in a single experiment. This molecular profiling technology combined with standardised and validated clinical measurements can allow a more precise characterisation of a patient's phenotype, and may lead to the design of therapeutic protocols and procedures better tailored to an individual patient's needs. In this report we provide an overview of expression profiling studies in rheumatoid arthritis (RA). RA is a chronic inflammatory disease in which both genetic and environmental factors are involved. The precise molecular mechanisms underlying RA are not fully understood. A systematic literature search revealed nine array-based expression profiling studies in patients with RA. Findings from these studies were compared with those of linkage and genome-wide association (GWA) studies. Although we observed many differences in study design, analysis and interpretation of results between the different studies, we extracted two sets of genes: (1) those differentially expressed in more than one study, and (2) genes differentially expressed in at least one of the reviewed studies and present in RA linkage or GWA loci. We suggest that both sets of genes include interesting candidate genes for further study in RA.

The tumour necrosis factor receptor superfamily member 1b 676T>G polymorphism in relation to response to infliximab and adalimumab treatment and disease severity in rheumatoid arthritis.

OBJECTIVE: To assess the effect of a functional polymorphism (676T>G, M196R) in the tumour necrosis factor receptor super family 1b (TNFSF1b) gene on disease activity, radiological joint damage and response to infliximab and adalimumab treatment in patients with rheumatoid arthritis (RA). METHODS: Two cohorts of patients with RA were genotyped for the 676T>G polymorphism (rs1061622) in exon 6 of the TNFSF1b gene by restriction fragment length polymorphism analysis. One cohort (n = 234) included patients from the Dutch Rheumatoid Arthritis Monitoring register with detailed information on their response to anti-TNF therapy (infliximab and adalimumab), the other cohort comprised patients from a long-term observational early inception cohort at our centre (n = 248). RESULTS: The 676T>G polymorphism was not associated with anti-TNF response after 3 or 6 months of treatment. Linear regression analysis showed no significant difference in the progression of radiological joint damage during the first 3 and 6 years of disease between the three genotype groups (TT, TG and GG). Additionally, no difference in mean disease activity between genotypes was seen after 3 and 6 years of disease. CONCLUSION: Despite its demonstrated functionality, the 676T>G polymorphism in the TNFSF1b gene does not have a major role in either the response to anti-TNF therapy or in the disease severity or radiological progression in RA.

A natural history study of late onset spinal muscular atrophy types 3b and 4.

BACKGROUND: Spinal muscular atrophy (SMA) is caused by a homozygous deletion of the survival motor neuron (SMN)1 gene. The nearly identical SMN2 gene plays a disease modifying role. SMA is classified into four different subtypes based on age of onset and clinical course (SMA types 1-4). The natural history of early onset SMA types 1-3a has been studied extensively. Late onset SMA is rare and disease course has not been studied in detail. OBJECTIVE: To perform a prospective study on the clinical course and the correlation with SMN2 copy numbers of late onset SMA. METHODS: Patients fulfilling the diagnostic criteria for late onset SMA (types 3b and 4) were included in the study. At inclusion and follow-up, muscle strength, respiratory function, functional status and quality of life were assessed. SMN2 copy number was determined in all patients. RESULTS: Twelve patients were identified and included. Six patients were siblings from one family, two patients were brothers from a second family and four patients were sporadic cases. All patients carried four copies of the SMN2 gene. Median age of disease onset was 22.2 years (10-37). Age of disease onset in patients from family one was lower as compared to the other patients. None of the outcome measures changed after a follow-up of 2.5 years. Five patients reported an increase in fatigue and muscle weakness. None of the patients showed symptoms of respiratory insufficiency. CONCLUSIONS: This study indicates that late onset SMA is not characterized by disease progression and that alternative or surrogate disease markers are required for the design of future trials. This study confirms the finding that SMN2 copy number is a SMA disease course modifier.