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The m.3243A>G "MELAS" (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) mutation is one of the most common point mutations of the mitochondrial DNA, but its phenotypic variability is incompletely understood. The aim of this study was to revise the phenotypic spectrum associated with the mitochondrial m.3243A>G mutation in 126 Italian carriers of the mutation, by a retrospective, database-based study ("Nation-wide Italian Collaborative Network of Mitochondrial Diseases"). Our results confirmed the high clinical heterogeneity of the m.3243A>G mutation. Hearing loss and diabetes were the most frequent clinical features, followed by stroke-like episodes. "MIDD" (maternally-inherited diabetes and deafness) and "PEO" (progressive external ophthalmoplegia) are nosographic terms without any real prognostic value, because these patients may be even more prone to the development of multisystem complications such as stroke-like episodes and heart involvement. The "MELAS" acronym is convincing and useful to denote patients with histological, biochemical and/or molecular evidence of mitochondrial disease who experience stroke-like episodes. Of note, we observed for the first time that male gender could represent a risk factor for the development of stroke-like episodes in Italian m.3243A>G carriers. Gender effect is not a new concept in mitochondrial medicine, but it has never been observed in MELAS. A better elucidation of the complex network linking mitochondrial dysfunction, apoptosis, estrogen effects and stroke-like episodes may hold therapeutic promises. © 2013 Springer-Verlag Berlin Heidelberg.

Background Pompe’s disease is a progressive myopathy caused by mutations in the lysosomal enzyme acid alphaglucosidase gene (GAA). A wide clinical variability occurs also in patients sharing the same GAA mutations, even within the same family. Methods For a large series of GSDII patients we collected some clinical data as age of onset of the disease, presence or absence of muscular pain, Walton score, 6-Minute Walking Test, Vital Capacity, and Creatine Kinase. DNA was extracted and tested for GAA mutations and some genetic polymorphisms able to influence muscle properties (ACE, ACTN3, AGT and PPARα genes). We compared the polymorphisms analyzed in groups of patients with Pompe disease clustered for their homogeneous genotype. Results We have been able to identify four subgroups of patients completely homogeneous for their genotype, and two groups homogeneous as far as the second mutation is defined “very severe” or “potentially less severe”. When disease free life was studied we observed a high significant difference between groups. The DD genotype in the ACE gene and the XX genotype in the ACTN3 gene were significantly associated to an earlier age of onset of the disease. The ACE DD genotype was also associated to the presence of muscle pain. Conclusions We demonstrate that ACE and ACTN3 polymorphisms are genetic factors able to modulate the clinical phenotype of patients affected with Pompe disease. Electronic supplementary material The online version of this article (doi:10.1186/s13023-014-0102-z) contains supplementary material, which is available to authorized users.

Glycogenosis II (GSDII) is an autosomal recessive lysosomal storage disorder resulting from deficiency of acid alpha-glucosidase and subsequent lysosomal accumulation of glycogen in skeletal, cardiac and smooth muscles. The late-onset form is characterized by wide variability of the phenotypical spectrum. Clinical findings may include muscle weakness, respiratory insufficiency, vascular abnormalities, low bone mineral density and higher risk of developing osteoporosis. Craniovertebral junction (CVJ) malformations have never been described so far. We here report on a GSDII 43-year-old woman who harbored the mutations IVS1-13T>G and c.2237G>A in the acid alpha-glucosidase gene. She recurrently suffered from headache, neck pain and dizziness. Brain MRI and CT scan showed the presence of a very rare complex CVJ malformation composed of basilar invagination, basiocciput hypoplasia, partial C1 assimilation, C1 posterior arch aplasia and C1 lateral mass hypoplasia and offset. Although we cannot rule out their coincidental occurrence, the rarity of multiple CVJ malformations in the general population as well as the well-known GSDII multisystem involvement should suggest to study the CVJ in the diagnostic process of GSDII patients in order to assess the CVJ malformation frequency in GSDII population and verify a possible relationship between these two conditions.

Complicated hereditary spastic paraplegias (HSP) are a heterogeneous group of HSP characterized by spasticity associated with a variable combination of neurologic and extra-neurologic signs and symptoms. Among them, HSP with thin corpus callosum and intellectual disability is a frequent subtype, often inherited as a recessive trait (ARHSP-TCC). Within this heterogeneous subgroup, SPG11 and SPG15 represent the most frequent subtypes. We analyzed the mutation frequency of three genes associated with early-onset forms of ARHSP with and without TCC, CYP2U1/SPG56, DDHD2/SPG54 and GBA2/SPG46, in a large population of selected complicated HSP patients by using a combined approach of traditional-based and amplicon-based high-throughput pooled-sequencing. Three families with mutations were identified, one for each of the genes analyzed. Novel homozygous mutations were identified in CYP2U1 (c.1A>C/p.Met1?) and in GBA2 (c.2048G>C/p.Gly683Arg), while the homozygous mutation found in DDHD2 (c.1978G>C/p.Asp660His) had been previously reported in a compound heterozygous state. The phenotypes associated with the CYP2U1 and DDHD2 mutations overlap the SPG56 and the SPG54 subtypes, respectively, with few differences. By contrast, the GBA2 mutated patients show phenotypes combining typical features of both the SPG46 subtype and the recessive ataxia form, with marked intrafamilial variability thereby expanding the spectrum of clinical entities associated with GBA2 mutations. Overall, each of three genes analyzed shows a low mutation frequency in a general population of complicated HSP (

We describe a new mutation in the tRNA(Ala) gene, a T-->C transition at nucleotide position 5628, in a 62-year-old woman with late onset chronic progressive external ophthalmoplegia, dysphagia and mild proximal myopathy. The mutation is heteroplasmic and disrupts a highly conserved A-U base pair within the anticodon stem of the tRNA(Ala). Cytochrome c oxidase-negative fibers harbor a significantly higher level of mutated mtDNA than cytochrome c oxidase-positive fibers. This is the first mutation in the tRNA(Ala) gene which satisfies accepted criteria for pathogenicity.

