Search

Late-onset Pompe disease (LOPD) includes patients from 1 year of age to adulthood. The vast heterogeneity in clinical manifestations and disease progression is not fully explained; however, a short disease duration and a young age seem to be good predictors of a better response to treatment. For this purpose, we investigated and followed up a cohort of 13 juvenile patients with LOPD from the clinical and therapeutic point of view, mainly pointing out the transition from presymptomatic to symptomatic status. We retrospectively collected clinical, morphological, biochemical and molecular data from 13 juvenile LOPD patients. Motor and respiratory functional data, obtained during annual follow-up visits, were analyzed. The data included serial evaluations of the Medical Research Council (MRC) scale, the 6-Minute Walking Test (6MWT), the Gait, Stairs, Gower, and Chair (GSGC) score, and seated and supine Forced Vital Capacity (FVC). Muscle Magnetic Resonance Imaging (MRI) was also included, although it was not performed in all cases. Currently, patients mean age is 18 years. All patients but one were diagnosed because of an isolated hyperCKemia: the mean age at diagnosis was 6.8 years (range 1-18). The onset of symptoms occurred from 6 months to 12 years after the diagnosis. The mean clinical follow-up duration was 9 years (range 2-18). From the genetic point of view, the most shared mutation was c.32-13T>G, found in twelve patients as compound heterozygosis. Seven patients underwent muscle biopsy, which showed vacuolar myopathy with glycogen accumulation in four of them with unspecific changes in the other three cases. Five patients developed proximal muscle weakness during the follow-up with a mild waddling gait and a positive Gowers manoeuver. Muscle MRI revealed mild hypotrophy of the thighs at the development of symptoms in four out of five cases. Four patients started alglucosidase alfa, and one avalglucosidase alfa. These five patients on Enzyme Replacement Therapy (ERT) showed motor and respiratory stability in the following years. Timely identification of emerging clinical manifestations in presymptomatic LOPD patients, as a result of careful follow-up, is essential to start prompt treatment to modify the disease natural course., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: OM and AT received honoraria from Sanofi Genzyme., (Copyright © 2025 The Author(s). Published by Elsevier B.V. All rights reserved.)

