Anders Paetau

A hexanucleotide repeat expansion in C9ORF72 is the cause of chromosome 9p21-linked ALS-FTD

The chromosome 9p21 amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) locus contains one of the last major unidentified autosomal-dominant genes underlying these common neurodegenerative diseases. We have previously shown that a founder haplotype, covering the MOBKL2b, IFNK, and C9ORF72 genes, is present in the majority of cases linked to this region. Here we show that there is a large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 on the affected haplotype. This repeat expansion segregates perfectly with disease in the Finnish population, underlying 46.0% of familial ALS and 21.1% of sporadic ALS in that population. Taken together with the D90A SOD1 mutation, 87% of familial ALS in Finland is now explained by a simple monogenic cause. The repeat expansion is also present in one-third of familial ALS cases of outbred European descent, making it the most common genetic cause of these fatal neurodegenerative diseases identified to date.

Germline mutations in FH predispose to dominantly inherited uterine fibroids, skin leiomyomata and papillary renal cell cancer.

Uterine leiomyomata (fibroids) are common and clinically important tumors, but little is known about their etiology and pathogenesis1,2,3. We previously mapped a gene that predisposes to multiple fibroids, cutaneous leiomyomata and renal cell carcinoma to chromosome 1q42.3–q43 (refs 4–6). Here we show, through a combination of mapping critical recombinants, identifying individuals with germline mutations and screening known and predicted transcripts, that this gene encodes fumarate hydratase, an enzyme of the tricarboxylic acid cycle. Leiomyomatosis-associated mutations are predicted to result in absent or truncated protein, or substitutions or deletions of highly conserved amino acids. Activity of fumarate hydratase is reduced in lymphoblastoid cells from individuals with leiomyomatosis. This enzyme acts as a tumor suppressor in familial leiomyomata, and its measured activity is very low or absent in tumors from individuals with leiomyomatosis. Mutations in FH also occur in the recessive condition fumarate hydratase deficiency7,8,9,10,11, and some parents of people with this condition are susceptible to leiomyomata. Thus, heterozygous and homozygous or compound heterozygous mutants have very different clinical phenotypes. Our results provide clues to the pathogenesis of fibroids and emphasize the importance of mutations of housekeeping and mitochondrial proteins in the pathogenesis of common types of tumor12,13,14.Uterine leiomyomata (fibroids) are common and clinically important tumors, but little is known about their etiology and pathogenesis. We previously mapped a gene that predisposes to multiple fibroids, cutaneous leiomyomata and renal cell carcinoma to chromosome 1q42.3–q43 (refs 4–6). Here we show, through a combination of mapping critical recombinants, identifying individuals with germline mutations and screening known and predicted transcripts, that this gene encodes fumarate hydratase, an enzyme of the tricarboxylic acid cycle. Leiomyomatosis-associated mutations are predicted to result in absent or truncated protein, or substitutions or deletions of highly conserved amino acids. Activity of fumarate hydratase is reduced in lymphoblastoid cells from individuals with leiomyomatosis. This enzyme acts as a tumor suppressor in familial leiomyomata, and its measured activity is very low or absent in tumors from individuals with leiomyomatosis. Mutations in FH also occur in the recessive condition fumarate hydratase deficiency, and some parents of people with this condition are susceptible to leiomyomata. Thus, heterozygous and homozygous or compound heterozygous mutants have very different clinical phenotypes. Our results provide clues to the pathogenesis of fibroids and emphasize the importance of mutations of housekeeping and mitochondrial proteins in the pathogenesis of common types of tumor.

Remodeling of Saccular Cerebral Artery Aneurysm Wall Is Associated With Rupture: Histological Analysis of 24 Unruptured and 42 Ruptured Cases