Identification of mutations at familial loci for amyotrophic lateral sclerosis (ALS) has provided novel insights into the aetiology of this rapidly progressing fatal neurodegenerative disease. However, genome-wide association studies (GWAS) of the more common (∼90%) sporadic form have been less successful with the exception of the replicated locus at 9p21.2. To identify new loci associated with disease susceptibility, we have established the largest association study in ALS to date and undertaken a GWAS meta-analytical study combining 3959 newly genotyped Italian individuals (1982 cases and 1977 controls) collected by SLAGEN (Italian Consortium for the Genetics of ALS) together with samples from Netherlands, USA, UK, Sweden, Belgium, France, Ireland and Italy collected by ALSGEN (the International Consortium on Amyotrophic Lateral Sclerosis Genetics). We analysed a total of 13 225 individuals, 6100 cases and 7125 controls for almost 7 million single-nucleotide polymorphisms (SNPs). We identified a novel locus with genome-wide significance at 17q11.2 (rs34517613 with P = 1.11 × 10(-8); OR 0.82) that was validated when combined with genotype data from a replication cohort (P = 8.62 × 10(-9); OR 0.833) of 4656 individuals. Furthermore, we confirmed the previously reported association at 9p21.2 (rs3849943 with P = 7.69 × 10(-9); OR 1.16). Finally, we estimated the contribution of common variation to heritability of sporadic ALS as ∼12% using a linear mixed model accounting for all SNPs. Our results provide an insight into the genetic structure of sporadic ALS, confirming that common variation contributes to risk and that sufficiently powered studies can identify novel susceptibility loci.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive metabolic disorder caused by a deficiency of thymidine phosphorylase (TP, EC2.4.2.4) due to mutations in the nuclear gene TYMP. TP deficiency leads to plasma and tissue accumulations of thymidine and deoxyuridine which generate imbalances within the mitochondrial nucleotide pools, ultimately leading to mitochondrial dysfunction.1 MNGIE is characterized clinically by leukoencephalopathy, external ophthalmoplegia, peripheral polyneuropathy, cachexia, and enteric neuromyopathy manifesting as gastrointestinal dysmotility. The condition is relentlessly progressive, with patients usually dying from a combination of nutritional and neuromuscular failure at an average age of 37 years.2 Allogeneic hematopoietic stem cell transplantation (AHSCT) offers a permanent cure. Clinical and biochemical improvements following AHSCT have been reported but it carries a high mortality risk and is limited by matched donor availability.3 A consensus proposal for standardizing AHSCT recommends treatment of patients without irreversible end-stage disease and with an optimally matched donor; a majority of patients are ineligible and thus there is a critical requirement for an alternative treatment.4

Disulfiram may cause a peripheral neuropathy that is considered dose- and duration-of-exposure-related. Axonal degeneration has been described as a pathological hallmark of disulfiram toxicity, but experiments have reported a primary toxic effect of the molecule on Schwann cells and myelin.Case 1: At the end of two months of treatment with disulfiram 250 mg/day, a 31-year-old woman complained of weakness in distal segments of the lower limbs associated with burning dysesthesias, numbness and pain in the soles of the feet and the legs below the knees; bilateral walking steppage, reduction in foot strength, absence of ankle jerk and knee tendon reflexes, and tactile stocking pin-pick and vibratory sensory impairment in the lower limbs below the knee. Disulfiram was discontinued and she recovered partially over three months. Case 2: After one month of treatment with disulfiram 1600 mg/day, a 27-year-old man reported walking impairment, distal lower limb weakness and paresthesias. He had unsteady gait with bilateral steppage and foot drop, absence of ankle jerks and overall sensation impairment below the knee. Disulfiram was discontinued and nine months later there was almost complete recovery of motor deficits, only minor motor weakness in distal leg muscles, and no dysesthesia, sensation deficits or areflexia. In both of them clinical and neurophysiological patterns were indicative of a distal axonopathy. DISCUSSION The mechanisms by which disulfiram cause injury in human nerves are unclear, though may involve carbon disulfide. The discrepancy between experimental and clinical observations is still unexplained.We report two cases of disulfiram axonal toxicity and the partial response following discontinuation of the drug.

sporadic motor neuron disorder that differs from the spinal ALS because it remains largely restricted to the upper limbs over time. Only a few cases are described in the literature with a follow-up ranging between two and 11 years (3,4). We report on a 69-years-old patient having a 35-year history of progressive bilateral weakness of the proximal segments of upper limbs and shoulders, which started insidiously on the left side and involved the right side 15 years later. No lower limb involve-ment was reported. No injury of rotator cuff muscles and tendons was noted. Neuromuscular family history was unremarkable. Clinical evaluation showed severe weakness and atrophy of muscles of the upper limb girdle (Figure 1). Distal segments of upper limbs as well as lower limbs were normal. Fasciculations were not present. Deep tendon refl exes were absent at the upper limbs and normal at the lower ones. Dear Sir, Man-in-the-barrel syndrome (MIBS) is characterized by brachial diplegia with motor function preserved in the legs and facial musculature, giving to a patient the clinical appearance of seeming constrained in a barrel (1). MIBS was early observed in patients with bilat-eral ischaemia in the border zones of the anterior and medial cerebral arteries, pontine lesion, multiple sclerosis lesions, cerebral metastases and head trauma. A less recognized variant of MIBS is the neurogenic form that can result from different causes, i.e. amyotrophic lateral sclerosis and myelopathies with purely motor presentation including cervical spinal cord infarction, cervical spondylosis and post radiation (1,2). The term ‘ brachial amyotrophic diplegia ’ has been used to identify a MIBS related to a primary

s S37 patients at the time of their fi rst infusion has decreased from 53 years in group 1 to 50 years in group 2.

