Carlo P. Trevisan

Different mutations in the LMNA gene cause autosomal dominant and autosomal recessive Emery-Dreifuss muscular dystrophy.

Emery-Dreifuss muscular dystrophy (EMD) is a condition characterized by the clinical triad of early-onset contractures, progressive weakness in humeroperoneal muscles, and cardiomyopathy with conduction block. The disease was described for the first time as an X-linked muscular dystrophy, but autosomal dominant and autosomal recessive forms were reported. The genes for X-linked EMD and autosomal dominant EMD (AD-EMD) were identified. We report here that heterozygote mutations in LMNA, the gene for AD-EMD, may cause diverse phenotypes ranging from typical EMD to no phenotypic effect. Our results show that LMNA mutations are also responsible for the recessive form of the disease. Our results give further support to the notion that different genetic forms of EMD have a common pathophysiological background. The distribution of the mutations in AD-EMD patients (in the tail and in the 2A rod domain) suggests that unique interactions between lamin A/C and other nuclear components exist that have an important role in cardiac and skeletal muscle function.

Congenital muscular dystrophies with defective glycosylation of dystroglycan A population study

Background: Congenital muscular dystrophies (CMD) with reduced glycosylation of alpha-dystroglycan (α-DG) are a heterogeneous group of conditions associated with mutations in six genes encoding proven or putative glycosyltransferases. Objectives: The aim of the study was to establish the prevalence of mutations in the six genes in the Italian population and the spectrum of clinical and brain MRI findings. Methods: As part of a multicentric study involving all the tertiary neuromuscular centers in Italy, FKRP, POMT1, POMT2, POMGnT1, fukutin, and LARGE were screened in 81 patients with CMD and α-DG reduction on muscle biopsy (n = 76) or with a phenotype suggestive of α-dystroglycanopathy but in whom a muscle biopsy was not available for α-DG immunostaining (n = 5). Results: Homozygous and compound heterozygous mutations were detected in a total of 43/81 patients (53%), and included seven novel variants. Mutations in POMT1 were the most prevalent in our cohort (21%), followed by POMT2 (11%), POMGnT1 (10%), and FKRP (9%). One patient carried two heterozygous mutations in fukutin and one case harbored a new homozygous variant in LARGE. No clear-cut genotype-phenotype correlation could be observed with each gene, resulting in a wide spectrum of clinical phenotypes. The more severe phenotypes, however, appeared to be consistently associated with mutations predicted to result in a severe disruption of the respective genes. Conclusions: Our data broaden the clinical spectrum associated with mutations in glycosyltransferases and provide data on their prevalence in the Italian population.

Liver transplantation for Wilson's disease: The burden of neurological and psychiatric disorders

A retrospective data analysis on liver transplantation for Wilsons disease (WD) was performed among Italian Liver Transplant Centers. Thirty‐seven cases were identified. The main indication for liver transplantation was chronic advanced liver disease in 78% of patients. Mixed hepatic and neuropsychiatric symptoms were recorded in 32.3%. Eight patients presented with fulminant liver failure; 44.8% were on medical treatment. Patient and graft survival at 3 months, 12 months, 3 years, 5 years, and 10 years after transplantation were, respectively, 91.8%, 89.1%, 82.9%, 75.6%, and 58.8%, and 85.3%, 83.0%, 77.1%, 70.3%, and 47.2%. Neurological symptoms significantly improved after orthotopic liver transplantation (OLT), but the survival of patients with mixed hepatic and neuropsychiatric involvement was significantly lower than in patients with liver disease alone (P = 0.04). WD characterized by hepatic involvement alone is a rare but good indication for liver transplantation when specific medical therapy fails. Patients with neuropsychiatric signs have a significantly shorter survival even though liver transplantation has a positive impact on neurological symptoms. In conclusion, a combination of hepatic and neuropsychiatric conditions deserves careful neurological evaluation, which should contraindicate OLT in case of severe neurological impairment. (Liver Transpl 2005;11:1056–1063.)