Background and Purpose— The cellular mechanisms of degeneration and repair preceding rupture of the saccular cerebral artery aneurysm wall need to be elucidated for rational design of growth factor or drug-releasing endovascular devices. Methods— Patient records, preoperative vascular imaging studies, and the snap-frozen fundi resected after microsurgical clipping from 66 aneurysms were studied. Immunostainings for markers of smooth muscle cell (SMC) phenotype, proliferation, and inflammatory cell subtypes and TUNEL reaction were performed. Results— Unruptured (24) and ruptured (42) aneurysms had similar dimensions (median diameter in unruptured 6 mm; median in ruptured 7 mm; P=0.308). We identified 4 basic types of aneurysm wall that associated with rupture: (1) endothelialized wall with linearly organized SMCs (17/66; 42% ruptured), (2) thickened wall with disorganized SMCs (20/66; 55% ruptured), (3) hypocellular wall with either myointimal hyperplasia or organizing luminal thrombosis (14/66; 64% ruptured), and (4) an extremely thin thrombosis-lined hypocellular wall (15/66; 100% ruptured). Apoptosis, de-endothelialization, luminal thrombosis, SMC proliferation, and T-cell and macrophage infiltration associated with rupture. Furthermore, macrophage infiltration associated with SMC proliferation, and both were increased in ruptured aneurysms resected <12 hours from rupture, suggesting that these were not just reactive changes. Conclusions— Before rupture, the wall of saccular cerebral artery aneurysm undergoes morphological changes associated with remodeling of the aneurysm wall. Some of these changes, like SMC proliferation and macrophage infiltration, likely reflect ongoing repair attempts that could be enhanced with pharmacological therapy.

Mitochondrial DNA Polymerase W748S Mutation: A Common Cause of Autosomal Recessive Ataxia with Ancient European Origin

Mutations in the catalytic subunit of the mitochondrial DNA polymerase gamma (POLG) have been found to be an important cause of neurological disease. Recently, we and collaborators reported a new neurodegenerative disorder with autosomal recessive ataxia in four patients homozygous for two amino acid changes in POLG: W748S in cis with E1143G. Here, we studied the frequency of this allele and found it to be among the most common genetic causes of inherited ataxia in Finland. We identified 27 patients with mitochondrial recessive ataxia syndrome (MIRAS) from 15 Finnish families, with a carrier frequency in the general population of 1 : 125. Since the mutation pair W748S+E1143G has also been described in European patients, we examined the haplotypes of 13 non-Finnish, European patients with the W748S mutation. Haplotype analysis revealed that all the chromosomes carrying these two changes, in patients from Finland, Norway, the United Kingdom, and Belgium, originate from a common ancient founder. In Finland and Norway, long, common, northern haplotypes, outside the core haplotype, could be identified. Despite having identical homozygous mutations, the Finnish patients with this adult- or juvenile-onset disease had surprisingly heterogeneous phenotypes, albeit with a characteristic set of features, including ataxia, peripheral neuropathy, dysarthria, mild cognitive impairment, involuntary movements, psychiatric symptoms, and epileptic seizures. The high carrier frequency in Finland, the high number of patients in Norway, and the ancient European founder chromosome indicate that this newly identified ataxia should be considered in the first-line differential diagnosis of progressive ataxia syndromes.

Endothelial ICAM-1 Expression Associated With Inflammatory Cell Response in Human Ischemic Stroke

BACKGROUND After focal brain ischemia, leukocytes adhere to the perturbed endothelium and are believed to aggravate reperfusion injury. Although ischemia-induced upregulation of endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and P-selectin, has been observed in experimental animals, the mechanism of cerebral leukocyte infiltration and thus therapeutic possibilities to reduce it in humans are uncertain. METHODS AND RESULTS We counted the granulocytes, mononuclear phagocytes, and the percentages of cerebral microvessels expressing ICAM-1 by applying immunohistochemistry on brain sections showing a variable degree of neuronal damage from 11 human subjects who died 15 hours to 18 days after ischemic stroke and from normal control brains. In infarcted regions, granulocytes were detected as early as at 15 hours after injury (11.3 versus 0.5 cells/mm2 in noninfarcted hemisphere); their amount exceeded 200 cells/mm2 by 2.2 days but was back to normal level at 6.3 and 8.5 days. Acute infarctions (0.6 to 8.5 days) harbored significantly more ICAM-1-stained microvessels (up to 97% of microvessels at 1.8 days) than the noninfarcted hemisphere (P < .001), although the noninfarcted hemisphere (1.8 to 6.3 days) also showed higher ICAM-1 expression than controls. In the absence of ICAM-1 upregulation, macrophages (> 200/mm2) were abundant in the core of neuronal damage at 17 and 18 days. CONCLUSIONS The striking upregulation of endothelial ICAM-1 expression, functioning in concert with chemotactic factors, may cause granulocyte infiltration during the first 3 days after stroke. This study may support the usage and timing of antibody infusions to block endothelial adhesion molecules in an attempt to reduce leukocyte-induced damage in stroke.