The treatment of progressive myoclonic epilepsy (PME) is largely empirical, even though valproic acid (VPA) is usually considered the drug of first choice. However, VPA should be used with caution in PME due to mitochondrial dysfunction, i.e. in MERRF (myoclonic epilepsy with ragged red fibers) syndrome, because of its interaction with mitochondrial respiration and metabolism. Levetiracetam (LEV) treatment was started in combination with VPA in a patient with typical clinical, histological, and biochemical features of MERRF due to a mutation on the tRNA of Phenilalanine gene. The average myoclonus score improved dramatically, as well as the quality of life and no side effects were observed, even after having withdrawn VPA. LEV may benefit myoclonus in PME of mitochondrial origin without altering mitochondrial function, and it could be considered the drug of first choice for the treatment of myoclonus in MERRF.

Glycogenosis type II (OMIM 23230) is an autosomal recessive lysosomal storage disorder resulting from a deficiency in the glucosidase alpha acid (GAA) enzyme. The disease is characterized by progressive accumulation of lysosomal glycogen in various tissues, primarily heart and skeletal muscle, and it is clinically classified into three forms: infantile, juvenile, and late-onset. The histopathological hallmarks in muscle tissue are fiber vacuolization and autophagy. Recombinant human GAA is the only approved enzyme replacement therapy (ERT) available for disease treatment. It is effective in most infantile patients, whereas the improvement is quite variable in adults. We analyzed muscle biopsies from 14 late-onset patients at molecular, biochemical, and histopathological level before and after ERT. We evaluated the following morphological parameters: CSA, number of vacuolated fibers, degree of glycogen accumulation, percentage of vacuolization in type I and II fibers. Pre-treatment muscle biopsies showed marked histopathological variability ranging from almost normal morphology to severe vacuolar myopathy. Post-treatment muscle biopsies morphologically improved in seven patients, worsened in two patients and were unchanged in all the other subjects. Immunohistochemical analysis of the autophagic/lysosomal markers EEA1 (early endosome antigen 1), LC3 (microtubule-associated protein 1 light chain 3), and LAMP2 (lysosome associated membrane protein 2) showed a variable binding in both the first and the second biopsies. GAA enzymatic activity, tested by a fluorimetric assay in both lymphocytes and muscle tissue from 5 patients after ERT, was mildly increased in skeletal muscle compared with pre-treatment levels. Also, GAA expression assessed by immunoblotting slightly increased in a few patients. All patients clinically improved or remained stable after ERT.

Skeletal muscle channelopathies are rare diseases, including non-dystrophic myotonia and periodic paralysis, which are associated with a great inter- and intrafamilial phenotypic variability, making challenging genotype-phenotype correlations. Hence studies on large populations of patients are needed. We included patients referred to Carlo Besta Neurological Institute molecular laboratory with a clinical diagnosis of periodic paralysis or nondystrophic myotonia and mutated in CLCN1, SCN4A, KCNJ2 or CACNA1S. We investigated 301 patients, among which 195 (64.3%) patients mutated in CLCN1 gene, 74 (24.6%) in SCN4A, 28 (9.3%) in CACNA1S and 4 (1.3%) in KCNJ2. We found 22 novel mutations: 8 in CLCN1 gene, 13 in SCN4A and 1 in CACNA1S. All the mutations detected in SCN4A, CACNA1S and KCNJ2 genes were missense, except for an unreported 9-nucleotide deletion in SCN4A. On the contrary CLCN1mutations were missense in 131/195 (67.2%) patients and remaining cases showed nonsense, splice site or deletion mutations. Our study confirms genetic heterogeneity of muscle channelopathies, although a relatively small number of mutations is responsible for most of the cases.

BackgroundDegeneration of intraepidermal nerve fibers (IENF) is a hallmark of small fiber neuropathy of different etiology, whose clinical picture is dominated by neuropathic pain. It is unknown if critical illness can affect IENF.MethodsWe enrolled 14 adult neurocritical care patients with prolonged intensive care unit (ICU) stay and artificial ventilation (≥ 3 days), and no previous history or risk factors for neuromuscular disease. All patients underwent neurological examination including evaluation of consciousness, sensory functions, muscle strength, nerve conduction study and needle electromyography, autonomic dysfunction using the finger wrinkling test, and skin biopsy for quantification of IENF and sweat gland innervation density during ICU stay and at follow-up visit. Development of infection, sepsis and multiple organ failure was recorded throughout the ICU stay.ResultsOf the 14 patients recruited, 13 (93%) had infections, sepsis or multiple organ failure. All had severe and non-length dependent loss of IENF. Sweat gland innervation was reduced in all except one patient. Of the 7 patients available for follow-up visit, three complained of diffuse sensory loss and burning pain, and another three showed clinical dysautonomia.ConclusionsSmall fiber pathology can develop in the acute phase of critical illness and may explain chronic sensory impairment and pain in neurocritical care survivors. Its impact on long term disability warrants further studies involving also non-neurologic critical care patients.

