[Show abstract][Hide abstract] ABSTRACT: Centronuclear myopathies (CNMs) are a group of clinically and genetically heterogeneous
muscle disorders. To date, mutation in 7 different genes has been reported to cause CNMs but 30 % of cases still remain genetically undefined. Genetic investigations are often expensive and time consuming. Clinical and morphological clues are needed to facilitate genetic tests and to choose the best approach for genetic screening. We aimed to describe genotype–phenotype correlation in an Italian cohort of patients affected by CNMs, to define the relative frequencies of its defined genetic forms and to draw a diagnostic algorithm to address genetic investigations. We recruited patients with CNMs from all the Italian tertiary neuromuscular centers following clinical and histological criteria. All selected patients were screened for the four ‘canonical’ genes related to CNMs: MTM1, DNM2, RYR1 and BIN1. Pathogenetic mutations were found in 38 of the 54 screened patients (70 %), mostly in patients with congenital onset (25 of 30 patients, 83 %): 15 in MTM1, 6 in DNM2, 3 in RYR1 and one in TTN. Among the 13 patients with a childhood–adolescence onset, mutations were found in 6 patients (46 %), all in DNM2. In the group of the 11 patients with adult onset, mutations were identified in 7 patients (63 %), again in DNM2, confirming that variants in this gene are relatively more common in late-onset phenotypes. The present study provides the relative molecular frequency of centronuclear myopathy and of its genetically defined forms in Italy and also proposes a diagnostic algorithm to be used in clinical practice to address genetic investigations.
No preview · Article · May 2015 · Journal of Neurology
[Show abstract][Hide abstract] ABSTRACT: Leukoencephalopathy with thalamus and brainstem involvement and high lactate (LTBL) is a novel mitochondrial disease caused by mutations in EARS2, which encodes the mitochondrial glutamyl-tRNA synthetase (mtGluRS). A distinctive brain MRI pattern is the hallmark of the disease.
A 6-year-old boy presented at 3 months with feeding difficulties and muscle hypotonia. Brain MRI, at 8 months, showed hyperintensity of the deep cerebral and cerebellar white matter, thalamus, basal ganglia, brainstem, and thin corpus callosum. From the second year of life onward, the child reported global clinical improvement, parallel to partial resolution of brain MRI pattern. However, the last neuroimaging assessment revealed novel lesions within the left caudate and pallidum nuclei. DNA genomic sequencing analysis identified a novel EARS2 mutation.
This case expands the clinical and neuroradiological phenotype of LTBL presenting intermediate clinical manifestations between the severe and milder forms of the disease and previously unreported brain MRI features.
[Show abstract][Hide abstract] ABSTRACT: ATP synthase or complex V (cV) of the oxidative phosphorylation system is responsible for the production of ATP, dissipating the electrochemical gradient generated by the mitochondrial respiratory chain. In addition to maternally transmitted cV dysfunction caused by mutations in mtDNA genes (MT-ATP6 or MT-ATP8), encoding cV subunits, recessive mutations in the nuclear TMEM70 are the most frequent cause of ATP synthase deficiency.
We report on a cohort of ten Italian patients presenting with neonatal lactic acidosis, respiratory distress, hypotonia, cardiomyopathy and psychomotor delay and harbouring mutations in TMEM70, including the common splice mutation and four novel variants. TMEM70 protein was virtually absent in all tested TMEM70 patients’ specimens.
The exact function of TMEM70 is not known, but it is considered to impact on cV assembly since TMEM70 mutations have been associated with isolated cV activity reduction. We detected a clear cV biochemical defect in TMEM70 patients’ fibroblasts, whereas the assay was not reliable in frozen muscle. Nevertheless, the evaluation of the amount of holocomplexes in patients with TMEM70 mutations showed a nearly absent cV in muscles and a strong decrease of cV with accumulation of sub-assembly species in fibroblasts. In our cohort we found not only cV deficiencies but also impairment of other OXPHOS complexes. By ultrastructural analysis of muscle tissue from one patient with isolated cV deficiency, we found a severely impaired mitochondrial morphology with loss of the cristae. These findings indicate that cV impairment could indirectly alter other respiratory chain complex activities by disrupting the mitochondrial cristae structure.
