Ton Feuth

Diagnostic Genome Profiling in Mental Retardation

Mental retardation (MR) occurs in 2%-3% of the general population. Conventional karyotyping has a resolution of 5-10 million bases and detects chromosomal alterations in approximately 5% of individuals with unexplained MR. The frequency of smaller submicroscopic chromosomal alterations in these patients is unknown. Novel molecular karyotyping methods, such as array-based comparative genomic hybridization (array CGH), can detect submicroscopic chromosome alterations at a resolution of 100 kb. In this study, 100 patients with unexplained MR were analyzed using array CGH for DNA copy-number changes by use of a novel tiling-resolution genomewide microarray containing 32,447 bacterial artificial clones. Alterations were validated by fluorescence in situ hybridization and/or multiplex ligation-dependent probe amplification, and parents were tested to determine de novo occurrence. Reproducible DNA copy-number changes were present in 97% of patients. The majority of these alterations were inherited from phenotypically normal parents, which reflects normal large-scale copy-number variation. In 10% of the patients, de novo alterations considered to be clinically relevant were found: seven deletions and three duplications. These alterations varied in size from 540 kb to 12 Mb and were scattered throughout the genome. Our results indicate that the diagnostic yield of this approach in the general population of patients with MR is at least twice as high as that of standard GTG-banded karyotyping.

Array-Based Comparative Genomic Hybridization for the Genomewide Detection of Submicroscopic Chromosomal Abnormalities

Microdeletions and microduplications, not visible by routine chromosome analysis, are a major cause of human malformation and mental retardation. Novel high-resolution, whole-genome technologies can improve the diagnostic detection rate of these small chromosomal abnormalities. Array-based comparative genomic hybridization allows such a high-resolution screening by hybridizing differentially labeled test and reference DNAs to arrays consisting of thousands of genomic clones. In this study, we tested the diagnostic capacity of this technology using approximately 3,500 flourescent in situ hybridization-verified clones selected to cover the genome with an average of 1 clone per megabase (Mb). The sensitivity and specificity of the technology were tested in normal-versus-normal control experiments and through the screening of patients with known microdeletion syndromes. Subsequently, a series of 20 cytogenetically normal patients with mental retardation and dysmorphisms suggestive of a chromosomal abnormality were analyzed. In this series, three microdeletions and two microduplications were identified and validated. Two of these genomic changes were identified also in one of the parents, indicating that these are large-scale genomic polymorphisms. Deletions and duplications as small as 1 Mb could be reliably detected by our approach. The percentage of false-positive results was reduced to a minimum by use of a dye-swap-replicate analysis, all but eliminating the need for laborious validation experiments and facilitating implementation in a routine diagnostic setting. This high-resolution assay will facilitate the identification of novel genes involved in human mental retardation and/or malformation syndromes and will provide insight into the flexibility and plasticity of the human genome.

Early stop polymorphism in human DECTIN-1 is associated with increased candida colonization in hematopoietic stem cell transplant recipients.

Background. Intensive treatment of hematological malignancies with hematopoietic stem cell transplantation (HSCT) is accompanied by a high incidence of opportunistic invasive fungal infection, but individual risk varies significantly. Dectin-1, a C-type lectin that recognizes 1,3-beta-glucans from fungal pathogens, including Candida species, is involved in the initiation of the immune response against fungi. Methods. Screening for the DECTIN-1 Y238X polymorphism within a group of 142 patients undergoing HSCT was correlated with Candida colonization and candidemia. Furthermore, functional studies were performed on the consequences of the polymorphism. Results. Patients bearing the Y238X polymorphism in the DECTIN-1 gene were more likely to be colonized with Candida species, compared with patients bearing wild-type DECTIN-1, necessitating more frequent use of fluconazole in the prevention of systemic Candida infection. Functional assays demonstrated a loss-of-function phenotype of the polymorphism, as shown by the decreased cytokine production by immune cells bearing this polymorphism. Conclusions. The Y238X polymorphism is associated with increased oral and gastrointestinal colonization with Candida species. This suggests a crucial role played by dectin-1 in the mucosal antifungal mechanisms in immunocompromised hosts. The finding that DECTIN-1 polymorphisms rendered HSCT recipients at increased risk for fungal complications may contribute to the selection of high-risk patients who should be considered for antifungal prophylaxis to prevent systemic candidiasis.

