Biomedical subjects

Elena Pegoraro

Publications and source records attributed to Elena Pegoraro.

6 recordsLinked to original sources

PubMed2003

X-inactivation pattern in multiple tissues from two Leber's hereditary optic neuropathy (LHON) patients.

The more frequent manifestation of ophthalmological abnormalities in males, relative to females, is an unexplained feature of Leber's hereditary optic neuropathy (LHON) that suggests an X-linked modifying gene acting in concert with the pathogenic LHON mitochondrial DNA (mtDNA) mutation. In addition, segregation analysis of the optic neuropathy in LHON pedigrees was compatible with the presence of a recessive-modifying gene on chromosome X. According to this two-locus model, females would be affected only if homozygous or if they were susceptible to skewed X-inactivation. Attempts both to localize the putative LHON-modifying gene by linkage analysis and to find an excess of skewed X-inactivation in affected females were unsuccessful, although the inactivation pattern was only studied in DNA isolated from blood cells. We had the opportunity to analyze a wide range of tissues at autopsy, including the optic nerves and the retina, from two LHON female patients. We found no evidence of skewed X-inactivation in the affected tissues, thus weakening further the hypothesized involvement of a specific X chromosome locus in the pathophysiological expression of LHON.

Adult↗

PubMed2003

Clinical and molecular study in congenital muscular dystrophy with partial laminin alpha 2 (LAMA2) deficiency.

Complete laminin alpha2 (LAMA2) deficiency causes approximately half of congenital muscular dystrophy (CMD) cases. Many loss-of-function mutations have been reported in these severe, neonatal-onset patients, but only single missense mutations have been found in milder CMD with partial laminin alpha2 deficiency. Here, we studied nine patients diagnosed with CMD who showed abnormal white-matter signal at brain MRI and partial deficiency of laminin alpha2 on immunofluorescence of muscle biopsy. We screened the entire 9.5 kb laminin alpha2 mRNA from patient muscle biopsy by direct capillary automated sequencing, single strand conformational polymorphism (SSCP), or denaturing high performance liquid chromatography (DHPLC) of overlapping RT-PCR products followed by direct sequencing of heteroduplexes. We identified laminin alpha2 sequence changes in six of nine CMD patients. Each of the gene changes identified, except one, was novel, including three missense changes and two splice-site mutations. The finding of partial laminin alpha2 deficiency by immunostaining is not specific for laminin alpha2 gene mutation carriers, with only two patients (22%) showing clear causative mutations, and an additional three patients (33%) showing possible mutations. The clinical presentation and disease progression was homogeneous in the laminin alpha2-mutation positive and negative CMD patients.

Clubfoot↗

PubMed2003

Novel spastin mutations and their expression analysis in two Italian families.

Mutations in spastin cause the most common form of pure autosomal dominant hereditary spastic paraparesis (SPG4). Here, we report two Italian families affected with SPG4-linked HSP harboring two novel spastin mutations. SSCP/sequencing analysis of the spastin gene showed a single base pair deletion causing a frame-shift in one family (1442delT) and a missense mutation (1726T>C) resulting in a leucine to proline amino-acid change (L534P) in the other family. Total RNA from the mutant and the wild-type spastin allele in muscle biopsies from patients from the two affected families was quantitated. RNA expression was almost absent from the spastin allele harboring the single base pair deletion, while it was nearly normal for the spastin allele harboring the missense mutation. These data suggest that varying spastin RNA levels are found in out-of-frame and missense spastin mutations and imply different mechanisms involved in the molecular pathology of SPG4 linked HSP.

Adenosine Triphosphatases↗

PubMed2002

Gene expression profiling in dysferlinopathies using a dedicated muscle microarray.

