We present here the clinical, molecular and biochemical findings from 238 limb-girdle muscular dystrophy type 2A (LGMD2A) patients, representing approximately 50% (238 out of 484) of the suspected calpainopathy cases referred for the molecular study of the calpain 3 (CAPN3) gene. The mean age at onset of LGMD2A patients was approximately 14 years, and the first symptoms occurred between 6 and 18 years of age in 71% of patients. The mean age at which the patients became wheelchair bound was 32.2 years, with 84% requiring the use of a wheelchair between the age of 21 and 40 years. There was no correlation between the age at onset and the time at which the patient became wheelchair bound, nor between the sex of the patient and the risk of becoming wheelchair bound. Of the cases where the CAPN3 gene was not affected, approximately 20% were diagnosed as LGMD2I muscular dystrophy, while facioscapulohumeral muscular dystrophy (FSHD) was uncommon in this sample. We identified 105 different mutations in the CAPN3 gene of which 50 have not been described previously. These were distributed throughout the coding region of the gene, although some exons remained free of mutations. The most frequent mutation was 2362AG-->TCATCT (exon 22), which was present in 30.7% of the chromosomes analysed (146 chromosomes). Other recurrent mutations described were N50S, 550DeltaA, G222R, IVS6-1G-->A, A483D, IVS17+1G-->T, 2069-2070DeltaAC, R748Q and R748X, each of which was found in >5 chromosomes. The type of mutation in the CAPN3 gene does not appear to be a risk factor for becoming dependent on a wheelchair at a determined age. However, in the cases with two null mutations, there were significantly fewer patients that were able to walk than in the group of patients with at least one missense mutation. Despite the fact that the results of phenotyping and western blot might be biased due to multiple referral centres, producing a diagnosis on the basis of the classical phenotype is neither sufficiently sensitive (86.7%) nor specific (69.3%), although western blot proved to be even less sensitive (52.5%) yet more specific (87.8%). In this case LGMD2I was a relevant cause of false-positive diagnoses. Considering both the clinical phenotype and the biochemical information together, the probability of correctly diagnosing a calpainopathy is very high (90.8%). However, if one of the analyses is lacking, the probability varies from 78.3 to 73.7% depending on the information available. When both tests are negative, the probability that the sample comes from a patient with LGMD2A was 12.2%.

Chemotherapy-induced peripheral neuropathy (CIN) is a common toxicity of anticancer treatment and its incidence is growing. It significantly affects quality of life and is a dose-limiting factor that interferes with treatment. Its diagnosis can be established in clinical terms but some complementary tests can help when the diagnosis is difficult. There is still no proven method to prevent it that has become a standard of care in spite of the huge amount of investigation carried out in recent years. There are promising strategies that could help reduce the burden of this complication. This review will suggest an approach to the diagnosis of these disorders and provide an update on new therapies.

Summary Lysosomal α-galactosidase A (α-Gal) is the enzyme deficient in Fabry disease (FD), an X-linked glycosphingolipidosis caused by pathogenic mutations affecting the GLA gene. The early-onset, multi-systemic FD classical phenotype is associated with absent or severe enzyme deficiency, as measured by in vitro assays, but patients with higher levels of residual α-Gal activity may have later-onset, more organ-restricted clinical presentations. A change in the codon 118 of the wild-type α-Gal sequence, replacing basic arginine by a potentially sulfhydryl-binding cysteine residue – GLA p.(Arg118Cys) –, has been recurrently described in large FD screening studies of high-risk patients. Although the Cys118 allele is associated with high residual α-Gal activity in vitro, it has been classified as a pathogenic mutation, mainly on the basis of theoretical arguments about the chemistry of the cysteine residue. However its pathogenicity has never been convincingly demonstrated by pathology criteria. We reviewed the clinical, biochemical and histopathology data obtained from 22 individuals of Portuguese and Spanish ancestry carrying the Cys118 allele, including 3 homozygous females. Cases were identified either on the differential diagnosis of possible FD manifestations and on case-finding studies (n=11; 4 males), or on unbiased cascade screening of probands’ close relatives (n=11; 3 males). Overall, those data strongly suggest that the GLA p.(Arg118Cys) variant does not segregate with FD clinical phenotypes in a Mendelian fashion, but might be a modulator of the multifactorial risk of cerebrovascular disease, since the allelic frequency in stroke patients was 0.0087 (p=0.0185 vs the general population). The Cys118 allelic frequency in healthy Portuguese adults (n=696) has been estimated as 0.001, therefore not qualifying for “rare” condition.

No abstract

We report a 29-year-old patient with McArdle's disease and myasthenia gravis. She had been debilitated with McArdle's disease since childhood (with marked rhabdomyolysis) and was obese. Myasthenia gravis was diagnosed at 24 years of age. After 3 months of aerobic exercise training, her exercise capacity increased significantly and she regained the ability to live independently. We conclude that even patients with profound neuromuscular diseases may benefit from carefully prescribed exercise training.

A significant percentage of patients did not require any additional drugs in the long term. This suggests that treatment effect or disease outcome may be stable over time, and treatment regimens should therefore be individualized to avoid overtreatment.

Clinical, electrophysiologic and molecular studies were performed on at-risk members of 14 families with hereditary neuropathy with liability to pressure palsies (HNPP), in order to detect asymptomatic carriers of the 17p11.2 deletion. Sporadic cases due to de novo deletion accounted for 21% of the investigated HNPP families. Approximately one half of deletion carriers were asymptomatic and did not display significant signs on clinical examination. The electrophysiologic hallmark in both symptomatic and asymptomatic deletion carriers was the presence of a nonuniform sensorimotor demyelinating polyneuropathy with conduction abnormalities preferentially located at common entrapment sites and distal nerve segments. A perfect correlation was found between the molecular and electrophysiologic analyses. A reliable screening method to detect clinically unaffected carriers of the deletion in families with HNPP was the evaluation of motor conduction in at least two nerves across usual entrapment sites, especially the ulnar nerve at the elbow, and evaluation of sensory conduction in the sural nerve. In sporadic cases due to a de novo deletion, electrophysiologic studies were suggestive but not sufficient for the diagnosis, and molecular analysis represented the most sensitive diagnostic tool.

Limb-girdle muscular dystrophy type 2A (LGMD2A) is an autosomal recessive disorder caused by mutations in the CAPN3 gene. Its definitive diagnosis is laborious, since the clinical phenotype is often similar to other types of muscular dystrophy and since the CAPN3 gene encompasses a large genomic region with more than 300 pathogenic mutations described to date. In fact, it is estimated that nearly 25% of the cases with a phenotype suggestive of LGMD2A do not have mutations in the CAPN3 gene and that, in up to 22% of the cases, only one mutation is identified. In the present work, we have characterised CAPN3 messenger RNA (mRNA) expression in peripheral blood, and we have performed a retrospective diagnostic study with 26 LGMD2A patients, sequencing a transcript of CAPN3 present in white blood cells (WBCs). The 25% of the mutations presented in this paper (7/28) act modifying pre-mRNA splicing of the CAPN3 transcript, including the first deep-intronic mutation described to date in the CAPN3 gene. Our results determine that the sequencing of CAPN3 transcripts present in WBCs could be applied as a new approach for LGMD2A diagnosis. This method improves and simplifies diagnosis, since it combines the advantages of mRNA analysis in a more accessible and rapidly regenerated tissue. However, the lack of exon 15 in the CAPN3 isoforms present in blood, and the presence of mRNA degradation make it necessary to combine mRNA and DNA analyses in some specific cases.