[Multidrug Resistant Organisms (MDRO) in Rehabilitation: Prevalence and Risk Factors for MRGN and VRE]. / Multiresistente Erreger (MRE) in der Rehabilitation: Prävalenz und Risikofaktoren für MRGN und VRE.

BACKGROUND: After a first large-scale study on multi-drug resistant organisms (MDRO) in rehabilitation facilities in 2014, the Rhine-Main network on MDRO carried out another investigation in 2019. With regard to the recently published KRINKO recommendations on multidrug resistant enterococci, now vancomycin -resistant enterococci (VRE) and multi-drug resistant gram-negative pathogens (3MRGN and 4MRGN, i. e. gramnegative organisms resistant against 3 resp. 4 groups of antiinfectiva) were investigated. MATERIAL AND METHODS: A total of 16 hospitals took part, including one clinic for early neurological rehabilitation (ENR). Patient participation was voluntary. Rectal swabs were analyzed in a medical-microbiological laboratory (certified according to DIN ISO 15189) using standard methods (including MALDI-TOF-MS and VITEK 2 resistance testing according to EUCAST). By using the standardized questionnaire of the Europe-wide HALT examination (healthcare associated infections in long-term care facilities), patient characteristics (age, gender, hospital, surgical and MDRO medical history, Medical devices, current antibiotic therapy etc.) were collected. RESULTS: 928 patients took part in the study, 895 from general rehabilitation facilities (GR) and 33 from early neurological rehabilitation (ENR). 65% of GR patients (ENR 100%) had been hospitalized in the previous 6 months, 29% (ENR 100%) of the patients had been admitted directly from a hospital, 22% (ENR 64%) had received antibiotic therapy in the last 3 months. Medical devices were rarely used in GR patients with 1% overall, but often in the ENR with 61% urinary catheters and 36% vascular catheters. 2.2% (ENR 33.3%) of GR patients were colonized with VRE and 6.7% (ENR 18.2%) with 3MRGN; one patient exhibited a 4MRGN (ENR 0). DISCUSSION: Compared to our previous study, there were no significant changes in the patient characteristics. The VRE prevalence was low at 3.3%, the prevalence of 3MRGN was higher compared to 2014 (7.1% vs. 3.6%). Risk factors for VRE and 3MRGN colonization (significant increased odds ratio) were: history of hospital treatment and an increased need for care due to restricted mobility, incontinence and disorientation. In addition, previous antibiotic treatment and skin barrier injuries due to Medical devices or wounds were detected as further risk factors for VRE colonization.

Visual AIDS for multimodal treatment options to support decision making of patients with colorectal cancer.

BACKGROUND: A variety of multimodal treatment options are available for colorectal cancer and many patients want to be involved in decisions about their therapies. However, their desire for autonomy is limited by lack of disease-specific knowledge. Visual aids may be helpful tools to present complex data in an easy-to-understand, graphic form to lay persons. The aim of the present study was to evaluate the treatment preferences of healthy persons and patients using visual aids depicting multimodal treatment options for colorectal cancer. METHODS: We designed visual aids for treatment scenarios based on four key studies concerning multimodal treatment of colorectal cancer. The visual aids were composed of diagrams depicting outcome parameters and side effects of two treatment options. They were presented to healthy persons (n = 265) and to patients with colorectal cancer (n = 102). RESULTS: Most patients and healthy persons could make immediate decisions after seeing the diagrams (range: 88%-100%). Patients (79%) chose the intensive-treatment option in the scenario with a clear survival benefit. In scenarios without survival benefit, all groups clearly preferred the milder treatment option (range: 78% - 90%). No preference was seen in the scenario depicting equally intense treatment options with different timing (neoadjuvant vs. adjuvant) but without survival benefit. CONCLUSIONS: Healthy persons' and patients' decisions using visual aids seem to be influenced by quality-of-life aspects rather than recurrence rates especially in situations without survival benefit. In the future visual aids may help to improve the management of patients with colorectal cancer.