We have performed expression profiling to define the molecular changes in dysferlinopathy using a novel dedicated microarray platform made with 3'-end skeletal muscle cDNAs. Eight dysferlinopathy patients, defined by western blot, immunohistochemistry and mutation analysis, were investigated with this technology. In a first experiment RNAs from different limb-girdle muscular dystrophy type 2B patients were pooled and compared with normal muscle RNA to characterize the general transcription pattern of this muscular disorder. Then the expression profiles of patients with different clinical traits were independently obtained and hierarchical clustering was applied to discover patient-specific gene variations. MHC class I genes and genes involved in protein biosynthesis were up-regulated in relation to muscle histopathological features. Conversely, the expression of genes codifying the sarcomeric proteins titin, nebulin and telethonin was down-regulated. Neither calpain-3 nor caveolin, a sarcolemmal protein interacting with dysferlin, was consistently reduced. There was a major up-regulation of proteins interacting with calcium, namely S100 calcium-binding proteins and sarcolipin, a sarcoplasmic calcium regulator.

Adolescent↗

PubMed2002

Integrin alpha 7 beta 1 in muscular dystrophy/myopathy of unknown etiology.

To investigate the role of integrin alpha 7 in muscle pathology, we used a "candidate gene" approach in a large cohort of muscular dystrophy/myopathy patients. Antibodies against the intracellular domain of the integrin alpha 7A and alpha 7B were used to stain muscle biopsies from 210 patients with muscular dystrophy/myopathy of unknown etiology. Levels of alpha 7A and alpha 7B integrin were found to be decreased in 35 of 210 patients (approximately 17%). In six of these patients no integrin alpha 7B was detected. Screening for alpha 7B mutation in 30 of 35 patients detected only one integrin alpha 7 missense mutation (the mutation on the second allele was not found) in a patient presenting with a congenital muscular dystrophy-like phenotype. No integrin alpha 7 gene mutations were identified in all of the other patients showing integrin alpha 7 deficiency. In the process of mutation analysis, we identified a novel integrin alpha 7 isoform presenting 72-bp deletion. This isoform results from a partial deletion of exon 21 due to the use of a cryptic splice site generated by a G to A missense mutation at nucleotide position 2644 in integrin alpha 7 cDNA. This spliced isoform is present in about 12% of the chromosomes studied. We conclude that secondary integrin alpha 7 deficiency is rather common in muscular dystrophy/myopathy of unknown etiology, emphasizing the multiple mechanisms that may modulate integrin function and stability.

Alternative Splicing↗

PubMed2002

Novel CLCN1 mutations with unique clinical and electrophysiological consequences.

Myotonia is a condition characterized by impaired relaxation of muscle following sudden forceful contraction. We systematically screened all 23 exons of the CLCN1 gene in 88 unrelated patients with myotonia and identified mutations in 14 patients. Six novel mutations were discovered: five were missense (S132C, L283F, T310M, F428S and T550M) found in heterozygous patients, and one was a nonsense mutation (E193X) in a homozygous patient. While five patients had a clinical diagnosis of myotonia congenita, the patient with the F428S mutation exhibited symptoms characteristic of paramyotonia congenita--a condition usually thought to be caused by mutations in the sodium channel gene SCN4A. Nevertheless, no mutations in SCN4A were identified in this patient. The functional consequences of the novel CLCN1 sequence variants were explored by recording chloride currents from human embryonic kidney cells transiently expressing homo- or heterodimeric mutant channels. The five tested mutations caused distinct functional alterations of the homodimeric human muscle chloride ion channel hClC-1. S132C and T550M conferred novel hyperpolarization-induced gating steps, L283F and T310M caused a shift of the activation curve to more positive potentials and F428S reduced the expression level of hClC-1 channels. All showed a dominant-negative effect. For S132C, L283F, T310M and T550M, heterodimeric channels consisting of one wild-type (WT) and one mutant subunit exhibited a shifted activation curve at low intracellular [Cl(-)]. WT-F428S channels displayed properties similar to WT hClC-1, but expressed at significantly lower levels. The novel mutations exhibit a broad variety of functional defects that, by distinct mechanisms, cause a significant reduction of the resting chloride conductance in muscle of heterozygous patients. Our results provide novel insights into functional alterations and clinical symptoms caused by mutations in CLCN1.

Adult↗