Acute porphyrias – A neurological perspective

Acute hepatic porphyrias (AHP) can cause severe neurological symptoms involving the central, autonomic, and peripheral nervous system. Due to their relative rarity and their chameleon-like presentation, delayed diagnosis and misdiagnosis are common. AHPs are genetically inherited disorders that result from heme biosynthesis enzyme deficiencies and comprise four forms: acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP), and ALA-dehydratase porphyria (ALADP). Depending on the clinical presentation, the main differential diagnoses are Guillain-Barré syndrome and autoimmune encephalitis. Red flags that could raise the suspicion of acute porphyria are neurological symptoms starting after severe (abdominal) pain, in association with reddish urine, hyponatremia or photodermatitis, and the presence of encephalopathy and/or axonal neuropathy. We highlight the diagnostic difficulties by presenting three cases from our neurological intensive care unit and give a comprehensive overview about the diagnostic findings in imaging, electrophysiology, and neuropathology

A distinctive gene expression fingerprint in mentally retarded male patients reflects disease-causing defects in the histone demethylase KDM5C

Background: Mental retardation is a genetically heterogeneous disorder, as more than 90 genes for this disorder has been found on the X chromosome alone. In addition the majority of patients are non-syndromic in that they do not present with clinically recognisable features. This makes it difficult to determine the molecular cause of this disorder on the basis of the phenotype alone. Mutations in KDM5C (previously named SMCX or JARID1C), a gene that encodes a transcriptional regulator with histone demethylase activity specific for dimethylated and trimethylated H3K4, are a comparatively frequent cause of non-syndromic X-linked mental retardation (NS-XLMR). Specific transcriptional targets of KDM5C, however, are still unknown and the effects of KDM5C deficiency on gene expression have not yet been investigated. Results: By whole-mount in situ hybridisation we showed that the mouse homologue of KDM5C is expressed in multiple tissues during mouse development. We present the results of gene expression profiling performed on lymphoblastoid cell lines as well as blood from patients with mutations in KDM5C. Using whole genome expression arrays and quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) experiments, we identified several genes, including CMKOR1, KDM5B and KIAA0469 that were consistently deregulated in both tissues. Conclusions: Our findings shed light on the pathological mechanisms underlying mental retardation and have implications for future diagnostics of this heterogeneous disorder

A non-enzymatic function of 17 beta-hydroxysteroid dehydrogenase type 10 is required for mitochondrial integrity and cell survival

Deficiency of the mitochondrial enzyme 2-methyl-3-hydroxybutyryl-CoA dehydrogenase involved in isoleucine metabolism causes an organic aciduria with atypical neurodegenerative course. The disease-causing gene is HSD17B10 and encodes 17beta-hydroxysteroid dehydrogenase type 10 (HSD10), a protein also implicated in the pathogenesis of Alzheimer's disease. Here we show that clinical symptoms in patients are not correlated with residual enzymatic activity of mutated HSD10. Loss-of-function and rescue experiments in Xenopus embryos and cells derived from conditional Hsd17b10(-/-) mice demonstrate that a property of HSD10 independent of its enzymatic activity is essential for structural and functional integrity of mitochondria. Impairment of this function in neural cells causes apoptotic cell death whilst the enzymatic activity of HSD10 is not required for cell survival. This finding indicates that the symptoms in patients with mutations in the HSD17B10 gene are unrelated to accumulation of toxic metabolites in the isoleucine pathway and, rather, related to defects in general mitochondrial function. Therefore alternative therapeutic approaches to an isoleucine-restricted diet are required