Management of patients with multidrug-resistant organisms in rehabilitation facilities. Results of a survey in the Rhine-Main region, Germany, 2019.

Introduction: Multidrug-resistant organisms (MDRO) are a problem in medical facilities, including rehabilitation facilities in Germany. The national recommendations of the Commission for Hospital Hygiene and Infection Prevention (KRINKO) for prevention of and dealing with patients affected by MDRO are obligatory in rehabilitation facilities. A survey on the management of patients with MDRO in rehabilitation facilities in the Rhine-Main area is presented below. Materials and methods: The questions from a recently published survey in 45 rehabilitation facilities in 26 European countries (Doherty et al., 2019) were largely adopted unchanged: the type, size, and organization of the facility, availability of guidelines on MDRO, screening and (estimated) prevalence of MDRO, as well as special hygiene measures or restrictions for patients with MDRO. Results: 22 of the 43 institutions contacted participated (58%). All facilities had specific recommendations on how to deal with MDRO and more than 95% had adequate hygiene staff. The facilities encompassed 4,369 beds, with 3,909 (89%) of them in single-bed rooms, and only a few offered 3-bed rooms. About 20% of patients in general rehabilitation and 100% in early neurological rehabilitation are screened on admission. Six (27%) facilities refused to accept patients with MDRO. 40% of the facilities treated these patients in their own room and/or in a separate area. 27% of the facilities prohibited eating in the dining room and participating in hydrotherapy. Only 6 (27%) of the rehabilitation centers indicated that patients with MDRO are allowed to participate in full rehabilitation programs. Discussion: In accordance with the results of Doherty et al. (2019), there were many restrictions for rehabilitation patients with MDRO, indicating considerable need for improvement. Necessary hygiene recommendations to avoid the transmission of MDRO must not lead to rejection of inpatient rehabilitation or to less intensive rehabilitation.

Leigh-like subacute necrotising encephalopathy in Yorkshire Terriers: neuropathological characterisation, respiratory chain activities and mitochondrial DNA.

Our knowledge of molecular mechanisms underlying mitochondrial disorders in humans has increased considerably during the past two decades. Mitochondrial encephalomyopathies have sporadically been reported in dogs. However, molecular and biochemical data that would lend credence to the suspected mitochondrial origin are largely missing. This study was aimed to characterise a Leigh-like subacute necrotising encephalopathy (SNE) in Yorkshire Terriers and to shed light on its enzymatic and genetic background. The possible resemblance to SNE in Alaskan Huskies and to human Leigh syndrome (LS) was another focus of interest. Eleven terriers with imaging and/or gross evidence of V-shaped, non-contiguous, cyst-like cavitations in the striatum, thalamus and brain stem were included. Neuropathological examinations focussed on muscle, brain pathology and mitochondrial ultrastructure. Further investigations encompassed respiratory-chain activities and the mitochondrial DNA. In contrast to mild non-specific muscle findings, brain pathology featured the stereotypic triad of necrotising grey matter lesions with relative preservation of neurons in the aforementioned regions, multiple cerebral infarcts, and severe patchy Purkinje-cell degeneration in the cerebellar vermis. Two dogs revealed a reduced activity of respiratory-chain-complexes I and IV. Genetic analyses obtained a neutral tRNA-Leu(UUR) A-G-transition only. Neuropathologically, SNE in Yorkshire Terriers is nearly identical to the Alaskan Husky form and very similar to human LS. This study, for the first time, demonstrated that canine SNE can be associated with a combined respiratory chain defect. Mitochondrial tRNA mutations and large genetic rearrangements were excluded as underlying aetiology. Further studies, amongst relevant candidates, should focus on nuclear encoded transcription and translation factors.

Wolfram syndrome-associated mutations lead to instability and proteasomal degradation of wolframin.