Facioscapulohumeral muscular dystrophy has been genetically linked to reduced numbers (≤ 8) of D4Z4 repeats at 4q35 combined with 4A(159/161/168) DUX4 polyadenylation signal haplotype. However, we have recently reported that 1.3% of healthy individuals carry this molecular signature and 19% of subjects affected by facioscapulohumeral muscular dystrophy do not carry alleles with eight or fewer D4Z4 repeats. Therefore, prognosis for subjects carrying or at risk of carrying D4Z4 reduced alleles has become more complicated. To test for additional prognostic factors, we measured the degree of motor impairment in a large group of patients affected by facioscapulohumeral muscular dystrophy and their relatives who are carrying D4Z4 reduced alleles. The clinical expression of motor impairment was assessed in 530 subjects, 163 probands and 367 relatives, from 176 unrelated families according to a standardized clinical score. The associations between clinical severity and size of D4Z4 allele, degree of kinship, gender, age and 4q haplotype were evaluated. Overall, 32.2% of relatives did not display any muscle functional impairment. This phenotype was influenced by the degree of relation with proband, because 47.1% of second- through fifth-degree relatives were unaffected, whereas only 27.5% of first-degree family members did not show motor impairment. The estimated risk of developing motor impairment by age 50 for relatives carrying a D4Z4 reduced allele with 1-3 repeats or 4-8 repeats was 88.7% and 55%, respectively. Male relatives had a mean score significantly higher than females (5.4 versus 4.0, P = 0.003). No 4q haplotype was exclusively associated with the presence of disease. In 13% of families in which D4Z4 alleles with 4-8 repeats segregate, the diagnosis of facioscapulohumeral muscular dystrophy was reported only in one generation. In conclusion, this large-scale analysis provides further information that should be taken into account when counselling families in which a reduced allele with 4-8 D4Z4 repeats segregates. In addition, the reduced expression of disease observed in distant relatives suggests that a family's genetic background plays a role in the occurrence of facioscapulohumeral muscular dystrophy. These results indicate that the identification of new susceptibility factors for this disease will require an accurate classification of families.

The authors identified two novel heterozygous missense transitions in the gene for the mitochondrial polymerase gammaA subunit (POLG) in a family with an autosomal recessive syndrome comprising progressive external ophthalmoplegia (PEO), polyneuropathy, ataxia, sensorineural hearing loss, and affective disorders. These mutations were not detected in 120 healthy control subjects.

We describe a case of an adult male patient with progressive external ophthalmoplegia and upper limb weakness, who presented with an episode of sudden respiratory failure. Muscle biopsy showed ragged-red and COX-negative fibers associated with discrete inflammatory infiltrates and necrotizing features. Apart from artificial ventilator support, he was treated with intravenous immunoglobulins and carnitine, with excellent clinical outcome. Mitochondrial DNA analysis revealed the 3251A>G mutation, previously reported in association with rapidly progressive mitochondrial myopathy and respiratory failure. Our case expands the spectrum of this mutation and suggests a therapeutic attempt with immunoglobulins in mitochondrial patients with acute respiratory failure, at least when this mutation and/or muscle inflammation is present. Moreover, this case supports the idea of a pathologic inflammatory response induced by mitochondrial disease; such an abnormal response may be a contributory factor in disease progression or acute exacerbation typical of some mitochondrial diseases, but further studies are needed.

Paraproteinemic neuropathy (PPN) is often under-diagnosed because of its clinical and electrophysiological variability. Progression of neuropathy is considered an alarm bell for possible malignant conversion of underlying monoclonal gammopathy (MG).To report clinical presentation, course, and evolution in a group of patients with PPN in order to identify findings useful for achieving the diagnosis, suspecting progression, and recognizing the underlying hematological conditions.Thirty-nine patients with PPN underwent clinical examination, electrodiagnostic studies, cerebrospinal fluid analysis, and laboratory tests. These parameters were compared between the different peak groups.IgM MG was found in 51.4%, IgG MG in 33.3%, and IgA MG in 10.3% of our cohort. PPN appeared as mainly sensory, demyelinating, mildly progressive neuropathy, regardless of the type of peak or light chain. However, axonal findings were present in many IgG patients and in part of the IgM patients and a small number of the IgG patients may have presented with motor symptoms at the onset. The IgM patients had a significant tendency toward clinical worsening and IgG subjects had a more elevated rate of malignancy. IgA-related neuropathies were rare, heterogenous, and with a high tendency to evolution and malignancy.Most of PPN often present a relatively monomorphic clinical picture but they can be clinically heterogenous and must be suspected even if sensory impairment and demyelination are not the dominant features. Tendency to malignancy seems globally elevated and needs intensive follow-up. Diagnostic approach to patients presenting with peripheral neuropathy should always include the typing of monoclonal immunoglobulins in serum and urine. In contrast, patients presenting with MG should be submitted to nerve conduction study/electroneurography and neurological evaluation.

In 2002, paternal inheritance of muscle mitochondrial DNA (mtDNA) was reported in a patient with exercise intolerance and a mitochondrial DNA (mtDNA) mutation restricted to skeletal muscle. To evaluate whether paternal inheritance is a common phenomenon, we studied 10 sporadic patients with skeletal muscle-restricted mtDNA mutations: five harbored mtDNA point mutations in protein-coding genes and five had single mtDNA deletions. We performed haplotype analysis and direct sequencing of the hypervariable regions 1 and 2 of the D-loop in muscle and blood from the patients and, when available, in blood from their parents. We did not observe paternal inheritance in any of our patients.

