Ataxia and congenital muscular dystrophy: the follow-up of a new specific phenotype.

Cerebellar hypoplasia may, at neuroimaging studies, be found in association with congenital muscular dystrophy (CMD), although it is an extremely rare occurrence. We here report on three CMD patients who underwent a longitudinal evaluation of clinical and neuroimaging features for a mean period of 18 years. Case 1, a 22-year-old woman, and cases 2 and 3, brothers aged 26 and 20 years, respectively, had presented a mild to moderate muscular weakness and increased serum creatine kinase (CK) levels since birth. All cases were diagnosed in the first years of life, with identification of evident dystrophic changes at muscle biopsy and moderate to severe cerebellar hypoplasia at brain computed tomography (CT) scan. Subsequently, all the patients underwent a second muscle biopsy, with immunostaining and immunoblot analysis, which showed normal values for merosin, dystrophin and dystrophin-related proteins. During the longitudinal study, the patients underwent repeated neurological and psychiatric examinations, serum CK controls, intellectual ability assessments and neuroimaging evaluations (CT and/or magnetic resonance imaging (MRI)). In all cases, these investigations indicated a mild to moderate deficit in the proximal muscles and a clear-cut cerebellar syndrome which, it was assumed, had been present since the first years. The patients also presented some intellectual difficulties, with an IQ of 0.69 in case 1, 0.83 in case 2 and 0.61 in case 3. The clinical course of all the patients was static, and all symptoms of the combined muscle and brain involvement persisted. Nor were any changes in the cerebellar hypoplasia observed at repeat MRIs. Findings obtained by us on the longitudinal study and a review of the literature indicate that cerebellar hypoplasia and merosin-positive CMD constitute a particular clinical phenotype, mainly characterized by an ataxic syndrome associated with a non-severe muscular involvement and a possible mild intellectual impairment.

Riboflavin therapy. Biochemical heterogeneity in two adult lipid storage myopathies.

Two unrelated adult males, aged 36 (patient 1) and 25 (patient 2) years, presented with subacute carnitine-deficient lipid storage myopathy that was totally and partly responsive to riboflavin supplementation in the two patients, respectively. Plasma acyl-carnitine and urinary organic acid profiles indicated multiple acyl coenzyme A dehydrogenase deficiency, which was mild in patient 1 and severe in patient 2. The activities of short-chain and medium-chain acyl coenzyme A dehydrogenases in mitochondrial fractions were decreased, especially in patient 2. This was in agreement with Western blotting results. Flavin-dependent complexes I and II were studied by immunoblotting and densitometric quantification of two-dimensional electrophoresis with comparable results. Complex I was present in normal amounts in both patients, whereas complex II was decreased only in the pretherapy muscle of patient 2. Flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) concentrations in muscle and isolated mitochondria, and the activity of mitochondrial FAD pyrophosphatase, showed that patient 1 had low levels of FAD (46%) and FMN (49%) in mitochondria, with a significant increase (P < 0.01) in mitochondrial FAD pyrophosphatase (273%) compared with controls. Patient 2 had similar low levels of FAD and FMN in both total muscle (FAD and FMN 22% of controls) and mitochondria (FAD 26%; FMN 16%) and normal activity of mitochondrial FAD pyrophosphatase. All of these biochemical parameters were either totally or partly corrected after riboflavin therapy.

Heart involvement in muscular dystrophies due to sarcoglycan gene mutations.

Mutations in the sarcoglycan genes cause autosomal-recessive muscular dystrophies. Because sarcoglycan genes and their protein products are highly expressed both in skeletal and cardiac muscle, patients with these mutations might be expected to be at risk to develop dilated cardiomyopathy. We therefore studied 13 patients with alpha-, beta-, gamma-sarcoglycan gene mutations by thorough cardiological assessment. Electrocardiographic or echocardiographic abnormalities were observed in about 30% of cases showing a severe course of muscular dystrophy. No correlation was found between the presence of cardiac abnormalities and the type of mutation or sarcoglycan gene involved. The cardiac involvement was never severe, but it may be detected in early stages of the muscle disease. The absence of overt cardiac dysfunction may be due to lower sarcoglycan protein expression in cardiac than skeletal muscle or to less sarcolemmal instability at the myocardial level, possibly related to the different distribution of forces generated by contraction of the myocardium with respect to proximal limb-girdle muscles.

The clinical spectrum of sarcoglycanopathies.

A group of 204 muscular dystrophy patients were screened for immunohistochemical and biochemical alpha-sarcoglycan defect and their DNA was analyzed for pathogenetic mutation in the four sarcoglycan genes. We identified 21 patients with alpha-, beta-, or gamma-sarcoglycan gene mutations. Patients with alpha-sarcoglycan gene mutations were clinically heterogeneous and showed either a rapid progressive or a late-onset slow course. In the slowly evolving group, a residual alpha-sarcoglycan protein was present, and its level correlated with a milder disease course and significant later inability to stand up from the floor (p < 0.00005). Most patients with beta- and gamma-sarcoglycan gene mutations presented a severe clinical course. There is a considerably different pattern of muscle involvement and disease course in these disorders, compared with dystrophinopathies.