Wolfram syndrome is caused by mutations in WFS1 encoding wolframin, a polytopic membrane protein of the endoplasmic reticulum. Here, we investigated the molecular pathomechanisms of four missense and two truncating mutations in WFS1. Expression in COS-7 cells as well as direct analysis of patient cells revealed that WFS1 mutations lead to drastically reduced steady-state levels of wolframin. All mutations resulted in highly unstable proteins which were delivered to proteasomal degradation. No wolframin aggregates were found in patient cells suggesting that Wolfram syndrome is not a disease of protein aggregation. Rather, WFS1 mutations cause loss-of-function by cellular depletion of wolframin.

Functional and mutational characterization of human MIA40 acting during import into the mitochondrial intermembrane space.

A first component involved in import into the mitochondrial intermembrane space, named Mia40, has been described recently in yeast. Here, we identified the human MIA40 as a novel and ubiquitously expressed component of human mitochondria. It belongs to a novel protein family whose members share six highly conserved cysteine residues constituting a -CXC-CX9C-CX9C- motif. Human MIA40 is significantly smaller than the fungal protein and lacks the N-terminal extension including a transmembrane region and mitochondrial targeting signal. It forms soluble complexes within the intermembrane space of human mitochondria. Depletion of MIA40 in human cells by RNA interference specifically affected steady-state levels of small and cysteine-containing intermembrane space proteins like DDP1 and TIM10A, suggesting that MIA40 acts along the import pathway into the intermembrane space. Studies on the in vivo redox state of human MIA40 demonstrated that it contains intramolecular disulfide bonds. Thiol-trapping assays revealed the co-existence of different oxidation states of human MIA40 within the cell. Furthermore, we show that the twin -CX9C- motif is specifically required for import and stability of MIA40 in mitochondria. Partial mutation of this motif affects stable accumulation of MIA40 in the intermembrane space, whereas mutation of all cysteine residues in this motif inhibits import in mitochondria. Taken together, we conclude that the biogenesis and function of MIA40 in the mitochondrial intermembrane space is dependent on redox processes involving conserved cysteine residues.

Appendix carcinoid associated with the Peutz-Jeghers syndrome.

INTRODUCTION: The Peutz-Jeghers syndrome (PJS) is a rare hereditary, autosomal-dominant disorder. It is characterized by a gastrointestinal polyposis and mucocutaneous melanic spots. It has also been reported as a precondition for malignancies with a life-time-hazard for cancer up to 93%, caused by a germline mutation in the STK11 gene. PRESENTATION OF CASE: A 21-year-old man presented with nausea and abdominal pain. He had a known history of PJS since the age of 13 when he was treated for intussusception due to a hamartomatous polyp. Preoperative diagnostics revealed a second intussusception and an extensive intestinal polyposis. Intraoperative findings confirmed the suspected diagnoses and desvagination was performed. Nearly 50 polyps were removed from the small intestinum over several longitudinal sections. As the appendix appeared thickened an appendectomy was performed simultaneously. Histology showed hamartomatous polyps and the incidental finding of a pT1 carcinoid of the appendix. The patient recovered well and needed no further treatment for his carcinoid tumor. DISCUSSION: The mechanism of carcinogenesis in PJS still remains debatable, although the genetic disorder underlying the syndrome is known. A predisposition for carcinoid tumors also stays questionable. To our knowledge there is no description of an association between carcinoid tumors of the appendix and PJS to date. CONCLUSION: Life-expectancy in patients with PJS is reduced. Causes are the development of malignancies and complications from the polyps such as intussusception. Since there is no treatment possible main focus must be aimed at early recognition of malignancies and the prevention of complications.

Traumatic diaphragmatic ruptures: clinical presentation, diagnosis and surgical approach in adults.