Mutations in the chromatin modifier gene KANSL1 cause the 17q21.31 microdeletion syndrome

We show that haploinsufficiency of KANSL1 is sufficient to cause the 17q21.31 microdeletion syndrome, a multisystem disorder characterized by intellectual disability, hypotonia and distinctive facial features. The KANSL1 protein is an evolutionarily conserved regulator of the chromatin modifier KAT8, which influences gene expression through histone H4 lysine 16 (H4K16) acetylation. RNA sequencing studies in cell lines derived from affected individuals and the presence of learning deficits in Drosophila melanogaster mutants suggest a role for KANSL1 in neuronal processes.

Subsidence of stand-alone cervical carbon fiber cages.

OBJECTIVE: To investigate the number of subsidences of inserted cervical carbon fiber cages and to define predictive factors for subsidence. METHODS: All patients treated for a cervical herniated disc and fusion with a cervical carbon fiber cage between January 2002 and December 2003 were retrospectively identified. The radiological examinations were reviewed, and, especially, the presence of subsidence was noted. Possible predictive factors for subsidence were determined before the investigation. RESULTS: In 69 patients, there were 96 cages inserted, of which 29.2% subsided. Of all factors investigated, only smoking seemed to be predictive for subsidence, whereas insertion at C6 to C7 clearly had a higher risk at subsidence. Subsidence was not related to outcome or fusion. CONCLUSION: Although the high number of subsidence of cages has never been described before, clinical outcome and fusion rate is comparable with the literature.

Guideline implementation results in a decrease of pressure ulcer incidence in critically ill patients.

Objective:To describe the short-term and long-term effects of a hospital-wide pressure ulcer prevention and treatment guideline on both the incidence and the time to the onset of pressure ulcers in critically ill patients. Design:Prospective cohort study. Setting:Adult intensive care department of a university medical center. Patients:Critically ill patients (n = 399). Interventions:A guideline for pressure ulcer care was implemented on all intensive care units. The attention of nurses for timely transfer to a specific pressure-reducing device was an important part of this guideline. Measurements and Main Results:Patient characteristics, demographics, pressure ulcer risk profile at admission, daily pressure ulcer grading, and type of mattress were determined to describe the short-term and long-term effects 3 and 12 months after the implementation. The incidence density of pressure ulcers grade II–IV decreased from 54 per 1000 patient days at baseline to 32 per 1000 days (p = .001) 12 months after the implementation. The median pressure ulcer-free time increased from 12 days to 19 days (hazard rate ratio, 0.58; p = .02). After adjustment for differences in risk factors in a Cox proportional hazard model, the number of preventive transfers to special mattresses was the strongest indicator for the decreased risk of pressure ulcers (hazard rate ratio, 0.22; p < .001). The number needed to treat to prevent one pressure ulcer during the first 9 days was six. Conclusions:The implementation of a guideline for pressure ulcer care resulted in a significant and sustained decrease in the development of grade II–IV pressure ulcers in critically ill patients. Timely transfer to a specific mattress (i.e., transfer before the occurrence of a pressure ulcer) was the main indicator for a decrease in pressure ulcer development.

Myocardial 2D strain echocardiography and cardiac biomarkers in children during and shortly after anthracycline therapy for acute lymphoblastic leukaemia (ALL): a prospective study