Laminin α2 muscular dystrophy: Genotype/phenotype studies of 22 patients

Objective: To determine the number of primary laminin α2 gene mutations and to conduct genotype/phenotype correlation in a cohort of lamininα2-deficient congenital muscular dystrophy patients. Background: Congenital muscular dystrophies (CMD) are a heterogenous group of muscle disorders characterized by early onset muscular dystrophy and a variable involvement of the CNS. Laminin α2 deficiency has been reported in about 40 to 50% of cases of the occidental, classic type of CMD.1,2 Laminin α2 is a muscle specific isoform of laminin localized to the basal lamina of muscle fibers, where it is thought to interact with myofiber membrane receptor, such as integrins, and possibly dystrophin-associated glycoproteins.3,4 Methods: Seventy-five CMD patients were tested for laminin α2 expression by immunofluorescence and immunoblot. The entire 10 kb laminin α2 coding sequence of 22 completely laminin α2-deficient patients was screened for causative mutations by reverse transcription (RT)-PCR/single strand conformational polymorphisms (SSCP) analysis and protein truncation test(PTT) analysis followed by automatic sequencing of patient cDNA. Clinical data from the laminin α2-deficient patients were collected. Results: Thirty laminin α2-negative patients were identified (40% of CMD patients tested) and 22 of them were screened for laminin α2 mutations. Clinical features of laminin α2-deficient patients were similar, with severe floppiness at birth, delay in achievement of motor milestones, and MRI findings of white matter changes with normal intelligence. Loss-of-function mutations were identified in 95% (21/22) of the patients studied. SSCP analysis detected laminin α2 gene mutations in about 50% of the mutant chromosomes; PTT successfully identified 75% of the mutations. A two base pair deletion mutation at position 2,096-2,097 bp was present in 23% of the patients analyzed. Conclusions: Our data suggest that the large majority of laminin α2-deficient patients show laminin α2 gene mutations.

Phenotypic clustering of lamin A/C mutations in neuromuscular patients

Background: Mutations in the LMNA gene, encoding human lamin A/C, have been associated with an increasing number of disorders often involving skeletal and cardiac muscle, but no clear genotype/phenotype correlation could be established to date. Methods: We analyzed the LMNA gene in a large cohort of patients mainly affected by neuromuscular or cardiac disease and clustered mutated patients in two groups to unravel possible correlations. Results: We identified 28 variants, 9 of which reported for the first time. The two groups of patients were characterized by clinical and genetic differences: 1) patients with childhood onset displayed skeletal muscle involvement with predominant scapuloperoneal and facial weakness associated with missense mutations; 2) patients with adult onset mainly showed cardiac disorders or myopathy with limb girdle distribution, often associated with frameshift mutations presumably leading to a truncated protein. Conclusions: Our findings, supported by meta-analysis of previous literature, suggest the presence of two different pathogenetic mechanisms: late onset phenotypes may arise through loss of function secondary to haploinsufficiency, while dominant negative or toxic gain of function mechanisms may explain the severity of early phenotypes. This model of patient stratification may help patient management and facilitate future studies aimed at deciphering lamin A/C pathogenesis.

Genetic epidemiology of congenital muscular dystrophy in a sample from north-east Italy

Congenital muscular dystrophy (CMD) is a heterogenous disease with autosomic recessive transmission. In an epidemiological study in four provinces of Veneto (region of 2586830 inhabitants in north-east Italy), the recorded incidence rate for the period 1979–1993 was 4.65 x 10−5; the prevalence rate in the year 1993 was 6.8 × 10−6. The incidence and the prevalence rates that we have obtained during the course of our investigation represent the first estimates for CMD in Europe and show that this myopathy is among the most frequent neuromuscular diseases with autosomic recessive transmission.