OBJECTIVE: Traumatic diaphragmatic injuries are rare, but potentially life-threatening due to herniation of abdominal organs into the pleural cavities. They can be easily overlooked on initial diagnostics and a high index of suspicion is required. The aim of this retrospective study was to analyze the clinical presentation, diagnostic methods and surgical management of patients with diaphragmatic rupture at our institution. METHODS: A retrospective study was performed to analyze our experience with patients suffering from traumatic diaphragmatic rupture. Charts were reviewed for sex, age, side-location, concomitant injuries, time-to-diagnosis, diagnostic methods, surgical approach and outcome. RESULTS: Fourteen patients (median age: 46 yrs, range 18-71, 9 male, 5 female) with diaphragmatic injuries (left side: 10, right side: 4) were treated between July 2003 and September 2011. Mechanism of injury was a penetrating trauma (14%), blunt trauma (50%) and others (36%). Associated abdominal injuries included spleen rupture (n=3), liver laceration (n=2), abdominal wall laceration (n=2) and gastric perforation (n=1). Computed tomography was the most sensitive diagnostic method. All patients underwent trans-abdominal repair of the diaphragmatic defect (direct suture: 10, prosthetic mesh insertion: 4). Associated abdominal procedures included splenectomy (n=3), liver packing (n=2), abdominal wall reconstruction (n=2) and partial gastric resection (n=1). Morbidity and hospital mortality rate were 36% and 0%, respectively. Median postoperative hospital stay was 17 days (range: 7-40 days). CONCLUSION: Morbidity and mortality of diaphragmatic ruptures are mainly determined by associated injuries or complications of diaphragmatic herniation like incarceration of viscera or lung failure. Early diagnosis helps to prevent severe complications. Spiral CT-scan is the most reliable tool for acute diagnosis of diaphragmatic rupture and associated visceral lacerations. Laparotomy is an adequate surgical approach for diaphragmatic repair, especially in cases of associated abdominal organ injury.

Subcomplexes of human ATP synthase mark mitochondrial biosynthesis disorders.

METHODS: We describe biochemically and clinically relevant aspects of mitochondrial ATP synthase, the enzyme that supplies most ATP for the cells energy demand. RESULTS: Analyzing human Rho zero cells we could identify three subcomplexes of ATP synthase: F1 catalytic domain, F1 domain with bound natural IF1 inhibitor protein, and F1-c subcomplex, an assembly of F1 domain and a ring of F(O)-subunits c. Large amounts of F1 subcomplexes accumulated also in mitochondria of patients with specific mitochondrial disorders. By quantifying the F1 subcomplexes and other oxidative phosphorylation complexes in parallel, we were able to discriminate three classes of defects in mitochondrial biosynthesis, namely, mitochondrial DNA depletion, mitochondrial transfer RNA (tRNA) mutations, and mutations in the mitochondrial ATP6 gene. INTERPRETATION: The relatively simple electrophoretic assay used here is a straightforward approach to differentiate between various types of genetic alterations affecting the biosynthesis of oxidative phosphorylation complexes and will be useful to guide molecular genetic diagnostics in the field of mitochondrial neuromuscular disorders.

Wolfram syndrome 1 (WFS1) protein expression in retinal ganglion cells and optic nerve glia of the cynomolgus monkey.

Wolfram syndrome (WFS1, OMIM 222300) is a rare genetic disorder associated with multiple organ abnormalities, most prominently optic nerve atrophy and diabetes. Mutations in the WFS1 gene coding for wolframin have been identified. The pathogenesis for optic nerve atrophy remains elusive. We here tested the hypothesis that wolframin is expressed in glial cells of the optic nerve and in retinal ganglion cells in the cynomolgus monkey. Paraffin sections through the retina and optic nerve were examined with immunohistochemistry using affinity-purified antibodies to wolframin. Retinal ganglion cells and optic nerve glial cells were found to be strongly labeled. Dual dysfunction of wolframin in optic nerve glial cells and retinal ganglion cells may explain the progressive optic nerve atrophy in Wolfram syndrome.

Proteolytic processing of OPA1 links mitochondrial dysfunction to alterations in mitochondrial morphology.