Muscle Glycogenosis type 0 (GSD0B) is an extremely rare disorder first recognized in 2007 in three siblings with childhood onset and severe cardiomyopathy. Since then, a few cases with severe cardiac involvement and premature death have been reported. We describe two unrelated cases presenting with an adult-onset myopathy with no heart involvement. Clinical features were quite similar in both patients, mainly characterized by early fatigability, myalgia and muscle weakness. Muscle biopsy revealed marked glycogen depletion in nearly all myofibers. Biochemical assay demonstrated a marked reduction of Glycogen Synthase (GS) activity. Sequence analysis of GYS1 revealed two new variants: a homozygous G to C substitution in the splice donor consensus site (c.678+1G>C) in patient1 and a homozygous missense variant c.630G>C in exon 3 (p. Asp145His) in patient 2. This study describes a new phenotype of muscle GSD0B presenting with adult onset, proximal myopathy, no cardiac abnormalities and a quite benign disease course. This report highlights the importance of a systematic diagnostic approach that includes muscle morphology and enzymatic assay to facilitate the identification of adult patients with GSD0B., Competing Interests: Declaration of competing interest All other authors report no disclosures., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Mutations in the GAA gene may cause a late onset Pompe disease presenting with proximal weakness without the characteristic muscle pathology, and therefore a test for GAA activity is the first tier analysis in all undiagnosed patients with hyperCKemia and/or limb-girdle muscular weakness. By using MotorPlex, a targeted gene panel for next generation sequencing, we analyzed GAA and other muscle disease-genes in a large cohort of undiagnosed patients with suspected inherited skeletal muscle disorders (n = 504). In this cohort, 275 patients presented with limb-girdle phenotype and/or an isolated hyperCKemia. Mutational analysis identified GAA mutations in ten patients. Further seven affected relatives were identified by segregation studies. All the patients carried the common GAA mutation c.-32-13T >G and a second, previously reported mutation. In the subcohort of 275 patients with proximal muscle weakness and/or hyperCKemia, we identified late-onset Pompe disease in 10 patients. The clinical overlap between Pompe disease and LGMDs or other skeletal muscle disorders suggests that GAA and the genes causing a metabolic myopathy should be analyzed in all the gene panels used for testing neuromuscular patients. However, enzymatic tests are essential for the interpretation and validation of genetic results., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Danon disease, an X-linked multisystemic disorder, is due to deficiency of Lysosome-Associated Membrane Protein 2 (LAMP2). It is usually characterized by hypertrophic cardiomyopathy, mental retardation and skeletal myopathy, sometimes also with atypical features. A 20-year-old man with cognitive impairment was admitted to the Emergency Room because of a sudden chest pain. ECG showed Wolff-Parkinson-White syndrome; echocardiography revealed hypertrophic cardiomyopathy, and, shortly after, he experienced a cardiac arrest followed by an occipital ischemic stroke. On neurological examination, he complained of visual loss, and diffuse muscle wasting and weakness were also unexpectedly noted. Electromyography evidenced a myopathic pattern and a peripheral neuropathy. A muscle biopsy disclosed vacuolar myopathy with glycogen storage; immunohistochemical studies demonstrated a LAMP-2 deficiency. LAMP2 molecular analysis identified a "de novo" mutation (p. Q353X). This patient with a neglected Danon disease, experienced an unusual complication as a stroke due to cerebral hypoperfusion after cardiac arrest caused by WPW syndrome., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Involvement of the peripheral nervous system in mitochondrial disorders has been previously reported. However, the prevalence of peripheral neuropathy in mitochondrial disorders is still unclear. Based on the large database of the "Nation-wide Italian Collaborative Network of Mitochondrial Diseases", we reviewed the clinical data of 1200 patients, with special regard to peripheral neuropathy (mean age at onset 24.3 ± 20.1 years; age at last evaluation 39.8 ± 22.3 years; females 52.7%; childhood onset [before age 16 years] 43.1%). Peripheral neuropathy was present in 143/1156 patients (12.4%), being one of the ten most common signs and symptoms. POLG mutations cause a potentially painful, axonal/mixed, mainly