Screening for later-onset Pompe's disease in patients with paucisymptomatic hyperCKemia.

BACKGROUND: Pompe's disease is an inherited metabolic myopathy caused by acid α-glucosidase deficiency. Early diagnosis optimizes the treatment effectiveness. METHODS: One-hundred-thirty-seven consecutive patients with unexplained hyperCKemia underwent the assessment of acid α-glucosidase activity on dried blood spot. Second tier confirmatory testing in positive patients included the assessment of α-glucosidase activity on lymphocytes or muscle tissue and molecular analysis. RESULTS: Three patients were diagnosed with later-onset Pompe's disease, revealing 2.2% prevalence in asymptomatic hyperCKemia. Moreover, three patients positive to the screening revealed abnormal biochemical second tier testing, but were heterozygous for the common c.-32-13T>G mutation at molecular level. CONCLUSIONS: The selective screening for later-onset Pompe's disease in asymptomatic hyperCKemia allowed the identification of affected patients in a pre-clinical stage. Additionally, the identification of carriers with biochemical alterations related to Pompe's disease extends the spectrum of its manifestations to heterozygous subjects.

Differential diagnosis of vacuolar muscle biopsies: use of p62, LC3 and LAMP2 immunohistochemistry.

Intrafibral vacuoles are the morphological hallmark in a wide variety of human skeletal muscle disorders with different etiology. In most cases, differential diagnosis is feasible with a routine histochemical work up of muscle biopsy. Ultrastructural analysis is an important confirmatory tool, but it is not widely available. Immunohistochemical stainings for p62, LAMP2 and LC3 are commonly available as tissutal marker for autophagy. We compared the immunohistochemical patterns for autophagic markers p62, LC3 and LAMP2 with routine histochemical markers in 39 biopsies from patients with definite diagnoses of glycogen storage disease type 2 (LOPD or Pompe disease, PD), sporadic inclusion body myositis (sIBM), oculo-pharyngeal muscular dystrophy (OPMD) and necrotizing myopathy (NM). Moreover, we also analyzed muscles of 10 normal controls. In PD group, LC3 and LAMP2 showed an higher percentage of positive fibers, whereas p62 was limited to a minority of fibers, thus paralleling the results of histochemical stainings; in NM group, LAMP2 and LC-3 were diffusely and unspecifically expressed in necrotic fibers, with p62 significantly expressed only in two cases. OPMD biopsies did not reveal any significant positivity. The most interesting results were observed in sIBM group, where p62 was expressed in all cases, even in fibers without other markers positivity. There results, although limited to a small number of cases, suggest that the contemporary use of p62, LAMP2 and LC-3 staining may have an adjunctive role in characterizing muscle fiber vacuoles, revealing autophagic pathway activation and providing further clues for the understanding of pathogenetic mechanisms.s.

Deregulation of the p14ARF/Mdm2/p53 pathway and G1/S transition in two glioblastoma sets.

Sixty-one glioblastomas have been studied, subdivided into the categories of classic glioblastomas (GBM) and glioblastomas with astrocytic (GBA) and oligodendroglial (GBO) differentiated areas. On surgical samples, TP53, Mdm2, CDKN2A/p16-p14 alterations were studied by molecular biology techniques and by immunohistochemistry. It has been found that Mdm2 amplification was more frequent in GBM than in GBA and GBO, that p14ARF was inactivated in a high percentage of cases in the three tumor categories. Both these and other alterations did not reach a statistical significance, with the exception of CDKN2A/p16 homozygous deletion which showed the highest frequency in GBO. The latter finding could be in line with the observation that CDKN2A/p16 inactivation is a step in the molecular pathway to tumor progression in oligodendrogliomas. TP53 mutations and Mdm2 amplifications were mutually exclusive, whereas TP53 mutations and CDKN2A/p14 inactivation coexisted in 5 cases. The alterations of the p53/Mdm2/p14ARF pathway occurred in 73% of cases and in 80% of cases if CDKN2A homozygous deletions were associated. All glioblastomas with gemistocytic areas showed p14ARF inactivation. Immunohistochemistry showed higher percentages of positivity in comparison with molecular genetics, but with similar variations.