Many muscular and neurological disorders are associated with mitochondrial dysfunction and are often accompanied by changes in mitochondrial morphology. Mutations in the gene encoding OPA1, a protein required for fusion of mitochondria, are associated with hereditary autosomal dominant optic atrophy type I. Here we show that mitochondrial fragmentation correlates with processing of large isoforms of OPA1 in cybrid cells from a patient with myoclonus epilepsy and ragged-red fibers syndrome and in mouse embryonic fibroblasts harboring an error-prone mitochondrial mtDNA polymerase gamma. Furthermore, processed OPA1 was observed in heart tissue derived from heart-specific TFAM knock-out mice suffering from mitochondrial cardiomyopathy and in skeletal muscles from patients suffering from mitochondrial myopathies such as myopathy encephalopathy lactic acidosis and stroke-like episodes. Dissipation of the mitochondrial membrane potential leads to fast induction of proteolytic processing of OPA1 and concomitant fragmentation of mitochondria. Recovery of mitochondrial fusion depended on protein synthesis and was accompanied by resynthesis of large isoforms of OPA1. Fragmentation of mitochondria was prevented by overexpressing OPA1. Taken together, our data indicate that proteolytic processing of OPA1 has a key role in inducing fragmentation of energetically compromised mitochondria. We present the hypothesis that this pathway regulates mitochondrial morphology and serves as an early response to prevent fusion of dysfunctional mitochondria with the functional mitochondrial network.

Organization and function of the small Tim complexes acting along the import pathway of metabolite carriers into mammalian mitochondria.

Tim9, Tim10a, and Tim10b are members of the family of small Tim proteins located in the intermembrane space of mammalian mitochondria. In yeast, members of this family act along the TIM22 import pathway during import of metabolite carriers and other integral inner membrane proteins. Here, we show that the human small proteins form two distinct hetero-oligomeric complexes. A 70-kDa complex that contains Tim9 and Tim10a and a Tim9-10a-10b that is part of a higher molecular weight assembly of 450 kDa. This distribution among two complexes suggests Tim10b to be the functional homologue of yeast Tim12. Both human complexes are tightly associated with the inner membrane and, compared with yeast, soluble 70-kDa complexes appear to be completely absent in the intermembrane space. Thus, the function of soluble 70-kDa complexes as trans-site receptors for incoming carrier proteins is not conserved from lower to higher eukaryotes. During import, the small Tim complexes directly interact with human adenine nucleotide translocator (ANT) in transit in a metal-dependent manner. For insertion of carrier preproteins into the inner membrane, the human small Tim proteins directly interact with human Tim22, the putative insertion pore of the TIM22 translocase. However, in contrast to yeast, only a small fraction of Tim9-Tim10a-Tim10b complex is in a stable association with Tim22. We conclude that different mechanisms and specific requirements for import and insertion of mammalian carrier preproteins have evolved in higher eukaryotes.

The molecular basis of the Rhesus antigen Ew.

BACKGROUND: The Rhesus antigen Ew (ISBT designation 004 011) was first described in 1955. It is defined by a specific antibody, but its molecular genetic basis has not yet been resolved. STUDY DESIGN AND METHODS: Two individuals serologically characterized to express the rare Rhesus antigen Ew were analyzed by sequencing of all 10 exons of the RHCE gene. RESULTS: A nucleotide exchange at position 500 (T500A) resulting in a Met167Lys amino acid substitution was found in both individuals. Moreover, we show that an individual carrying the Ew antigen is capable to produce an alloantibody against the wild-type E antigen. CONCLUSION: The single-point mutation T500A in exon 4 of the RHCE gene is a molecular basis of the rare Rhesus antigen Ew.

Significance of respirasomes for the assembly/stability of human respiratory chain complex I.