Here we describe the imaging findings in a 73-year-old woman who had pain in the right inguinal region, followed by progressive weakness of muscles innervated by the right femoral and obturator nerves, diagnosed as nondiabetic lumbosacral radiculoplexus neuropathy. Magnetic resonance neurography showed thickening and increase in signal intensity of the right femoral and obturator nerves.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). Allogeneic hematopoietic stem cell transplantation (HSCT) has been proposed as a treatment for patients with MNGIE and a standardized approach to HSCT in this condition has recently been developed. We report on the transplant course, management and short-term follow-up in two MNGIE patients who underwent HSCT. The source of stem cells was bone marrow taken from an HLA 9/10 allele-matched unrelated donor in the first patient and from an HLA 10/10 allele-matched sibling donor in the second. Both patients achieved full donor chimerism, and we observed restoration of buffy coat TP activity and lowered urine nucleoside concentrations in both of them. The post-transplant clinical follow-up showed improvement in gastrointestinal dysmotility, abdominal cramps and diarrhea. Neurological assessment remained unchanged. However, the first patient died 15 months after HSCT due to gastrointestinal obstruction and shock; the second patient died 8 months after the procedure due to respiratory distress following septic shock. Although HSCT corrects biochemical abnormalities and improves gastrointestinal symptoms, the procedure can be risky in subjects already in poor medical condition as are many MNGIE patients. Since transplant-related morbidity and mortality increases with progression of the disease and number of comorbidities, MNGIE patients should be submitted to HSCT when they are still relatively healthy, in order to minimize the complications of the procedure. Anyway, there is still incomplete knowledge on the natural history of the disease in many affected patients and it is not yet clear when the best time to do a transplant is. Further clues to the therapeutic potential of HSCT could result from a prolonged observation in a greater number of non-transplanted and transplanted patients, which would allow us to answer the questions of if, how and when MNGIE patients require HSCT treatment.

Mitochondrial disorders are a group of metabolic conditions caused by impairment of the oxidative phosphorylation system. The treatment of mitochondrial diseases is still inadequate. Therapies that have been attempted include: respiratory chain cofactors, other metabolites secondarily decreased in mitochondrial disorders, antioxidants, and agents acting on lactic acidosis. However, their role in the treatment of the majority of mitochondrial diseases is still unclear. Furthermore, some drugs may potentially have detrimental effects on mitochondrial dysfunction.To critically review this still unclear field, this paper attempts to answer, on the basis of the basic and clinical literature available to date, the 'frequently asked questions', such as: Is valproic acid safe in mitochondrial patients? What about other antiepileptic drugs? May metformin trigger lactic acidosis in mitochondrial patients? Are statins safe in these subjects?Randomized clinical trials are necessary to establish efficacy and safety of drugs. Multicenter collaboration is essential for the advancement of therapy for mitochondrial disorders.

Hearing impairment is common in patients with mitochondrial disorders, affecting over half of all cases at some time in the course of the disease. In some patients, deafness is only part of a multisystem disorder. By contrast, there are also a number of “pure” mitochondrial deafness disorders, the most common probably being maternally inherited. We retrospectively analyzed the last 60 genetically confirmed mitochondrial disorders diagnosed in our Department: 28 had bilateral sensorineural hearing loss, whereas 32 didn't present ear's abnormalities, without difference about sex and age of onset between each single group of diseases. We reported also a case of MELAS patient with sensorineural hearing loss, in which cochlear implantation greatly contributed to the patient's quality of life. Our study suggests that sensorineural hearing loss is an important feature in mitochondrial disorders and indicated that cochlear implantation can be recommended for patients with MELAS syndrome and others mitochondrial disorders.

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a rare autosomal recessively inherited disorder of fatty acid metabolism due to ETFA, ETFB or ETFDH mutations. Riboflavin treatment ameliorates symptoms and metabolic profile in ETFDH-related MADD patients. We report on a 20-year-old boy with an 8-year history of progressive difficulty in walking, running and climbing stairs. Muscle biopsy showed a lipid myopathy and the acylcarnitine profile analysis was suggestive of MADD. Nevertheless, no evidence of molecular defects in the ETFA, ETFB and ETFDH exons or intron–exon boundaries was found. Treatment with riboflavin for 1 year resulted in a clear improvement in motor functions. Our report shows that some cases of MADD are not linked to ETFA, ETFB and ETFDH exon or intron–exon boundary changes. They could be due to quite rare promoter or deep intronic mutations or, most likely, to some unknown genetic defect. We therefore suggest to extend in these cases molecular studies to cDNA analysis and indicate the need of extensive pedigree studies to identify other possible disease-related loci. Most important, treatment of these cases with riboflavin can also be effective. Therefore, early diagnosis is essential to achieve the best treatment response.

POEMS (polyneuropathy, organomegaly, endocrinopathy, Mrotein and skin changes) syndrome is a rare cause of mixed emyelinating and axonal neuropathy with multi-organ involveent and a monoclonal plasma cell proliferative disorder [1]. ther important traits of the syndrome are sclerotic bone lesions, astleman disease, papilledema, peripheral edema, ascites, effuions, thrombocytosis, polycythemia, clubbing and increased level f the plasmacytomas-secreted vascular endothelial growth factor VEGF) [1]. The pathogenesis is not well understood but a role for VEGF has een suggested [2]. POEMS syndrome is a potentially fatal disease and patients’ uality of life deteriorates because of progressive neuropathy,masive pleural effusion, ascites or thromboembolic events. Cerebral vasculitis, multiple vascular abnormalities, hyperrophic cranial pachymeningitis, bilateral internal carotid rtery occlusion, amyloidosis, diffuse white matter edema and apilledema have been associated with POEMS syndrome [3–8]. n one case, cranial magnetic resonance imaging disclosed diffuse