Chromosome 22q Tumor Suppressor Gene Identification in Astrocytoma

Titelblatt und Inhaltsverzeichnis Einleitung Material und Methoden Ergebnisse Diskussion LiteraturverzeichnisAstrozytome und Glioblastome gehören zu den häufigsten primären Gehirntumoren im Erwachsenenalter. Mutationen und eine veränderte Genexpression sind an der Genese von Gehirntumoren beteiligt. Einige Veränderungen sind bereits identifiziert worden, wie z.B. Mutationen im TP53 Tumorsuppressorgen. Eine Vielzahl von Genen, die zur Tumorgenese beitragen, ist noch nicht bekannt. Die hohe Anzahl von Allelverlusten auf verschiedenen Chromosomen weist auf noch unbekannte Tumorsuppressorgene hin. Ein Verlust der Heterozygotie ( loss of heterozygosity , LOH) auf dem langen Arm von Chromosom 22 ist in astrozytären Tumoren mit einer Häufigkeit von 30 % beschrieben worden. Damit ergeben sich indirekte Hinweise, dass sich auf Chromosom 22 ein oder mehrere für Astrozytome wichtige, bisher unbekannte Tumorsuppressorgene befinden. Zur Identifizierung dieser potentiellen Tumorsuppressorgene wurde diese Studie durchgeführt. In einem ersten Schritt wurden 153 astrozytäre Tumore mit 11 polymorphen Mikrosatellitenmarkern untersucht, die den gesamten chromosomalen Arm 22q abdeckten. Insgesamt zeigten 49 Gliome (32 %) einen Allelverlust auf 22q. Davon hatten 17 Gliome (35 %) den gesamten chromosomalen Arm verloren und 32 Gliome (65 %) zeigten interstitielle Deletionen. Die Deletionsmuster von Tumoren mit interstitiellen Deletionen wurden dazu verwendet, gemeinsame Verlustzonen einzugrenzen. Dabei gelang die Identifizierung von zwei verschiedenen Deletionszonen. Einer centromeren Region (22q11.23-22q12) mit einer Größe von 3 Mb und einer telomeren Region (22q13.31-32) mit einer Größe von 2.7 Mb. Die Gene in diesen minimalen Verlustzonen wurden in einem zweiten Schritt mittels Internet-Datenbanken annotiert. Fünf Kandidatengene (MYO18B, DJ1042K10.2, MKL1, EP300 und BIK) wurden mittels SSCP auf Mutationen untersucht. Dieser Mechanismus der Tumorsuppressorgen-Inaktivierung konnte in den untersuchten Exonen ausgeschlossen werden. Zusätzlich wurden die Gene in den identifizierten Zonen einer Expressionsanalyse mittels Mikroarray unterzogen. Dabei wurden 10 Tumoren mit einem Allelverlust 22q mit 10 Tumoren ohne einen Allelverlust in ihrem Expressionsverhalten miteinander verglichen. Es wurden keine differentiell exprimierten Gene gefunden werden.Astrocytomas and glioblastomas are the most frequent primary brain tumors in adults. Mutations and altered expressions of multiple genes have been found to contribute to the genesis of these tumors. However, many factors in the genesis of astrocytic gliomas are not resolved yet. The frequent losses on several chromosomes indicate the role of still unidentified tumor suppressor genes. Loss of Heterozygosity (LOH) on 22q has been described in up to 30% of astrocytic tumors and may be associated with progression to anaplasia. This study was undertaken to identify a potential tumor suppressor gene on chromosome 22q. In a first step, a series of 153 astrocytic gliomas was examined with 11 polymorphic markers spanning these regions. 49 (32%) astrocytic gliomas exhibited LOH on 22q, 17 (35%) of which lost heterozygosity for all markers and 32 (65%) of which carried interstitial deletions. Two regions were identified on the physical DNA sequence. The centromeric region spans 3 Mb and the telomeric region 2.7 Mb. The reduced size of these regions allowed direct analysis of all genes included. It was possible to exclude genetic alterations in five candidate genes from both regions: MYO18B, DJ1042K10.2, MKL1, EP300 and BIK. Additionally the genes within the identified regions were examined using microarray technique. Thus, 10 tumors with and without LOH 22q were compared based on their expression levels. A differential gene expression was not identified

GAD Antibody-Associated Late-Onset Cerebellar Ataxia in Two Female Siblings

Background: Anti-glutamic acid decarboxylase antibody (GAD-ab)-associated cerebellar ataxia is a rare neurological disorder characterized by cerebellar symptoms concomitant with high GAD-ab levels in serum and cerebrospinal fluid (CSF). Case Report: We report on 2 female siblings (aged 74 and 76 years) presenting with gradual progression of rotational vertigo, gait ataxia and vertical diplopia, continuously progressing for 6 months and 6 years, respectively. Autoimmune laboratory examinations showed remarkably increased serum and CSF GAD-ab levels. Their medical histories revealed late-onset type 1 diabetes mellitus (T1DM) and other concomitant autoimmune disorders (Grave's disease, Hashimoto's thyroiditis). Cerebral MRI and laboratory examinations were unremarkable. The diagnosis of GAD-ab-associated cerebellar ataxia with particular brainstem involvement was established in both women. After the exclusion of an underlying malignancy, immunosuppressive therapy has been initiated in both patients, which resulted in stabilization in one and in clinical improvement in the other patient. Discussion: The unique association of autoantibody-mediated cerebellar ataxia and late-onset T1DM in 2 siblings with similar clinical and paraclinical phenotypes strengthens the concept that hereditary factors might play a relevant role also in autoimmune diseases so far considered to be sporadic. Moreover, the occurrence of continuous vertical diplopia broadens the clinical spectrum of GAD-ab-associated neurological syndromes