We showed that the human respiratory chain is organized in supramolecular assemblies of respiratory chain complexes, the respirasomes. The mitochondrial complexes I (NADH dehydrogenase) and III (cytochrome c reductase) form a stable core respirasome to which complex IV (cytochrome c oxidase) can also bind. An analysis of the state of respirasomes in patients with an isolated deficiency of single complexes provided evidence that the formation of respirasomes is essential for the assembly/stability of complex I, the major entry point of respiratory chain substrates. Genetic alterations leading to a loss of complex III prevented respirasome formation and led to the secondary loss of complex I. Therefore, primary complex III assembly deficiencies presented as combined complex III/I defects. This dependence of complex I assembly/stability on respirasome formation has important implications for the diagnosis of mitochondrial respiratory chain disorders.

Wolfram syndrome: structural and functional analyses of mutant and wild-type wolframin, the WFS1 gene product.

Mutations of the WFS1 gene are responsible for Wolfram syndrome, a rare, recessive disorder characterized by early-onset, non-autoimmune diabetes mellitus, optic atrophy and further neurological and endocrinological abnormalities. The WFS1 gene encodes wolframin, a putative multispanning membrane glycoprotein of the endoplasmic reticulum. The function of wolframin is completely unknown. In order to characterize wolframin, we have generated polyclonal antibodies against both hydrophilic termini of the protein. Wolframin was found to be ubiquitously expressed with highest levels in brain, pancreas, heart and insulinoma beta-cell lines. Analysis of the structural features provides experimental evidence that wolframin contains nine transmembrane segments and is embedded in the membrane in an N(cyt)/C(lum) topology. Wolframin assembles into higher molecular weight complexes of approximately 400 kDa in the membrane. Pulse-chase experiments demonstrate that during maturation wolframin is N-glycosylated but lacks proteolytical processing. Moreover, N-glycosylation appears to be essential for the biogenesis and stability of wolframin. Here we investigate, for the first time, the molecular mechanisms that cause loss-of-function of wolframin in affected individuals. In patients harboring nonsense mutations complete absence of the mutated wolframin is caused by instability and rapid decay of WFS1 nonsense transcripts. In a patient carrying a compound heterozygous missense mutation, R629W, we found markedly reduced steady-state levels of wolframin. Pulse-chase experiments of mutant wolframin expressed in COS-7 cells indicated that the R629W mutation leads to instability and strongly reduced half-life of wolframin. Thus, the Wolfram syndrome in patients investigated here is caused by reduced protein dosage rather than dysfunction of the mutant wolframin.

Tandem mass spectrometric assay for the determination of carnitine palmitoyltransferase II activity in muscle tissue.

Carnitine palmitoyltransferase II (CPT-II) mediates the import of long-chain fatty acids into the mitochondrial matrix for subsequent beta-oxidation. Defects of CPT-II manifest as a severe neonatal hepatocardiomuscular form or as a mild muscular phenotype in early infancy or adolescence. CPT-II deficiency is diagnosed by the determination of enzyme activity in tissues involving the time-dependent conversion of radiolabeled CPT-II substrates (isotope-exchange assays) or the formation of chromogenic reaction products. We have established a mass spectrometric assay (MS/MS) for the determination of CPT-II activity based on the stoichiometric formation of acetylcarnitine in a coupled reaction system. In this single-tube reaction system palmitoylcarnitine is converted by CPT-II to free carnitine, which is subsequently esterified to acetylcarnitine by carnitine acetyltransferase. The formation of acetylcarnitine directly correlates with the CPT-II activity. Comparison of the MS/MS method (y) with our routine spectrophotometric assay (x) revealed a linear regression of y = 0.58x + 0.12 (r = 0.8369). Both assays allow one to unambiguously detect patients with the muscular form of CPT-II deficiency. However, the higher specificity and sensitivity as well as the avoidance of the drawbacks inherent in the use of radiolabeled substrates make this mass spectrometric method most suitable for the determination of CPT-II activity.

The C66W mutation in the deafness dystonia peptide 1 (DDP1) affects the formation of functional DDP1.TIM13 complexes in the mitochondrial intermembrane space.