ERG Transcription Factor as an Immunohistochemical Marker for Vascular Endothelial Tumors and Prostatic Carcinoma

ERG, an ETS family transcription factor, is known to be expressed in endothelial cells, and oncogenic ERG gene fusions occur in subsets of prostatic carcinoma, acute myeloid leukemia, and Ewing sarcoma. In this study, we immunohistochemically investigated nuclear ERG expression using a new monoclonal antibody, CPDR ERG-MAb, that is highly specific for detecting ERG protein and ERG-expressing prostate carcinomas. A broad range of vascular endothelial (n=250), other mesenchymal (n=973), and epithelial tumors (n=657) was examined to determine the use of ERG immunohistochemistry in surgical pathology. Only immunostains with ERG-positive normal endothelia (internal control) were considered valid, and only nuclear staining was considered to be positive. In adult tissues, ERG was restricted to endothelial cells and to a subset of bone marrow precursors, but early fetal mesenchyme and subpopulations of fetal cartilage were also positive. In vascular tumors, ERG was expressed in endothelia of all hemangiomas and lymphangiomas, and typically extensively expressed in 96 of 100 angiosarcomas, 42 of 43 epithelioid hemangioendotheliomas, and all 26 Kaposi sarcomas. Among nonvascular mesenchymal tumors, only blastic extramedullary myeloid tumors (7 of 10) and rare Ewing sarcomas (2 of 29) were positive. Among epithelial tumors, 30 of 66 prostatic adenocarcinomas showed focal-to-extensive ERG positivity, with no immunoreactivity in the normal prostate. Other carcinomas and epithelial tumors (n=643) were ERG negative, with the exception of 1 of 42 large cell undifferentiated pulmonary carcinomas and 1 of 27 mesotheliomas, each of which showed focal nuclear ERG positivity. On the basis of the above observations, ERG is a highly specific new marker for benign and malignant vascular tumors. Among epithelial tumors, ERG shows a great promise as a marker to identify prostatic carcinoma in both primary and metastatic settings.

FGF-21 as a biomarker for muscle-manifesting mitochondrial respiratory chain deficiencies: a diagnostic study

BACKGROUND Muscle biopsy is the gold standard for diagnosis of mitochondrial disorders because of the lack of sensitive biomarkers in serum. Fibroblast growth factor 21 (FGF-21) is a growth factor with regulatory roles in lipid metabolism and the starvation response, and concentrations are raised in skeletal muscle and serum in mice with mitochondrial respiratory chain deficiencies. We investigated in a retrospective diagnostic study whether FGF-21 could be a biomarker for human mitochondrial disorders. METHODS We assessed samples from adults and children with mitochondrial disorders or non-mitochondrial neurological disorders (disease controls) from seven study centres in Europe and the USA, and recruited healthy volunteers (healthy controls), matched for age where possible, from the same centres. We used ELISA to measure FGF-21 concentrations in serum or plasma samples (abnormal values were defined as >200 pg/mL). We compared these concentrations with values for lactate, pyruvate, lactate-to-pyruvate ratio, and creatine kinase in serum or plasma and calculated sensitivity, specificity, and positive and negative predictive values for all biomarkers. FINDINGS We analysed serum or plasma from 67 patients (41 adults and 26 children) with mitochondrial disorders, 34 disease controls (22 adults and 12 children), and 74 healthy controls. Mean FGF-21 concentrations in serum were 820 (SD 1151) pg/mL in adult and 1983 (1550) pg/mL in child patients with respiratory chain deficiencies and 76 (58) pg/mL in healthy controls. FGF-21 concentrations were high in patients with mitochondrial disorders affecting skeletal muscle but not in disease controls, including those with dystrophies. In patients with abnormal FGF-21 concentrations in serum, the odds ratio of having a muscle-manifesting mitochondrial disease was 132·0 (95% CI 38·7-450·3). For the identification of muscle-manifesting mitochondrial disease, the sensitivity was 92·3% (95% CI 81·5-97·9%) and specificity was 91·7% (84·8-96·1%). The positive and negative predictive values for FGF-21 were 84·2% (95% CI 72·1-92·5%) and 96·1 (90·4-98·9%). The accuracy of FGF-21 to correctly identify muscle-manifesting respiratory chain disorders was better than that for all conventional biomarkers. The area under the receiver-operating-characteristic curve for FGF-21 was 0·95; by comparison, the values for other biomarkers were 0·83 lactate (p=0·037, 0·83 for pyruvate (p=0·015), 0·72 for the lactate-to-pyruvate ratio (p=0·0002), and 0·77 for creatine kinase (p=0·013). INTERPRETATION Measurement of FGF-21 concentrations in serum identified primary muscle-manifesting respiratory chain deficiencies in adults and children and might be feasible as a first-line diagnostic test for these disorders to reduce the need for muscle biopsy. FUNDING Sigrid Jusélius Foundation, Jane and Aatos Erkko Foundation, Molecular Medicine Institute of Finland, University of Helsinki, Helsinki University Central Hospital, Academy of Finland, Novo Nordisk, Arvo and Lea Ylppö Foundation.