AIMS The aim of this study was to investigate myocardial 2D strain echocardiography and cardiac biomarkers in the assessment of cardiac function in children with acute lymphoblastic leukaemia (ALL) during and shortly after treatment with anthracyclines. METHODS AND RESULTS Cardiac function of 60 children with ALL was prospectively studied with measurements of cardiac troponin T (cTnT) and N-terminal-pro-brain natriuretic peptide (NT-pro-BNP) and conventional and myocardial 2D strain echocardiography before start (T = 0), after 3 months (T = 1), and after 1 year (T = 2), and were compared with 60 healthy age-matched controls. None of the patients showed clinical signs of cardiac failure or abnormal fractional shortening. Cardiac function decreased significantly during treatment and was significantly decreased compared with normal controls. Cardiac troponin T levels were abnormal in 11% of the patients at T = 1 and were significantly related to increased time to global peak systolic longitudinal strain at T = 2 (P = 0.003). N-terminal-pro-brain natriuretic peptide levels were abnormal in 13% of patients at T = 1 and in 20% at T = 2, absolute values increased throughout treatment in 59%. Predictors for abnormal NT-pro-BNP at T = 2 were abnormal NT-pro-BNP at T = 0 and T = 1, for abnormal myocardial 2D strain parameters at T = 2 cumulative anthracycline dose and z-score of the diastolic left ventricular internal diameter at baseline. CONCLUSION Children with newly diagnosed ALL showed decline of systolic and diastolic function during treatment with anthracyclines using cardiac biomarkers and myocardial 2D strain echocardiography. N-terminal-pro-brain natriuretic peptide levels were not related to echocardiographic strain parameters and cTnT was not a predictor for abnormal strain at T = 2.Therefore, the combination of cardiac biomarkers and myocardial 2D strain echocardiography is important in the assessment of cardiac function of children with ALL treated with anthracyclines.

Development of a model with which to predict the life expectancy of patients with spinal epidural metastasis

The surgical treatment of spinal epidural metastasis is evolving. To be a surgical candidate, a patient should have a life expectancy of at least 3 months. Estimation of survival by experienced specialists has proven to be unreliable.

Intestinal Damage Determines the Inflammatory Response and Early Complications in Patients Receiving Conditioning for a Stem Cell Transplantation

Background Stem cell transplantation (SCT) is still complicated by the occurrence of fever and inflammatory complications attributed to neutropenia and subsequent infectious complications. The role of mucosal barrier injury (MBI) of the intestinal tract therein has received little attention. Methods We performed a retrospective analysis in 163 SCT recipients of which data had been collected prospectively on intestinal damage (citrulline), inflammation (C-reactive protein), and neutrophil count. Six different conditioning regimens were studied; 5 myeloablative (MA) and 1 non-myeloablative (NMA). Linear mixed model multivariate and AUC analyses were used to define the role of intestinal damage in post-SCT inflammation. We also studied the relationship between the degree of intestinal damage and the occurrence of early post-SCT complications. Results In the 5 MA regimen there was a striking pattern of inflammatory response that coincided with the occurrence of severe intestinal damage. This contrasted with a modest inflammatory response seen in the NMA regimen in which intestinal damage was limited. With linear mixed model analysis the degree of intestinal damage was shown the most important determinant of the inflammatory response, and both neutropenia and bacteremia had only a minor impact. AUC analysis revealed a strong correlation between citrulline and CRP (Pearson correlation r = 0.96). Intestinal damage was associated with the occurrence of bacteremia and acute lung injury, and influenced the kinetics of acute graft-versus-host disease. Conclusion The degree of intestinal damage after myeloablative conditioning appeared to be the most important determined the inflammatory response following SCT, and was associated with inflammatory complications. Studies should explore ways to ameliorate cytotoxic therapy-induced intestinal damage in order to reduce complications associated with myeloablative conditioning therapy.

Abnormal NT-pro-BNP levels in asymptomatic long-term survivors of childhood cancer treated with anthracyclines.

Anthracycline‐induced cardiotoxicity can cause serious health problems for an increasing number of survivors of childhood malignancies. The aims of this study were to document plasma concentrations of cardiac troponin T (cTnT) and NT‐pro‐brain natriuretic peptide (NT‐pro‐BNP) in a large group of asymptomatic long‐term survivors of childhood cancer treated with anthracyclines, and to study the relation of the abnormal biomarker levels with different risk factors for anthracycline‐induced cardiotoxicity and conventional echocardiographic parameters.