Homozygous alpha-sarcoglycan mutation in two siblings: one asymptomatic and one steroid-responsive mild limb-girdle muscular dystrophy patient.

We describe a couple of siblings who have a homozygous mutation in the alpha-sarcoglycan gene and present a striking clinical difference in their phenotype; the brother is asymptomatic, and the sister is affected with mild limb-girdle muscular dystrophy. Drug therapy with a new steroid (deflazacort) was done over 6 months in the mild limb-girdle patient, and we observed objective benefit in muscle strength and in functional tests. Side effects were minimal. Immunohistochemistry for alpha-sarcoglycan showed reduced intensity of reaction in the limb-girdle dystrophy patient and was similar to normal in the asymptomatic case. A reduced amount of residual alpha-sarcoglycan protein level was found in their muscle biopsies. Unknown epigenetic or environmental factors may have an important role in determining protein and clinical phenotype expression. This is the first report of a patient with homozygous sarcoglycan gene mutation without overt muscle weakness in his adulthood. The spectrum of clinical phenotypes in sarcoglycanopathies is therefore wider than previously thought.

Genetic epidemiology of muscular dystrophies resulting from sarcoglycan gene mutations.

BACKGROUND: The autosomal recessive limb-girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous muscle diseases characterised by progressive proximal limb muscle weakness. Six different loci have been mapped and pathogenetic mutations in the genes encoding the sarcoglycan complex components (alpha-, beta-, gamma-, and delta-sarcoglycan) have been documented. LGMD patients affected with primary "sarcoglycanopathies" are classified as LGMD2D, 2E, 2C, and 2F, respectively. METHODS: A geographical area in north east Italy (2,319,147 inhabitants) was selected for a genetic epidemiological study on primary sarcoglycanopathies. Within the period 1982 to 1996, all patients living in this region and diagnosed with muscular dystrophy were seen at our centre. Immunohistochemical and immunoblot screening for alpha-sarcoglycan protein deficiency was performed on all muscle biopsies from patients with a progressive muscular dystrophy of unknown aetiology and normal dystrophin. Sarcoglycan mutation analyses were conducted on all patient muscle biopsies shown to have complete or partial absence of alpha-sarcoglycan immunostaining or a decreased quantity of alpha-sarcoglycan protein on immunoblotting. RESULTS: Two hundred and four patient muscle biopsies were screened for alpha-sarcoglycan protein deficiency and 18 biopsies showed a deficiency. Pathogenetic mutations involving one gene for sarcoglycan complex components were identified in 13 patients: alpha-sarcoglycan in seven, beta-sarcoglycan in two, gamma-sarcoglycan in four, and none in the delta-sarcoglycan gene. The overall prevalence of primary sarcoglycanopathies, as of 31 December 1996, was estimated to be 5.6 x 10(-6) inhabitants. CONCLUSION: The prevalence rate estimated in this study is the first to be obtained after biochemical and molecular genetic screening for sarcoglycan defects.

Myocardial involvement is very frequent among patients affected with subclinical Becker's muscular dystrophy.

BACKGROUND: Several cases of Becker's muscular dystrophy (BMD) have been reported, which showed mild or subclinical skeletal muscle involvement with an overt dilated cardiomyopathy. Here, for the first time, a group of 28 patients with BMD who had a subclinical or benign myopathy have been studied through a thorough cardiological assessment. METHODS AND RESULTS: Each patient underwent ECG and echocardiographic examinations. Molecular analyses of the dystrophin gene and protein were performed. An unexpectedly high incidence of myocardial involvement was observed among patients affected with subclinical (72%) or benign (60%) BMD. The cardiac involvement appears to develop early from the right ventricle. Both the increase in left ventricular end-diastolic volume and the reduction in the ejection fraction appeared to be age related. Severe left ventricular dilation with reduced ejection fraction, which could be complicated by life-threatening arrhythmias, may occur. Contrary to previous reports, which indicated the involvement of 5'-end mutations in cardiomyopathies as a result of dystrophin gene alterations, this study shows that despite the apparent concentration of deletions in two regions (5'-end and exons 47 through 49), no general conclusions can be drawn regarding the involvement of specific gene mutations in the development of cardiomyopathy. CONCLUSIONS: Cardiomyopathy is the main clinical feature and complication in patients affected by subclinical or mild BMD. The cardiac manifestation is characterized by early right ventricular involvement and is later associated with left ventricular impairment. In mild BMD, myocardial damage may develop because the patients, who are unaware of a possible cardiac involvement, are still able to perform strenuous muscle exercise and, through pressure or volume overload, may induce mechanical stress, which is harmful for dystrophin-deficient myocardial cells.

Prognostic factors in mild dystrophinopathies.