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase and is characterized by external ophthalmoparesis, gastrointestinal dysmotility, leukoencephalopathy, and neuropathy. The availability of new therapeutic options (peritoneal dialysis, allogeneic stem cell transplantation, enzyme replacement) makes it necessary to diagnose the disease early, which is not always achieved due to the difficulty in recognizing this disorder, especially in case of atypical presentation. We describe three MNGIE patients with atypical onset of the disease. In the first patient the main symptoms were long-standing chronic fever, recurrent acute migrant arthritis, and gastrointestinal disorders mimicking autoimmune or inflammatory intestinal diseases; the second patient complained only of exercise intolerance and muscle cramps, and the third patient had a CIDP-like polyneuropathy. This study stresses the insidious heterogeneous clinical onset of some cases of MNGIE, expands the spectrum of the phenotype, and suggests considering MNGIE in the differential diagnosis of enteropathic arthritis, isolated exercise intolerance, and inflammatory polyneuropathies not responsive to the usual treatment. A better understanding of the clinical heterogeneity of MNGIE is necessary in order to diagnose atypical cases and promote early diagnosis, which is now absolutely necessary in view of the new available therapies.

The limb-girdle muscular dystrophies are a genetically and clinically heterogeneous group of diseases. Most of these proteinopathies show wide inter- and intrafamilial phenotypic heterogeneity, so that limb-girdle involvement may be often considered as one of the possible clinical expressions of a determined protein defect.This review reports an updated and comprehensive classification of these proteinopathies according to protein defect and transmission modality and focuses on the main associated clinical pictures.An accurate diagnosis is often difficult because of the clinical and genetic variability characterizing this group of muscle diseases. Appropriate diagnostic approaches are essential to achieve the correct diagnosis.

Mitochondrial diseases (MD) are disorders caused by an impairment of the mitochondrial respiratory chain function. They are usually progressive, isolated or multi-system diseases and have variable times of onset. Because mitochondria have their own DNA (mtDNA), MD can be caused by mutations in both mtDNA and nuclear DNA (nDNA). The complexity of genetic control of mitochondrial function is in part responsible for the intra- and inter-familiar clinical heterogeneity of this class of diseases. Despite the remarkable progress in understanding of the molecular bases of these disorders, therapy of MD is quite inadequate. Present options of treatment mainly include physical, pharmacological and gene therapy approaches. Aerobic exercise and physical therapy is useful to prevent or correct deconditioning and may improve exercise tolerance. Pharmacological approach is based on removing noxious metabolites, using reactive oxygen species scavengers and administrating vitamins and cofactors which is especially important in case of primary deficiencies of specific compounds such as Coenzyme Q10. Gene therapy is fascinating but it is difficult to apply because of polyplasmy and heteroplasmy. Experimental methods include gene shifting, allotopic expression, mitochondrial transfection or correcting mtDNA mutations with specific restriction endonucleases. Here, we discussed some recent patents. Progresses in each of these fields may open interesting perspectives for the future.

Glycogen storage disease type II (GSDII) is an autosomal recessive lysosomal disorder caused by mutations in the gene encoding alpha-glucosidase (GAA). The disease can be clinically classified into three types: a severe infantile form, a juvenile and an adult-onset form. Cases with juvenile or adult onset GSDII mimic limb-girdle muscular dystrophy or polymyositis and are often characterized by respiratory involvement. GSDII patients are diagnosed by biochemical assay and by molecular characterization of the GAA gene. Ascertaining a natural history of patients with heterogeneous late-onset GSDII is useful for evaluating their progressive functional disability. A significant decline is observed over the years in skeletal and respiratory muscle function. Enzyme replacement therapy (ERT) has provided encouraging results in the infantile form. It is not yet known if ERT is effective in late-onset GSDII. We examined a series of 11 patients before and after ERT evaluating muscle strength by MRC, timed and graded functional tests, 6-minute walk test (6MWT), respiratory function by spirometric parameters and quality of life. We observed a partial improvement during a prolonged follow-up from 3 to 18 months. The use of different clinical parameters in the proposed protocol seems crucial to determine the efficacy of ERT, since not all late-onset patients respond similarly to ERT.

Mitochondrial disorders (MDs) are caused by impairment of the mitochondrial electron transport chain (ETC). The ETC is needed for oxidative phosphorylation, which provides the cell with the most efficient energy outcome in terms of ATP production. One of the pathogenic mechanisms of MDs is the accumulation of reactive oxygen species. Mitochondrial dysfunction and oxidative stress appear to also have a strong impact on the pathogenesis of neurodegenerative diseases and cancer. The treatment of MDs is still inadequate. Therapies that have been attempted include ETC cofactors, other metabolites secondarily decreased in MDs, antioxidants, and agents acting on lactic acidosis. However, the role of these dietary supplements in the treatment of the majority of MDs remains unclear. This article reviews the rationale for their use and their role in clinical practice in the context of MDs and other disorders involving mitochondrial dysfunction.

Hypocomplementemic urticarial vasculitis (HUV) is a rare form of cutaneous small-vessel vasculitis characterized by recurrent episodes of urticaria and painful, tender, burning or itchy skin lesions, often associated with extracutaneous involvement but usually with no significant peripheral nerve damage. We describe a patient with an HUV of undetermined cause that developed a progressive multifocal sensory neuropathy whose symptoms were temporarily relieved by intravenous immunoglobulin treatment. Sural nerve biopsy showed asymmetrical multifocal nerve fiber loss and axon degeneration in nerve fascicles, a picture suggestive of ischemic damage as a likely result of a vasculitic process. We point out that an axonal neuropathy may complicate idiopathic HUV and suggest looking for peripheral nerve involvement in HUV patients.