[Show abstract][Hide abstract] ABSTRACT: Chanarin-Dorfman syndrome (CDS) is a rare nonlysosomal neutral lipid storage disorder characterized by congenital ichthyosis, lipid vacuoles in leukocytes (Jordan's anomaly), and hepatomegaly. The authors herein report an 18-month-old boy with ichthyosis and hepatomegaly diagnosed with CDS and confirmed to have a novel c.506-3C>G mutation in the ABHD5/CGI-58 gene. Our case also illustrates that retinoids such as acitretin could be useful in the treatment of skin manifestations in CDS even in the presence of liver derangement.
Full-text · Article · Jun 2013 · Pediatric Dermatology
[Show abstract][Hide abstract] ABSTRACT: Pontocerebellar hypoplasia (PCH) type 1 is characterized by the co-occurrence of spinal anterior horn involvement and hypoplasia of the cerebellum and pons. EXOSC3 has been recently defined as a major cause of PCH type 1. Three different phenotypes showing variable severity have been reported. We identified a homozygous mutation [c.395A > C/p.D132A] in EXOSC3 in four patients with muscle hypotonia, developmental delay, spinal anterior horn involvement, and prolonged survival, consistent with the "mild PCH1 phenotype". Interestingly, isolated cerebellar hypoplasia limited to the hemispheres or involving both hemispheres and vermis was the main neuroradiologic finding, whereas the pontine volume was in the normal range for age. These findings strongly suggest that analysis of the EXOSC3 gene should be recommended also in patients with spinal anterior horn involvement and isolated cerebellar hypoplasia.
No preview · Article · Apr 2013 · Journal of Neurology
[Show abstract][Hide abstract] ABSTRACT: Pontocerebellar hypoplasias represent a group of neurodegenerative autosomal recessive disorders characterized by hypoplasia/atrophy of the cerebellum, hypoplastic ventral pons, and microcephaly and associated with various clinical features. Pontocerebellar hypolasia type 2 is the most common form, and different mutations in genes encoding subunits of the transfer ribonucleic acid (RNA)-splicing endonuclease (TSEN) complex were identified in patients. The authors report clinical, imaging, and molecular studies in 2 unrelated patients with different clinical pictures of the pontocerebellar hypoplasia type 2 spectrum and novel mutations in TSEN54, aiming to further define the clinical spectrum of the disease and possible indicators of more favorable progression. They identified a novel missense mutation c.355T>G/p.Y119D in compound heterozygosity with the "common" c.919G>T/p.A307S (patient 1) and a novel homozygous c.7ins6(CCGGAG)/p.E2-P3insPE variant (patient 2). An expanded array of mutations might contribute in defining possible differences in severity and phenotype-genotype correlations.
No preview · Article · Jan 2013 · Journal of child neurology
[Show abstract][Hide abstract] ABSTRACT: We report a 14-year-old-boy with markedly elevated serum creatine kinase (CK) levels, in whom massive triglyceride storage was found in peripheral blood leukocytes and in muscle biopsy. Sequencing PNPLA2, the gene encoding the adipose triglyceride lipase (ATGL) and responsible for the neutral lipid storage disease with myopathy (NLSDM), we identified two heterozygous mutations, including a previously reported nonsense and a novel missense mutation in the patatin domain of the gene. Lipid storage myopathy can be clinically silent in childhood and presenting only with hyperCKemia.
Full-text · Article · Nov 2012 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene have been associated with early onset encephalopathy with signs of oxidative phosphorylation defects classified as pontocerebellar hypoplasia 6. We describe clinical, neuroimaging and molecular features on five patients from three unrelated families who displayed mutations in RARS2. All patients rapidly developed a neonatal or early-infantile epileptic encephalopathy with intractable seizures. The long-term follow-up revealed a virtual absence of psychomotor development, progressive microcephaly, and feeding difficulties. Mitochondrial respiratory chain enzymes in muscle and fibroblasts were normal in two. Blood and CSF lactate was abnormally elevated in all five patients at early stages while appearing only occasionally abnormal with the progression of the disease. Cerebellar vermis hypoplasia with normal aspect of the cerebral and cerebellar hemispheres appeared within the first months of life at brain MRI. In three patients follow-up neuroimaging revealed a progressive pontocerebellar and cerebral cortical atrophy. Molecular investigations of RARS2 disclosed the c.25A>G/p.I9V and the c.1586+3A>T in family A, the c.734G>A/p.R245Q and the c.1406G>A/p.R469H in family B, and the c.721T>A/p.W241R and c.35A>G/p.Q12R in family C. Functional complementation studies in Saccharomyces cerevisiae showed that mutation MSR1-R531H (equivalent to human p.R469H) abolished respiration whereas the MSR1-R306Q strain (corresponding to p.R245Q) displayed a reduced growth on non-fermentable YPG medium. Although mutations functionally disrupted yeast we found a relatively well preserved arginine aminoacylation of mitochondrial tRNA. Clinical and neuroimaging findings are important clues to raise suspicion and to reach diagnostic accuracy for RARS2 mutations considering that biochemical abnormalities may be absent in muscle biopsy.
