A third of LGMD2A biopsies have normal calpain 3 proteolytic activity as determined by an in vitro assay

Milić, Astrid; Danièle, Nathalie; Lochmüller, Hanns; Mora, Marina; Comi, Giacomo P.; Moggio, Maurizio; Noulet, Fanny; Walter, Maggie C.; Morandi, Lucia; Poupiot, Jérôme; Roudaut, Carinne; Bittner, Reginald E.; Bartoli, Marc; Richard, Isabelle

doi:10.1016/j.nmd.2006.11.001

Cited by 45 publications

(34 citation statements)

References 24 publications

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“…31,32 Furthermore, we feel that because of its high sensitivity (12% of false-negative results) and easy procedure, the functional test for calpain-3 autolytic activity is a valuable tool in the diagnostic algorithm of LGMD2A when protein quantity is normal.…”

Section: Discussionmentioning

confidence: 99%

How to tackle the diagnosis of limb-girdle muscular dystrophy 2A

et al. 2008

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Limb-girdle muscular dystrophy (LGMD) 2A (calpainopathy) is the most frequent form of LGMD in many European countries. The increasing demand for a molecular diagnosis makes the identification of strategies to improve gene mutation detection crucial. We conducted both a quantitative analysis of calpain-3 protein in 519 muscles from patients with unclassified LGMD, unclassified myopathy and hyperCKemia, and a functional assay of calpain-3 autolytic activity in 108 cases with LGMD and normal protein quantity. Subsequently, screening of CAPN3 gene mutations was performed using allele-specific tests and simplified SSCP analysis. We diagnosed a total of 94 LGMD2A patients, carrying 66 different mutations (six are newly identified). The probability of diagnosing calpainopathy was very high in patients showing either a quantitative (80%) or a functional calpain-3 protein defect (88%). Our data show a high predictive value for reduced-absent calpain-3 or lost autolytic activity. These biochemical assays are powerful tools for otherwise laborious genetic screening of cases with a high probability of being primary calpainopathy. Our multistep diagnostic approach is rational and highly effective. This strategy has improved the detection rate of the disease and our extension of screening to presymptomatic phenotypes (hyperCKemia) has allowed us to obtain early diagnoses, which has important consequences for patient care and genetic counseling.

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Section: Discussionmentioning

confidence: 99%

How to tackle the diagnosis of limb-girdle muscular dystrophy 2A

et al. 2008

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“…In this study, once divided in each separate diagnostic category, the relatively low number of patients within each disorder prevents a validation of this concept. It is also known that missense mutations are not functionally equivalent either in terms of enzymatic activity (for calpain-3) [Milic et al, 2007] or for assembling macromolecular complexes (for sarcoglycans), making prognosis a more difficult task. Therefore, larger databases, hopefully containing comparable observations, are needed to validate prognostic markers.…”

Section: Genotype Phenotype and Protein Expression Correlationsmentioning

confidence: 99%

Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients

et al. 2008

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Limb girdle muscular dystrophies (LGMD) are characterized by genetic and clinical heterogeneity: seven autosomal dominant and 12 autosomal recessive loci have so far been identified. Aims of this study were to evaluate the relative proportion of the different types of LGMD in 181 predominantly Italian LGMD patients (representing 155 independent families), to describe the clinical pattern of the different forms, and to identify possible correlations between genotype, phenotype, and protein expression levels, as prognostic factors. Based on protein data, the majority of probands (n=72) presented calpain-3 deficiency; other defects were as follows: dysferlin (n=31), sarcoglycans (n=32), alpha-dystroglycan (n=4), and caveolin-3 (n=2). Genetic analysis identified 111 different mutations, including 47 novel ones. LGMD relative frequency was as follows: LGMD1C (caveolin-3) 1.3%; LGMD2A (calpain-3) 28.4%; LGMD2B (dysferlin) 18.7%; LGMD2C (gamma-sarcoglycan) 4.5%; LGMD2D (alpha-sarcoglycan) 8.4%; LGMD2E (beta-sarcoglycan) 4.5%; LGMD2F (delta-sarcoglycan) 0.7%; LGMD2I (Fukutin-related protein) 6.4%; and undetermined 27.1%. Compared to Northern European populations, Italian patients are less likely to be affected with LGMD2I. The order of decreasing clinical severity was: sarcoglycanopathy, calpainopathy, dysferlinopathy, and caveolinopathy. LGMD2I patients showed both infantile noncongenital and mild late-onset presentations. Age at disease onset correlated with variability of genotype and protein levels in LGMD2B. Truncating mutations determined earlier onset than missense substitutions (20+/-5.1 years vs. 36.7+/-11.1 years; P=0.0037). Similarly, dysferlin absence was associated with an earlier onset when compared to partial deficiency (20.2+/-standard deviation [SD] 5.2 years vs. 28.4+/-SD 11.2 years; P=0.014).

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“…Milic at al. [15 ] developed an in-vitro calpain3 activity assay to test the protein autocatalytic and proteolytic properties and to identify protein activity abnormalities in patients with mutations in CAPN3 but normal quantitative calpain3 expression. A secondary deficiency of calpain3 has been described in several muscular dystrophies.…”

Section: Considering the Wide Clinical And Genetic Variability Ofmentioning

confidence: 99%