Loss of Calpain-3 Autocatalytic Activity in LGMD2A Patients with Normal Protein Expression

The diagnosis of limb girdle muscular dystrophy (LGMD) type 2A (due to mutations in the gene encoding for calpain-3) is currently based on protein analysis, but mutant patients with normal protein expression have also been identified. In this study we investigated 150 LGMD patients with normal calpain-3 protein expression, identified gene mutations by an allele-specific polymerase chain reaction test, and analyzed the mutant calpain-3 catalytic activity. Four different mutations were found in eight patients (5.5%): a frame-shifting deletion (550 A del) and three missense (R490Q, R489Q, R490W). Patients with normal calpain-3 protein expression on Western blot are a considerable proportion (20%) of our total LGMD2A population. While in control muscle the calpain-3 Ca(++)-dependent autocatalytic activity was evident within 5 minutes and was prevented by ethylene diaminetetraacetic acid, in all mutant patient samples the protein was not degraded, indicating that the normal autocatalytic function had been lost. By this new functional test, we show that conventional protein diagnosis fails to detect some mutant proteins, and prove the pathogenetic role of R490Q, R489Q, R490W missense mutations. We suggest that these mutations impair protein activity by affecting interdomain protein interaction, or reduce autocatalytic activity by lowering the Ca(++) sensitivity.

Carnitine palmityl transferase deficiency Myoglobinuria and respiratory failure

A 51-year-old man presented with acute respiratory failure and myoglobinuria precipitated by an infection. Carnitine palmityltransferase (CPT) deficiency was documented in muscle, leukocytes, and liver. “he enzyme defect in liver, previously suspected and now documented, explained the decreased production of ketone bodies during fasting observed in this patient as well as others with muscle CFT deficiency. Decreased utilization of long-chain fatty acids and decreased availability of ketone bodies can deprive the muscle of crucial sources of energy and, in certain conditions, may precipitate myoglobinuria.

Facioscapulohumeral muscular dystrophy: epidemiological and molecular study in a north-east Italian population sample

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disease associated with a partial deletion on chromosome 4q35. Few relevant investigations have been reported on its epidemiology and were essentially based on clinical diagnosis, having been performed before recognition of the molecular mutation. We report an epidemiological survey on FSHD patients, in which the diagnosis was obtained by combined clinical and molecular evaluation. The survey concerned the north‐east Italian province of Padova, an area of 871,190 inhabitants (1 January 2004). We identified 40 patients affected by FSHD based on clinical diagnosis. In 33 of them, the EcoRI fragment size in the 4q35 region ranged from 14 to 35 kb. Four other patients belonging to the same family harbored a 38‐kb fragment. In these four cases, the relationship between the borderline deletion with the mild FSHD phenotype was corroborated by additional haplotype reconstruction and segregation analysis. Interestingly, the same mild facial‐sparing clinical pattern was apparent only in one other patient with an EcoRI fragment of 32 kb, suggesting that this unusual FSHD phenotype may be due to very small 4q35 deletions. On the whole, estimating a prevalence rate of 44 × 10−6, our survey confirmed FSHD as one of the most frequent neuromuscular disorders in Western populations.

Diagnosis and management of Wilson's disease: results of a single center experience.

Aims To report on the diagnostic features, management, and clinical outcome after different treatments of Wilsons disease patients followed over a mean period of 15 years. Patients Thirty-five patients with Wilsons disease referred to the University of Padovas Department of Gastroenterology for diagnosis or treatment were observed for a mean 15 years. The diagnosis was based on clinical symptoms, laboratory tests (ceruloplasmin, urinary, and hepatic copper concentrations), and uptake of the radiostable isotope 65Cu into the plasma protein pool. Hepatic Cu content was measured by regular follow-up biopsies. Neurologic outcome after therapy was assessed using a newly developed scoring system. Results Twenty-three (65.7%) patients presented with liver disease; 12 (34.3%) had mixed neurologic and hepatic involvement. All patients had been initially treated with either penicillamine (23) or zinc sulfate (12). The neurologic symptoms became worse or remained stationary in 75% of those treated with penicillamine, whereas zinc treatment improved these symptoms in 90% of treated cases. Both treatments were effective in improving the hepatic symptoms. No differences in hepatic Cu content emerged between follow-up biopsies in either treatment group. Six patients (26%) had to abandon the penicillamine treatment due to side effects. In all, 4 patients underwent liver transplantation, which was successful in 3, with a mean survival after transplantation of 4.6 years; the fourth, who had a severe neurologic impairment, died of central pontine myelinolysis. Conclusions Penicillamine and zinc can effectively treat Wilsons disease, though the side effects of penicillamine may be severe enough to prompt its suspension. Liver transplantation remains the treatment of choice for end-stage liver disease.