Glycogen storage disease type III: A novel Agl knockout mouse model

AbstractGlycogen storage disease type III is an autosomal recessive disease characterized by a deficiency in the glycogen debranching enzyme, encoded by AGL. Essential features of this disease are hepatomegaly, hypoglycemia, hyperlipidemia, and growth retardation. Progressive skeletal myopathy, neuropathy, and/or cardiomyopathy become prominent in adults. Currently, there is no available cure. We generated an Agl knockout mouse model by deletion of the carboxy terminus of the protein, including the carboxy end of the glucosidase domain and the glycogen-binding domain. Agl knockout mice presented serious hepatomegaly, but we did not observe signs of cirrhosis or adenomas. In affected tissues, glycogen storage was higher than in wild-type mice, even in the central nervous system which has never been tested in GSDIII patients. The biochemical findings were in accordance with histological data, which clearly documented tissue impairment due to glycogen accumulation. Indeed, electron microscopy revealed the disruption of contractile units due to glycogen infiltrations. Furthermore, adult Agl knockout animals appeared less prompt to move, and they exhibited kyphosis. Three-mo-old Agl knockout mice could not run, and adult mice showed exercise intolerance. In addition, older affected animals exhibited an accelerated respiratory rate even at basal conditions. This observation was correlated with severe glycogen accumulation in the diaphragm. Diffuse glycogen deposition was observed in the tongues of affected mice. Our results demonstrate that this Agl knockout mouse is a reliable model for human glycogenosis type III, as it recapitulates the essential phenotypic features of the disease

Cosegregation of novel mitochondrial 16S rRNA gene mutations with the age-associated T414G variant in human cybrids

Ever increasing evidence has been provided on the accumulation of mutations in the mitochondrial DNA (mtDNA) during the aging process. However, the lack of direct functional consequences of the mutant mtDNA load on the mitochondria-dependent cell metabolism has raised many questions on the physiological importance of the age-related mtDNA variations. In the present work, we have analyzed the bioenergetic properties associated with the age-related T414G mutation of the mtDNA control region in transmitochondrial cybrids. The results show that the T414G mutation does not cause per se any detectable bioenergetic change. Moreover, three mtDNA mutations clustered in the 16S ribosomal RNA gene cosegregated together with the T414G in the same cybrid cell line. Two of them, namely T1843C and A1940G, are novel and associate with a negative bioenergetic phenotype. The results are discussed in the more general context of the complex heterogeneity and the dramatic instability of the mitochondrial genome during cell culture of transmitochondrial cybrids

Clinical and molecular features of an infant patient affected by Leigh Disease associated to m.14459G > A mitochondrial DNA mutation: a case report

<p>Abstract</p> <p>Background</p> <p>Leigh Syndrome (LS) is a severe neurodegenerative disorder characterized by bilateral symmetrical necrotic lesions in the basal ganglia and brainstem. Onset is in early infancy and prognosis is poor. Causative mutations have been disclosed in mitochondrial DNA and nuclear genes affecting respiratory chain subunits and assembly factors.</p> <p>Case presentation</p> <p>Here we report the clinical and molecular features of a 15-month-old female LS patient. Direct sequencing of her muscle-derived mtDNA revealed the presence of two apparently homoplasmic variants: the novel m.14792C > G and the already known m.14459G > A resulting in p.His16Asp change in cytochrome b (MT-CYB) and p.Ala72Val substitution in ND6 subunit, respectively. The m.14459G > A was heteroplasmic in the mother's blood-derived DNA.</p> <p>Conclusions</p> <p>The m.14459G > A might lead to LS, complicated LS or Leber Optic Hereditary Neuropathy. A comprehensive re-evaluation of previously described 14459G > A-mutated patients does not explain this large clinical heterogeneity.</p

Clinical and molecular characterization of a cohort of patients with novel nucleotide alterations of the Dystrophin gene detected by direct sequencing

<p>Abstract</p> <p>Background</p> <p>Duchenne and Becker Muscular dystrophies (DMD/BMD) are allelic disorders caused by mutations in the dystrophin gene, which encodes a sarcolemmal protein responsible for muscle integrity. Deletions and duplications account for approximately 75% of mutations in DMD and 85% in BMD. The implementation of techniques allowing complete gene sequencing has focused attention on small point mutations and other mechanisms underlying complex rearrangements.</p> <p>Methods</p> <p>We selected 47 patients (41 families; 35 DMD, 6 BMD) without deletions and duplications in <it>DMD </it>gene (excluded by multiplex ligation-dependent probe amplification and multiplex polymerase chain reaction analysis). This cohort was investigated by systematic direct sequence analysis to study sequence variation. We focused our attention on rare mutational events which were further studied through transcript analysis.</p> <p>Results</p> <p>We identified 40 different nucleotide alterations in DMD gene and their clinical correlates; altogether, 16 mutations were novel. DMD probands carried 9 microinsertions/microdeletions, 19 nonsense mutations, and 7 splice-site mutations. BMD patients carried 2 nonsense mutations, 2 splice-site mutations, 1 missense substitution, and 1 single base insertion. The most frequent stop codon was TGA (n = 10 patients), followed by TAG (n = 7) and TAA (n = 4). We also analyzed the molecular mechanisms of five rare mutational events. They are two frame-shifting mutations in the <it>DMD </it>gene 3'end in BMD and three novel splicing defects: IVS42: c.6118-3C>A, which causes a leaky splice-site; c.9560A>G, which determines a cryptic splice-site activation and c.9564-426 T>G, which creates pseudoexon retention within IVS65.</p> <p>Conclusion</p> <p>The analysis of our patients' sample, carrying point mutations or complex rearrangements in <it>DMD </it>gene, contributes to the knowledge on phenotypic correlations in dystrophinopatic patients and can provide a better understanding of pre-mRNA maturation defects and dystrophin functional domains. These data can have a prognostic relevance and can be useful in directing new therapeutic approaches, which rely on a precise definition of the genetic defects as well as their molecular consequences.</p

Spontaneous hydromyelic cavity in two unrelated patients with late-onset pompe disease: is this a fortuitous association?

LetterSCOPUS: le.jinfo:eu-repo/semantics/publishe

Hydro(syringo)myelic Cavity in Two Unrelated Patients with Late Onset Pompe Disease: Is This a Fortuitous Association?

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Postural effects on lung and chest wall volumes in late onset type II glycogenosis patients.

Respiratory failure associated with diaphragmatic weakness is the first cause of death in late-onset type II glycogenosis (LO-GSDII). We aim to identify predictive factors of diaphragmatic weakness and investigate the pathophysiology of respiratory muscles impairment. Pulmonary function and chest wall volumes were measured in ten patients and eight controls (supine and seated). According to the change in forced vital capacity in supine (ΔFVC) we considered patients with (DW, ΔFVC>25%) and without (noDW, ΔFVC<25%) diaphragmatic weakness. Postural change made the supine abdominal contribution to tidal volume (%VAB) of DW to fall and the ribcage to increase and good correlation was found between %VAB and ΔFVC (R=0.776). Patients showed reduced chest wall and abdominal inspiratory capacity (ICCW and ICAB) (p<0.001) and low abdominal expiratory reserve volume (p<0.01). Passing to supine DW did not increase ICCW and ICAB. ΔFVC occurs in LO-GSDII due to weakened diaphragm and abdominal muscles while intercostals are preserved. %VAB represents a new reliable index to detect diaphragmatic weakness.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Adult-onset acid maltase deficiency: A rare clinical presentation

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