Impaired expression of insulin-like growth factor-1 system in skeletal muscle of amyotrophic lateral sclerosis patients.

INTRODUCTION: Adult muscle fibers are a source of growth factors, including insulin-like growth factor-1 (IGF-1). These factors influence neuronal survival, axonal growth, and maintenance of synaptic connections. METHODS: We investigated the components of the IGF system in skeletal muscle samples obtained from 17 sporadic amyotrophic lateral sclerosis patients (sALS) and 29 control subjects (17 with normal muscle and 12 with denervated muscle unrelated to ALS). RESULTS: The muscle expression of IGF-1 and IGF-binding proteins 3, 4, and 5 (IGF-BP3, -4, and -5, respectively), assessed by immunohistochemistry, was differently decreased in sALS compared with both control groups; conversely, IGF-1 receptor ß subunit (IGF-1Rß) was significantly increased. Western blot analysis confirmed the severe reduction of IGF-1, IGF-BP3, and -BP5 with the increment of IGF-1Rß in sALS. CONCLUSION: In this study we describe the abnormal expression of the IGF-1 system in skeletal muscle of sALS patients that could participate in motor neuron degeneration and should be taken into account when developing treatments with IGF-1.

An intragenic deletion/inversion event in the DMD gene determines a novel exon creation and results in a BMD phenotype.

Duchenne and Becker Muscular Dystrophy (DMD and BMD) are caused, in the majority of cases, by deletions in the dystrophin gene ( DMD). Here we describe the unprecedented case of a BMD patient carrying a large out-of-frame intragenic deletion, together with an inversion in the DMD gene, resulting in the inclusion of a novel exon in the transcript. Multiplex PCR amplification revealed the presence of a 48-52 exon deletion, but transcript analysis identified two unexpected products, neither of them including exon 53. The shorter mRNA derived from the juxtaposition of exons 47-54 (in-frame), while the longer one resulted from the inclusion of a novel 73-bp exon between exons 47 and 54. Sequence analysis revealed that the inserted sequence derived from an inverted portion of intron 53; its inclusion is predicted to determine protein truncation. The presence of a genomic inversion involving exon 53 and flanking regions was confirmed, and inversion/deletion breakpoints were sequenced. The inverted 73-bp sequence displays splicing signals at both ends and thus it is probably recognized as a novel exon when the partially inverted hnRNA is processed. These findings highlight the importance of mRNA analysis on patients that, based on routine DNA screenings, do not follow the reading-frame rule. This is the first reported patient carrying both an intragenic deletion and inversion in the DMD locus. This case might provide further insight into both the mechanisms that determine genomic rearrangements in the DMD locus and the molecular signals that drive exon inclusion.

Novel missense mutation and large deletion of GNE gene in autosomal-recessive inclusion-body myopathy.

The UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene is the causative gene for autosomal-recessive hereditary inclusion-body myopathy (h-IBM). Two sisters affected with autosomal-recessive h-IBM were shown to be compound heterozygous for two novel GNE mutations: a large deletion involving exons 1-9, and a R162C amino acid change in the epimerase domain. This is the first deletion event observed in a GNE allele and expands the molecular pathogenesis of autosomal-recessive h-IBM.

Severe chronic sensory-motor polyneuropathy: coexistence of 3 unrelated etiologies in a type 1 diabetic patient. A case report and review of the literature.

We present the case of a 58-year-old man, who has suffered from type 1 diabetes mellitus since he was young. He had monoclonal IgM kappa gammopathy of undetermined significance and high anti-MAG antibody titer. He developed a polyneuropathic picture with the clinical and laboratory features of chronic inflammatory demyelinating polyneuropathy within the span of approximately 2 years. He benefited from IV administration of high doses of immunoglobulins. Investigation of all parameters, but particularly of the clinical phenotype, can lead to a better definition of the polyneuropathic picture, especially for therapeutic and prognostic purposes.