Full-text · Article · May 2012 · Journal of Inherited Metabolic Disease
[Show abstract][Hide abstract] ABSTRACT: 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.
No preview · Article · Nov 2011 · Neuromuscular Disorders
[Show abstract][Hide abstract] ABSTRACT: Fanin M, Anichini A, Cassandrini D, Fiorillo C, Scapolan S, Minetti C, Cassanello M, Donati MA, Siciliano G, D’Amico A, Lilliu F, Bruno C, Angelini C. Allelic and phenotypic heterogeneity in 49 Italian patients with the muscle form of CPT-II deficiency.As genotype–phenotype correlations require the study of large patient populations, we investigated 49 Italian patients (33 unreported) with the muscle form of carnitine-palmitoyl-transferase-II (CPT-II) deficiency and CPT2 gene mutations. CPT enzyme activity below 25% of controls would lead to the development of muscle symptoms, and CPT activity below 15% would cause a relatively severe phenotype of the muscle form. Of the 15 different mutations found, 6 are novel (40%). A functional significance of mutations could be derived only for the two homozygous missense mutations found: both the p.S113L and the p.R631C (recurring in four unrelated patients from a genetic isolate) alleles caused a severe CPT enzyme defect (15% and 7%, respectively) and a relatively severe clinical phenotype of the muscle form. We identified three genotypes (homozygous p.R631C, homozygous p.S113L, and heterozygous null mutations) usually associated with a relatively severe and often life-threatening condition, which should be considered both in the clinical management of newly diagnosed patients (to prevent symptoms) and in their possible inclusion in therapeutic trials. We confirmed the existence of symptomatic heterozygous patient(s), through a family study, providing an important issue when offering genetic counseling and suggesting the crucial role of polymorphisms or environmental factors in determining the phenotype.
Full-text · Article · Oct 2011 · Clinical Genetics
[Show abstract][Hide abstract] ABSTRACT: Fanin M, Anichini A, Cassandrini D, Fiorillo C, Scapolan S, Minetti C, Cassanello M, Donati MA, Siciliano G, D’Amico A, Lilliu F, Bruno C, Angelini C. Allelic and phenotypic heterogeneity in 49 Italian patients with the muscle form of CPT-II deficiency.
As genotype–phenotype correlations require the study of large patient populations, we investigated 49 Italian patients (33 unreported) with the muscle form of carnitine-palmitoyl-transferase-II (CPT-II) deficiency and CPT2 gene mutations. CPT enzyme activity below 25% of controls would lead to the development of muscle symptoms, and CPT activity below 15% would cause a relatively severe phenotype of the muscle form. Of the 15 different mutations found, 6 are novel (40%). A functional significance of mutations could be derived only for the two homozygous missense mutations found: both the p.S113L and the p.R631C (recurring in four unrelated patients from a genetic isolate) alleles caused a severe CPT enzyme defect (15% and 7%, respectively) and a relatively severe clinical phenotype of the muscle form. We identified three genotypes (homozygous p.R631C, homozygous p.S113L, and heterozygous null mutations) usually associated with a relatively severe and often life-threatening condition, which should be considered both in the clinical management of newly diagnosed patients (to prevent symptoms) and in their possible inclusion in therapeutic trials. We confirmed the existence of symptomatic heterozygous patient(s), through a family study, providing an important issue when offering genetic counseling and suggesting the crucial role of polymorphisms or environmental factors in determining the phenotype.