Mohr-Tranebjaerg syndrome is a progressive, neurodegenerative disorder caused by loss-of-function mutations in the DDP1/TIMM8A gene. DDP1 belongs to a family of evolutionary conserved proteins that are organized in hetero-oligomeric complexes in the mitochondrial intermembrane space. They mediate the import and insertion of hydrophobic membrane proteins into the mitochondrial inner membrane. All of them share a conserved Cys(4) metal binding site proposed to be required for the formation of zinc fingers. So far, the only missense mutation known to cause a full-blown clinical phenotype is a C66W exchange directly affecting this Cys(4) motif. Here, we show that the mutant human protein is efficiently imported into mitochondria and sorted into the intermembrane space. In contrast to wild-type DDP1, it does not complement the function of its yeast homologue Tim8. The C66W mutation impairs binding of Zn(2+) ions via the Cys(4) motif. As a consequence, the mutated DDP1 is incorrectly folded and loses its ability to assemble into a hetero-hexameric 70-kDa complex with its cognate partner protein human Tim13. Thus, an assembly defect of DDP1 is the molecular basis of Mohr-Tranebjaerg syndrome in patients carrying the C66W mutation.

Dystonia in the Mohr-Tranebjaerg syndrome responds to GABAergic substances.

Mutations in the X-linked deafness-dystonia peptide 1 (DDP1) gene cause Mohr-Tranebjaerg syndrome (MTS), a rare form of deafness associated with dystonia. In the patient presented here, improvement of dystonic symptoms upon treatment with alcohol and GABAergic substances is demonstrated for the first time.

Clinical and molecular findings in a patient with a novel mutation in the deafness-dystonia peptide (DDP1) gene.

The Mohr-Tranebjaerg syndrome (MTS) is a rare neurodegenerative disorder characterized by early-onset deafness, dystonia and further neurological abnormalities such as cortical blindness, spasticity, dementia and mental retardation. Causative mutations were identified within the deafness-dystonia peptide (DDP1/TIMM8a) gene on the X-chromosome. The DDP1 protein is located in the intermembrane space of human mitochondria. Here, it acts in a complex together with its partner protein Tim13 in a chaperone-like manner to facilitate the import of nuclear-encoded precursor proteins into the mitochondrial inner membrane. Thus, MTS is a novel type of mitochondrial disorder. To obtain more insight into the pathophysiology of this neurodegenerative disorder, we performed for the first time a comprehensive clinical and functional characterization of a patient suffering from MTS. This patient exhibited a typical combination of deafness, dystonia and visual loss. Sequence analysis of the patient's DDP1 gene revealed a G to C transversion at nucleotide position 38 of the first exon. The mutation affects the ATG start codon, thereby changing methionine to isoleucine (M1I), and leads to a complete absence of the DDP1 protein. In addition, the partner protein Tim13 was found to be significantly reduced, suggesting that Tim13 requires the presence of DDP1 for its stabilization. The assessment of mitochondrial functions showed the enzyme activities of the mitochondrial energy-generating systems to be normal in the muscle biopsy. Structural abnormalities or aggregations of mitochondria were absent. Electron microscopy revealed only a mild neurogenic atrophy. Neurophysiological investigations showed cochlear dysfunction and disturbance of visual pathways. PET and MRI studies revealed a multifocal pattern of neurodegeneration with hypometabolic areas predominantly located over the right striatum and parietal cortex and marked atrophy of the occipital lobes. Although the visual loss is caused predominantly by neurodegeneration of the visual cortex, degeneration of the retina and the optic nerve contributes to the visual impairment. The pathological changes in basal ganglia and sensory cortex demonstrate the disintegration of subcortico-cortical circuits and correlate well with the clinical presentation of multifocal dystonia. The data presented here showed that, in contrast to most of the known mitochondrial disorders, MTS appears not to be associated with a functional defect of the energy generation system of the mitochondria. Whereas the specific mitochondrial dysfunction leading to neuronal loss in MTS remains to be clarified, the electrophysiological and neuroimaging findings allowed the multifocal manifestation of neurodegenerative lesions in MTS to be characterized specifically.