sensory polyneuropathy; TYMP mutations lead to a demyelinating sensory-motor polyneuropathy; SURF1 mutations are associated with a demyelinating/mixed sensory-motor polyneuropathy. The only mtDNA mutation consistently associated with peripheral neuropathy (although less severely than in the above-considered nuclear genes) was the m.8993T > G (or the rarer T > C) changes, which lead to an axonal, mainly sensory polyneuropathy. In conclusion, peripheral neuropathy is one of the most common features of a mitochondrial disorder, and may negatively impact on the quality of life of these patients. Furthermore, the presence or absence of peripheral neuropathy, as well as its specific forms and the association with neuropathic pain (indicative of a POLG-associated disease) can guide the molecular analysis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Mutations in the MTM1 gene cause X-linked myotubular myopathy (XLMTM), characterized by neonatal hypotonia and respiratory failure, and are responsible for a premature mortality in affected males. Female carriers are usually asymptomatic but they may present with muscular weakness because of a hypothesized skewed pattern of X-chromosome inactivation. By combining next generation sequencing (NGS) and CGH array approaches, we have investigated the role of MTM1 variants in a large cohort of undiagnosed patients with a wide spectrum of myopathies. Seven novel XLMTM patients have been identified, including two girls with an unremarkable family history for myotubular myopathy. Moreover, we have detected and finely mapped a large deletion causing a myotubular myopathy with abnormal genital development. Our data confirm that the severe neonatal onset of the disease in male infants is sufficient to address the direct molecular testing toward the MTM1 gene and, above all, suggest that the number of undiagnosed symptomatic female carriers is probably underestimated., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Respiratory insufficiency commonly develops in patients with Late Onset Pompe Disease (LOPD). It is conceivable that a timely starting of enzyme replacement therapy could avoid this life-threatening complication. Respiratory function in LOPD is commonly evaluated with standard pulmonary tests which do not extensively provide an accurate definition of the muscular pathophysiology. In eleven patients with LOPD and five healthy subjects, we compared pulmonary function results with MRI data, based on scans of the right lung acquired on maximum expiration and inspiration. We observed that variations in the cranio-caudal lung height and of lung areas in inspiration and expiration (lung delta) as well as the area of diaphragmatic movement strongly correlated with pulmonary function results. Moreover, MRI data confirmed that development of respiratory insufficiency in LOPD is mainly due to the diaphragmatic weakness with sparing of the antero-posterior chest expansion related to the activity of the intercostal muscles. These results suggest that respiratory muscle MRI is a quick, useful and reproducible tool for patient management as well as a reliable outcome measure for future LOPD therapeutic trials., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Homozygosity for the common Caucasian splice site mutation c.-32-13T>G in intron 1 of the GAA gene is rather rare in Pompe patients. We report on the clinical, biochemical, morphological, muscle imaging, and genetic findings of six adult Pompe patients from five unrelated families with the c.-32-13T>G GAA gene mutation in homozygous state. All patients had decreased GAA activity and elevated creatine kinase levels. Five patients, aged between 43 and 61 years (median 53 years), initially presented with myalgia, hyperCKaemia, and/or exercise induced fatigue at an age of onset (12-55 years). All but one had proximal lower limb weakness combined with axial weakness and moderate respiratory insufficiency; the sixth patient presented with hyperCKaemia only. Muscle biopsies showed PAS-positive vacuolar myopathy with lysosomal changes and reduced GAA activity. Muscle MRI of lower limb muscles revealed a moderate adipose substitution of the gluteal muscles, biceps femoris and slight fatty infiltration of all thigh muscles. One MRI of the respiratory muscles revealed a diaphragmatic atrophy with unilateral diaphragm elevation. So, the common Caucasian, so called mild, splice site mutation c.-32-13T>G in intron 1 of the GAA gene in a homozygote status reflects the full adult Pompe disease phenotype severity spectrum., (Copyright © 2015 Elsevier B.V. All rights reserved.)