Various lines of evidence demonstrate the involvement of mitochondrial dysfunction in the pathogenesis of Huntington's disease (HD). However, the precise role of mitochondria in the neurodegenerative cascade leading to HD is still unclear. Mitochondrial DNA (mtDNA) haplogroups-specific polymorphisms were previously related to several neurodegenerative diseases. The length of CAG repeat seems to be related to the clinical features of HD, such as age of onset and progression of motor impairment. The basis for the impaired cognitive functions and for the mood changes is less clear. Aim of this study was to determine whether mtDNA polymorphism(s) play the role of “modifier gene(s)” in this disease. In this work we have genotyped predefined European mtDNA haplogroups in 51 patients with HD and 181 matched controls. The frequency of the haplogroups and haplogroup clusters did not differ between the two groups, and no correlation with gender, age of onset and disease status was observed. No significant difference was observed between different haplogroups and haplogroup clusters in the cognitive or motor progression of the disease. Our study does not support any association between mtDNA haplogroups and HD.

Background Psychiatric problems, including bipolar affective disorder (BD) and schizophrenia, are common in mitochondrial diseases (MD) and frequently precede the diagnosis of mitochondrial dysfunction. However, they are rarely the only persistent manifestation of a MD and they are usually associated with other neurological or non-neurological features. Case report Here, we describe an Italian family with multiple deletions of mtDNA in muscle, in which BD, schizophrenia, and depression recurred over several generations in the absence of other major signs of mitochondrial dysfunction. Conclusion In patients with positive family history of psychiatric problems, the possibility of MD should be kept in mind, even in absence of other canonical features of mitochondrial encephalomyopathies.

Point mutations in mtDNA-encoded tRNA genes frequently cause isolated myopathies but rarely cause the facioscapulohumeral phenotype. We report on a patient affected with chronic progressive weakness of facioscapulohumeral/peroneal muscles whose muscle biopsy showed a mitochondrial myopathy. mtDNA direct sequencing and RFLP analysis revealed a heteroplasmic transition T12313C which disrupts a conserved site in the TΨC stem of the tRNALeu(CUN) gene and fulfills the accepted criteria of pathogenicity. A partial deletion of the nuclear DNA D4Z4 region with residual repeat sizes of 25 kb was also found in the patient and in her mother. This is the first reported case of mitochondrial myopathy/facioscapulohumeral muscular dystrophy (FSHD) “double trouble”.

Mitochondrial diseases are disorders caused by impairment of the mitochondrial respiratory chain, characterized by clinical-genetic heterogeneity and frequent multisystemic involvement. It is difficult to establish a precise genotype/phenotype correlation and obtain a definitive nosology. Today's genetic classification distinguishes disorders caused by defects in the mitochondrial genome (sporadic or maternally-inherited) from disorders caused by defects in the nuclear genome (autosomally-inherited). We report an updated classification, briefly review the main clinical syndromes and describe the most recent genetic knowledge.

Objective: To evaluate the muscle biopsy findings from 240 patients who had isolated muscle pain. Methods: Histopathology, immunohistochemistry for dystrophin, dystrophin-related proteins, major histocompatibility complex type I, and biochemical analysis of glycolytic and mitochondrial respiratory chain enzymes were performed on muscle biopsies. An attempt was made to correlate pathologic data and clinical findings (sex, age, quality and distribution of symptoms, serum CK levels, and EMG recording). Results: We have described five groups of patients based on muscle biopsy findings: 51.6% had heterogeneous myopathic abnormalities; only 19% of them had a specific myopathic picture, i.e., central nuclei myopathy, central core disease, myopathy with tubular aggregates or with trabecular fibers or abnormalities of fiber typing; 20% had signs of respiratory chain dysfunction but only one patient had a probable mitochondrial disease; 7% had a neurogenic pattern; 2.4% had a metabolic myopathy (phosphorylase or phosphofructokinase deficiency); and 19% had normal muscle biopsy. No clear-cut correlation between muscle biopsy and clinical data was observed except for those patients with a metabolic myopathy. Conclusions: The probability that a patient complaining only of muscle pain and with a normal neurologic examination has a definite muscle pathology is 2%. Only patients with sole exercise-related muscle pain and sCK seven times higher than the normal value are strongly suspected of having a metabolic myopathy. A rigorous selection of patients is needed before performing a muscle biopsy.

Acquired isolated unilateral or bilateral blepharoptosis has many aetiologies. When the pupils are normal, a myasthenic syndrome or myopathy has to be ruled out. If the tests for myasthenia gravis are negative, the next step is to perform a muscle biopsy to establish a diagnosis. Muscle examination may show a mitochondrial disorder, non-specific abnormalities or be quite normal. We identified three patients, who had previously undergone various investigations, including a muscle biopsy, whose lid ptosis disappeared using eye drops containing naphazoline nitrate, a sympathomimetic drug, thus suggesting partial Horner's syndrome. We emphasise the usefulness of this simple and cheap test before performing more traumatic and expensive investigations.

We report a patient with myoclonic epilepsy who underwent muscle biopsy for suspected mitochondrial disease (myoclonic epilepsy with ragged-red fibers, MERRF). In spite of normal histochemical studies and of the absence of a severe COX deficiency, the molecular analysis showed the common MERRF mutation (A8344G) in the tRNA(Lys) gene on mitochondrial DNA. The case serves to illustrate the importance of pursuing the proposed mitochondrial genetic abnormality, even in patients with normal biopsy findings.