Werner Protein Protects Nonproliferating Cells from Oxidative DNA Damage

Werner syndrome, caused by mutations of the WRN gene, mimics many changes of normal aging. Although roles for WRN protein in DNA replication, recombination, and telomere maintenance have been suggested, the pathology of rapidly dividing cells is not a feature of Werner syndrome. To identify cellular events that are specifically vulnerable to WRN deficiency, we used RNA interference (RNAi) to knockdown WRN or BLM (the RecQ helicase mutated in Bloom syndrome) expression in primary human fibroblasts. Withdrawal of WRN or BLM produced accelerated cellular senescence phenotype and DNA damage response in normal fibroblasts, as evidenced by induction of γH2AX and 53BP1 nuclear foci. After WRN depletion, the induction of these foci was seen most prominently in nondividing cells. Growth in physiological (3%) oxygen or in the presence of an antioxidant prevented the development of the DNA damage foci in WRN-depleted cells, whereas acute oxidative stress led to inefficient repair of the lesions. Furthermore, WRN RNAi-induced DNA damage was suppressed by overexpression of the telomere-binding protein TRF2. These conditions, however, did not prevent the DNA damage response in BLM-ablated cells, suggesting a distinct role for WRN in DNA homeostasis in vivo. Thus, manifestations of Werner syndrome may reflect an impaired ability of slowly dividing cells to limit oxidative DNA damage

Clonal Analysis in Recurrent Astrocytic, Oligoastrocytic and Oligodendroglial Tumors Implicates <em>IDH1</em>- Mutation as Common Tumor Initiating Event

<div><h3>Background</h3><p>To investigate the dynamics of inter- and intratumoral molecular alterations during tumor progression in recurrent gliomas.</p> <h3>Methodology/Principal Findings</h3><p>To address intertumoral heterogeneity we investigated non- microdissected tumor tissue of 106 gliomas representing 51 recurrent tumors. To address intratumoral heterogeneity a set of 16 gliomas representing 7 tumor pairs with at least one recurrence, and 4 single mixed gliomas were investigated by microdissection of distinct oligodendroglial and astrocytic tumor components. All tumors and tumor components were analyzed for allelic loss of 1p/19q (LOH 1p/19q), for <em>TP53-</em> mutations and for R132 mutations in the <em>IDH1</em> gene. The investigation of non- microdissected tumor tissue revealed clonality in 75% (38/51). Aberrant molecular alterations upon recurrence were detected in 25% (13/51). 64% (9/14) of these were novel and associated with tumor progression. Loss of previously detected alterations was observed in 36% (5/14). One tumor pair (1/14; 7%) was significant for both. Intratumoral clonality was detected in 57% (4/7) of the microdissected tumor pairs and in 75% (3/4) of single microdissected tumors. 43% (3/7) of tumor pairs and one single tumor (25%) revealed intratumoral heterogeneity. While intratumoral heterogeneity affected both the <em>TP53</em>- mutational status and the LOH1p/19q status, all tumors with intratumoral heterogeneity shared the R132 <em>IDH1-</em> mutation as a common feature in both their microdissected components.</p> <h3>Conclusions/Significance</h3><p>The majority of recurrent gliomas are of monoclonal origin. However, the detection of divertive tumor cell clones in morphological distinct tumor components sharing <em>IDH1</em>- mutations as early event may provide insight into the tumorigenesis of true mixed gliomas.</p> </div

Non- microdissected tumors with intertumoral heterogeneity indicated by gain and/or loss of molecular alterations during tumor progression.

<p>Surgery: designates the individual center of tumor operation:</p><p>NL: Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.</p><p>B: Charité Universitätsmedizin, Berlin, Germany.</p><p>HD: University Hospital, Heidelberg, Germany.</p><p>#: number of all tumors analyzed.</p><p>n (P): number of individual tumor pairs.</p><p>P/R: identifies primary (P) and recurrent (R) tumor of each tumor pair.</p><p>ID: internal tumor ID.</p><p>Tissue: abbreviation of diagnosis based on histology.</p><p>het.: retained heterozygosity.</p><p>LOH: loss of heterozygosity.</p><p>pLOH: partial loss of heterozygosity.</p><p>mut: mutated <i>TP53/IDH1.</i></p><p>wt: wild type <i>TP53/IDH1.</i></p><p>n.d.: not determined.</p><p> <b>Bold characters in column:</b></p><p>n (P): highlight every second tumor pair of individual patients.</p><p>P/R: highlight every primary tumor of individual patients.</p><p><i>TP53</i> in detail: highlight the position of individual base exchanges in the affected codon of the <i>TP53</i>- gene.</p><p>In all remaining columns bold characters highlight tumor pairs with novel molecular alterations during tumor progression.</p><p> <b><i>Bold italic characters:</i></b></p><p>Highlight tumor pairs in which molecular alterations of the primary tumor are lost during tumor progression.</p

Non- microdissected cases/data analysis.

<p>tissue: abbreviation of diagnosis based on histology.</p><p>n: number of individual tumors analyzed.</p><p><b>Σ</b> (n): sum of cases with respective molecular finding in tumors of similar provenience but different tumor grading (<i>i.e.</i> OII/OIII (*), OAII/OAIII (∫), AII/AIII (§)).</p><p><b>Σ</b>%: percentage of a molecular finding in summed up tumors of similar provenience but different tumor grading.</p