We studied 786 undiagnosed patients with LGMD or nonspecific myopathic features to investigate the role of ANO5 mutations in limb-girdle muscular dystrophies (LGMDs) and in nonspecific myopathies using the next generation sequencing (NGS) approach. In 160 LGMD patients, we first sequenced hotspot exons 5 and 20 and then sequenced the remaining part of the coding region. Another 626 patients, recruited using broader inclusion criteria, were directly analyzed by targeted NGS. By combining NGS and Sanger sequencing, we identified 33/786 (4%) patients carrying putative pathogenic changes in both alleles and 23 ANO5 heterozygotes (3%). The phenotypic spectrum is broader than expected, from hyperCKemia to myopathies, with lack of genotype/phenotype correlations. In particular, this is currently the largest screening of the ANO5 gene. The large number of heterozygotes for damaging mutations suggests that anoctaminopathies should be frequent and often nonpenetrant. We propose the multiple genetic testing by targeted NGS as a first step to analyze patients with nonspecific myopathic presentations. This represents a straightforward approach to overcome the difficulties of clinical heterogeneity of ANO5 patients, and to test, at the same time, many other genes involved in neuromuscular disorders., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

In patients with late-onset Pompe disease, we explored the role of the Cardiopulmonary Exercise Test (CPET) and the Six-Minute Walking Test (6MWT) in the assessment of exercise capacity and in the evaluation of the effects of enzyme replacement therapy (ERT). Eight patients affected by late-onset Pompe disease, followed up at the Centre for Neuromuscular Diseases and treated with ERT, underwent a baseline evaluation with a spirometry, a CPET and a 6MWT. Four of them were restudied after 36 months of treatment. Three patients showed a reduction in exercise capacity as evaluated by peak oxygen uptake (VO2) measured at the CPET and Distance Walked (DW) measured at the 6MWT (median % predicted: 67.1 [range 54.3-99.6] and 67.3 [56.6-82.6], respectively). Cardiac and respiratory limitations revealed by the CPET were correlated to peak VO2, but not to the DW. Nevertheless, percent of predicted values of peak VO2 and DW were strongly correlated (rho = 0.85, p = 0.006), and close to identity. In the longitudinal evaluation forced vital capacity decreased, while peak VO2 and DW showed a trend to a parallel improvement. We concluded that although only the CPET revealed causes of exercise limitation, which partially differed among patients, CPET and 6MWT showed a similar overall degree of exercise impairment. That held true in the longitudinal assessment during ERT, where both tests demonstrated similar small improvements, occurring despite deterioration in forced vital capacity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A 24-year-old woman complained of a 4-year history of muscle cramps, stiffness of the right lower limb and walking difficulties. After clinical and laboratory investigations, a diagnosis of multiple sclerosis was made. However, her family history revealed that her father and an older sister had lifelong symptoms of impaired muscle relaxation following contraction, improving with physical exercise. Molecular genetic studies in both sisters confirmed the diagnosis of myotonia congenita, due to a c.568GG>TC (Gly190Ser) pathogenic mutation in CLCN1 gene. Occurrence of two different neurological conditions in the same patient, both manifesting with stiffness, is quite unusual and suggests the opportunity of an accurate differential diagnosis., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Muscle phosphofructokinase (PFKM) deficiency, a rare disorder of glycogen metabolism also known as glycogen storage disease type VII (GSDVII), is characterized by exercise intolerance, myalgias, cramps and episodic myoglobinuria associated with compensated hemolytic anaemia and hyperuricemia. We studied five patients with PFKM deficiency coming from different Italian regions. All probands showed exercise intolerance, hyperCKemia, cramps and myoglobinuria. One patient had a mild hypertrophic cardiomyopathy. Biochemical studies revealed residual PFK activity ranging from 1 to 5%. Molecular genetic analysis identified four novel mutations in the PFKM gene. In our series of patients, clinical and laboratory features were similar in all but one patient, who had an unusual phenotype characterized by 25 ears disease history, high CK levels, hypertrophic cardiomyopathy with paroxysmal atrial fibrillation without fixed muscle weakness., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Carnitine palmitoyltransferase 2 (CPT2) deficiency is the most common defect of mitochondrial fatty acid oxidation; three different clinical phenotypes have been described but the adult form, involving exclusively the skeletal muscle, is the most frequent. We describe herein 3 families where 4 individuals manifested with the adult form of CPT2 deficiency. CPT2 gene molecular analysis identified the homozygous R631C mutation, so far only reported in severe infantile cases. Our data evidenced that R631C mutation is not exclusively detected in the infantile form but it may be present in a wider spectrum of CPT2 phenotypes. These findings indirectly suggest that other modulators may influence clinical severity of CPT2 deficiency.

At age of 57 years, a man experienced an episode of rhabdomyolysis. On that occasion muscle biopsy was not performed, however monoclonal gammopathy of undetermined significance (MGUS) was diagnosed. Further he developed a moderate proximal muscle weakness with CK level persistently elevated (1000-1200U/l). When he came to our observation, at age 67, a muscle biopsy revealed an amyloid myopathy and multiple myeloma was at the same time disclosed. Terminal complement complex C5b9 (membrane attack complex) deposits were found in the vessel walls and muscle fibers surface depicted by amyloid. Our case suggests to keep in mind the possibility that amyloid myopathy may begin as an isolate episode of rhabdomyolysis. The detection of complement complex C5b9 suggests that complement cascade is implicated in the muscular damage of amyloid myopathy.

Primary lysosome-associated membrane protein-2 (LAMP-2) deficiency is an X-linked disease, characterized by the clinical triad of cardiomyopathy, vacuolar myopathy and mental retardation, previously known as Danon disease. Mutations of lamp-2 gene have been reported so far in about 20 patients, one of whom was Italian. We describe a new Italian case with persistent hyperCKemia, exercise intolerance and hypertrophic cardiomyopathy but with no muscle weakness or mental impairment. Muscle biopsy revealed a vacuolar myopathy with mild glycogen storage, and immunohistochemical studies detected LAMP-2 deficiency. A new nucleotide substitution (T961C) on exon 8 of lamp-2 gene was identified as responsible for the protein deficiency. This is the first missense mutation so far described. LAMP-2 deficiency should be considered as a cause of recurrent hyperCKemia and hypertrophic cardiomyopathy.

Using direct sequencing and restriction fragment length polymorphism analysis, we identified two novel mutations in two unrelated Yemenite-Jewish families with typical symptoms of McArdle's disease. In one family, both father and daughter were affected, an example of pseudo-dominant transmission. The daughter was a compound heterozygote for a new nonsense mutation (R207X) and a new missense mutation (R602Q) while her father was homozygous for the R207X mutation. The mother carried only the R602Q mutation and was an asymptomatic heterozygote. In the second family, the only affected member was homozygous for the R207X mutation. This first molecular genetic study of McArdle's disease in Yemenite-Jewish patients expands the already remarkable genetic heterogeneity of McArdle's disease and suggests the existence of ethnic or private mutations within this group.