Deficiency of the muscle isozyme of glycogen phosphorylase is causative of McArdle disease or Glycogen storage disease type V (GSD-V), the most common autosomal recessive disorder of glycogen metabolism. The typical clinical presentation is characterized by exercise intolerance with cramps, and recurrent myoglobinuria. To date, 46 mutations in the PYGM gene have been detected in GSD-V patients. We report the mutational spectrum in 68 Italian patients. We identified 30 different mutations in the PYGM gene, including 19 mutations that have not been reported previously. The novel mutations include: eight missense mutations (c.475G>A, p.G159R; c.689C>G, p.P230R; c.1094C>T, p.A365E; c.1151C>A, p.A384D; c.1182C>T, p.R428C; c.1471C>T, p.R491C; c.2444A>C, p.D815A; c.2477G>C, p.W826S), two nonsense mutations (c.1475G>A, p.W492X; c.1627A>T, p.K543X), five splice site mutations (c.855 +1G>C; c.1092 +1G>A; c. 1093-1G>T; c.1239 +1G>A; c.2380 +1G>A), and four deletions (c.715_717delGTC, p.V239del; c.304delA, p.N102DfsX4; c.1970_2177del, p.V657_G726; c.2113_2114delGG, p.G705RfsX16). Whereas we confirmed lack of direct correlation between the clinical phenotype and the genotype, we also found that the so-called ‘common mutation’ (p.R50X) accounted for about 43% of alleles in our cohort and that no population-related mutations are clearly identified in Italian patients. © 2006 Wiley-Liss, Inc.

We studied nine infant patients with a combination of progressive neurological and hepatic failure. Eight children, including two sibling pairs and four singletons, were affected by Alpers' hepatopathic poliodystrophy. A ninth baby patient suffered of a severe floppy infant syndrome associated with liver failure. Analysis of POLG1, the gene encoding the catalytic subunit of mitochondrial DNA polymerase, revealed that all the patients carried different allelic mutations in this gene. POLG1 is a major disease gene in mitochondrial disorders. Mutations in this gene can be associated with multiple deletions, depletion or point mutations of mitochondrial DNA (mtDNA). In turn, these different molecular phenotypes dictate an extremely heterogeneous spectrum of clinical outcomes, ranging from adult-onset progressive ophthalmoplegia to juvenile ataxic syndromes with epilepsy, to rapidly fatal hepatocerebral presentations, including Alpers' syndrome.

Sarcoplasmic masses contain disorganized myofibrillar material and are a striking feature of myotonic dystrophy. However their significance is still unclear. Using immunocytochemistry we studied the expression of cytoskeletal proteins (desmin and vimentin), dystrophin, markers of myogenic differentiation (foetal myosin, neural cell adhesion molecule, bcl-2, insulin-like growth factor-I, fibroblast growth factor, retinoblastoma protein and myoD1), cell cycle regulators (Cdk2, p16, p27 and p57) and muscle proteases (ubiquitin, micro and m calpain and cathepsin D) in muscle biopsies from four patients with myotonic dystrophy. Sarcoplasmic masses were strongly positive for desmin, neural cell adhesion molecule, bcl-2, insulin-like growth factor I, retinoblastoma protein and p57, weakly positive for dystrophin and p16 and negative for vimentin, fibroblast growth factor, myoD1, Cdk2 and p27. Immunoreactivity for foetal myosin was detected only in a few fibres (< 1%). Our data suggest that the late myogenic differentiation programme is activated in sarcoplasmic masses although these areas do not reach complete maturation.

Here we describe the imaging findings in a 73-year-old woman who had pain in the right inguinal region, followed by progressive weakness of muscles innervated by the right femoral and obturator nerves, diagnosed as nondiabetic lumbosacral radiculoplexus neuropathy. Magnetic resonance neurography showed thickening and increase in signal intensity of the right femoral and obturator nerves.

Mitochondrial myopathies are often associated with point mutations in mitochondrial DNA (mtDNA), and are usually maternally inherited. However, they may also present as an isolated myopathy, often with ptosis and ophthalmoparesis,1 or with isolated exercise intolerance.2 In eight patients with exercise intolerance described by us in 1999,2 there was no evidence of maternal inheritance, muscle histochemistry showed cytochrome c oxidase (COX) positive ragged red fibres, biochemistry showed complex III deficiency, and molecular genetic analysis revealed different mutations in the mitochondrial cytochrome b gene (CYB) . Several other patients with lifelong exercise intolerance harboured mutations in other mtDNA protein coding genes.3 Characteristically, these mutations are not maternally inherited and are abundant (more than 90%) in skeletal muscle, where they coexist with smaller amounts of wild type mtDNA genomes. As a rule, the mutations are not present in other tissues and, surprisingly, are not found in cultured myoblasts, indicating that they are somatic mutations of skeletal muscle. However, the mechanism by which these mutations accumulate in muscle remains unknown. As the clinical presentation of all patients (lifelong progression of clinical symptoms), suggested that the molecular defect may accumulate over time, we looked for duplications in the D-loop as putative sources of replication advantage or disadvantage for mutant mtDNAs. Here, we report our findings in 10 patients harbouring different mtDNA mutations restricted to skeletal muscle; 5 patients with point mutations and 5 with single deletions. In all five patients with point mutations, we identified a 652 bp duplication in the mtDNA control region, which altered the promoter and replication elements. The duplication was restricted to skeletal muscle mtDNA, and analysis of subcloned PCR fragments encompassing both the site of the point mutation and the region of the duplication suggested that the duplication segregates independently from the point mutation. Our …