The gene disrupted in Marinesco-Sjögren syndrome encodes SIL1, an HSPA5 cochaperone.

We identified the gene underlying Marinesco-Sjögren syndrome, which is characterized by cerebellar ataxia, progressive myopathy and cataracts. We identified four disease-associated, predicted loss-of-function mutations in SIL1, which encodes a nucleotide exchange factor for the heat-shock protein 70 (HSP70) chaperone HSPA5. These data, together with the similar spatial and temporal patterns of tissue expression of Sil1 and Hspa5, suggest that disturbed SIL1-HSPA5 interaction and protein folding is the primary pathology in Marinesco-Sjögren syndrome.

Evolution of Cerebral Tumor Necrosis Factor-α Production During Human Ischemic Stroke

Background and Purpose— Tumor necrosis factor-&agr; (TNF-&agr;) is detected in ischemic brain cells in experimental animal models and is believed to play an important role in apoptosis. However, the natural expression of TNF-&agr; during human stroke is not known. Methods— We examined TNF-&agr; immunohistochemistry and terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling (TUNEL) in brain samples of stroke victims (n=16) after variable survival (15 hours to 18 days). Systemic TNF-&agr; content from a separate cohort including severe or lethal stroke cases (n=26) was also assayed. Results— Neuronal TNF-&agr; was demonstrated from 0.6 to 5.4 days after the onset of stroke symptoms, peaking bilaterally during days 2 and 3. Bilateral glial TNF-&agr; immunoreactivity was detected during the acute phase, with the astrocytic TNF-&agr; expression dominating in later phases and persisting contralaterally to the infarct in more matured phases (17 to 18 days). Invading inflammatory cells were TNF-&agr; immunopositive beginning on the third day. Besides, vascular wall structures showed immunoreactivity sporadically. TNF-&agr; levels were mostly nondetectable in peripheral blood. TUNEL labeling and TNF-&agr; staining overlapped, although not completely, during the first days. Conclusions— The data support the hypothesis that TNF-&agr; may be involved both in the acute propagation of inflammatory processes and cell death and possibly in the more delayed reconstitutive processes of human ischemic stroke.

A novel α-synuclein mutation A53E associated with atypical multiple system atrophy and Parkinson's disease-type pathology

We describe the clinical, neuropathological, and genetic features of a Finnish patient with a novel α-synuclein (SNCA) mutation A53E. The patient was clinically diagnosed with atypical Parkinsons disease (PD) with age of onset at 36 years. In the neuropathological analysis performed at the age of 60 years, highly abundant SNCA pathology was observed throughout the brain and spinal cord showing features of multiple system atrophy and PD. Neuronal and glial (including oligodendroglial) SNCA inclusions and neurites were found to be particularly prominent in the putamen, caudatus, amygdala, temporal and insular cortices, gyrus cinguli, and hippocampus CA2-3 region. These areas as well as the substantia nigra and locus coeruleus showed neuronal loss and gliosis. We also found TDP-43 positive but mostly SNCA negative perinuclear inclusions in the dentate fascia of the hippocampus. The A53E mutation was found in 2 other relatives who had parkinsonism. Our results suggest that the novel SNCA A53E substitution is a causative mutation resulting clinically in parkinsonism and pathologically in severe multiple system atrophy- and PD-type phenotype.