[Show abstract][Hide abstract] ABSTRACT: Cerebellar and brainstem hypoplasia may occur in different conditions, including those disorders designated as pontocerebellar hypoplasia (PCH). In particular, when PCH is combined with severe supratentorial white matter involvement and cerebral atrophy, mutations in the mitochondrial arginyl-tRNA synthethase (RARS2) gene causing PCH6 are possible. We describe a patient with a lethal mitochondrial encephalomyopathy due to a mtDNA deletion and no alterations in RARS2, whose magnetic resonance (MR) findings mimicked PCH6. A thorough diagnostic work-up for mitochondrial disorders should be carried out when facing with a PCH-like and severe white matter and basal ganglia involvement on brain MR imaging in children, even if clinical and laboratory mitochondrial "stigmata" are scant or nonspecific.
No preview · Article · Aug 2011 · Journal of Inherited Metabolic Disease
[Show abstract][Hide abstract] ABSTRACT: Pyridoxine-dependent seizures (PDS) is a rare disorder characterized by seizures resistant to anticonvulsants but controlled by daily pharmacologic doses of pyridoxine. Mutations in the antiquitin (ALDH7A1) gene have recently reported to cause PDS in most of patients. We report the long-term follow-up in two PDS siblings carrying a novel ALDH7A1 mutation.
No preview · Article · Jul 2011 · European journal of paediatric neurology: EJPN: official journal of the European Paediatric Neurology Society
[Show abstract][Hide abstract] ABSTRACT: We report an 11-year-old boy with exercise-related myopathy, and a novel mutation m.5669G>A in the mitochondrial tRNA Asparagine gene (mt-tRNA(Asn), MTTN). Muscle biopsy studies showed COX-negative, SDH-positive fibers at histochemistry and biochemical defects of oxidative metabolism. The m.5669G>A mutation was present only in patient's muscle resulting in the first muscle-specific MTTN mutation. Mt-tRNA(Asn) steady-state levels and in silico predictions supported the pathogenicity of this mutation. A mitochondrial myopathy should be considered in the differential diagnosis of exercise intolerance in children.
No preview · Article · Jun 2011 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: The adult or 'muscular' form of carnitine-palmitoyl-transferase II (CPT II) deficiency presents with recurrent rhabdomyolytic episodes and myoglobinuria, usually triggered by prolonged exercise. The aim of this study was to investigate a large series of patients in order to provide genotype-phenotype correlations.
Our muscle tissue bank was surveyed for patients showing attacks of rhabdomyolysis with myoglobinuria. After exclusion of cases affected with toxic myoglobinuria, McArdle's disease and Becker muscular dystrophy, over 100 patients were selected for isotope-exchange radioenzymatic assay of CPT enzyme activity in muscle, and 25 cases resulted to be defective. Acylcarnitine profile was performed in five patients using tandem mass spectrometry. Mutations in the CPT2 gene were identified using DNA sequencing.
Although the clinical features were rather homogeneous, some patients presented life-threatening events (acute renal failure) and muscle weakness, and low levels of residual CPT activity. The typical acylcarnitine profile found in mutant patients confirmed its value as a screening method for further diagnostic investigations. We found a high frequency of the common p.Ser113Leu mutation, the recurrence of the rare p.Arg631Cys mutation in a genetic isolate in Southern Italy, and identified four novel mutations. In some affected patients only one mutant allele was found, suggesting either incomplete mutation detection or the possibility they are symptomatic carriers.
Null mutations and homozygous mutations were frequently associated with a more severe phenotype and biochemical defect. The identification of symptomatic obligate heterozygous carriers might suggest that additional epigenetic or environmental factors may contribute to determine the phenotype.
Full-text · Article · Jan 2011 · Neurological Research
[Show abstract][Hide abstract] ABSTRACT: Hereditary inclusion body myopathy (IBM2) was mainly reported in Middle Eastern Jewish patients. Distal myopathy with rimmed vacuoles has been described as a worldwide distributed distal myopathy. Both diseases are caused by mutations of the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene. Herein we report two patients: an Egyptian Muslim patient with the "common" Middle Eastern mutation (M712T), rarely described in non-Jewish patients; and an Italian patient carrying a novel GNE mutation (L179F) in the epimerase domain. Our patients share common clinical and histopathological features, with some interesting aspects. The first patient presented a clinical deterioration during her first pregnancy confirming that an increased requirement of sialic acid during pregnancy may trigger a clinical worsening. The second patient showed a slowly progressive deterioration, different from other patients carrying mutations in the epimerase domain, who had a severe and rapid progression.
Full-text · Article · Mar 2010 · Neurological Sciences