One hundred twenty five patients from 105 families were considered, showing in-frame intragenic deletion or duplication of the dystrophin gene and/or abnormal dystrophin on muscle biopsy. According to clinical status of patients, the affection was classified as subclinical, benign, moderate or severe. Significant decrease of dystrophin abundance was observed with increasing clinical severity (p < 0.05). Detailed clinical data were available in 68 patients in whom a long-term follow-up (6-39 years) was obtained. Functional performance at different ages and disease endpoints were recorded in order to analyze the rate of disease progression. We identified three different disease courses: stable, slow and rapid progression. We observed a significantly lower level of dystrophin and immunohistochemical score (p < 0.05 vs. the other courses) in patients with rapid course. Deletion or duplication in the 5' end of the gene was associated with poor prognosis. Prognosis was substantially better, showing a stable course, in patients with large deletions or duplications in the proximal rod region. These subjects often suffered from a cramps/myalgia syndrome or experienced rhabdomyolisis. Cardiac involvement was detected in 65% of cases. A significant increase of right ventricular volume was seen in all clinical groups (p < 0.05). A left ventricular dilation was observed in 25% and a decreased ejection fraction in 29% of our patients. The reduction of ejection fraction and the increase of left ventricular volume were age-related. Since sudden death may occur as a consequence of cardiomyopathy, severe left ventricular dysfunction in dystrophinopathic patients is another important adverse prognostic factor, although not always directly correlated with skeletal muscle impairment.

Duchenne phenotype with in-frame deletion removing major portion of dystrophin rod: threshold effect for deletion size?

In a 9-year-old boy with Duchenne muscular dystrophy we found a large in-frame deletion, spanning exons 10 to 53 of the dystrophin gene. The deletion removed almost all of the central rod domain of dystrophin. Using carboxyterminal dystrophin antibodies the immunohistochemical reaction was normal in all muscle fibers. In immunoblot studies we found dystrophin of abnormal size (160 kDa) and normal amount (about 100%). The immunochemical features and the reading frame deduced from DNA analysis are usually associated with Becker muscular dystrophy, but the clinical characteristics were those of the severe Duchenne phenotype. All the cases of in-frame dystrophin deletions reported so far, which involved more than 36 exons, invariably resulted in a severe phenotype. Therefore, a threshold effect for dystrophin length may be reasonably suspected. Very short dystrophin molecules might induce a severe disarray of the dystrophin network.

Clinical-molecular correlation in 104 mild X-linked muscular dystrophy patients: characterization of sub-clinical phenotypes.

A multidisciplinary study was conducted in order to assess dystrophin expression in a large series of mild X-linked muscular dystrophy patients, with well-defined clinical phenotype. Patients (104) were divided in 4 clinical groups, according to clinical severity: asymptomatic (sub-clinical), benign, moderate and severe, Cardiopathy was also assessed, and dilated cardiomyopathy was found in 47% of sub-clinical and benign cases. Myoglobinuria, cramps and myalgia were also associated with a sub-clinical or benign clinical status. Dystrophin immunohistochemical pattern of labelling and dystrophin amount decreased gradually across clinical groups. Our study showed a significative correlation between: (1) dystrophin amount and immunohistochemical score (p < 0.05); (2) dystrophin amount and clinical score (p < 0.05). Therefore, the combined use of these different techniques for prognosis of mild X-linked muscular dystrophy patients is useful. Our study assesses the prevalence of the various disease courses in a large cohort of mild X-linked muscular dystrophy patients. From our series, up to 30% of patients may be either asymptomatic or have sub-clinical changes.

Prevalent cardiac involvement in dystrophin Becker type mutation.

Myocardial involvement is frequently present in Xp21-linked muscular dystrophy, due to a lack of dystrophin in cardiac fibres. We describe a 41-yr-old man affected by dilated cardiomyopathy with sporadic episodes of myoglobinuria induced by effort and increased levels of serum creatine kinase. Very mild signs of skeletal myopathy were clinically evident. His mother was affected by an indefinite cardiopathy and suddenly died when she was 36 yr old. Muscle biopsy of the patient showed a dystrophic process. Dystrophin analysis together with a genetic DMD locus study led us to diagnose Becker type muscular dystrophy, with truncated dystrophin and a gene deletion extending from exon 45 to 48. Prevalent cardiac involvement in a Becker type mutation of the dystrophin gene further confirms clinical variability of dystrophinopathies.

Reverse transcription-polymerase chain reaction phenotyping of metalloproteinases and inhibitors involved in tumor matrix invasion.

The matrix metalloproteinase enzymes have been implicated in tumor invasion and metastasis by a series of correlative immunohistochemical studies. In addition, direct evidence for the role of these enzymes in this pathologic process comes from studies using specific metalloproteinase inhibitors to block tumor invasion and metastasis formation, both in vitro and in vivo. Synthetic oligonucleotide primers for four metalloproteinases (MMP-1, MMP-2, MMP-9, MMP-10) and their tissue inhibitors (TIMP-1, TIMP-2) were selected, synthesized, and optimized in the reverse transcriptase-polymerase chain reaction (RT-PCR) to study the qualitative profile of these enzymes and inhibitors in cultured human tumor cells and tumor tissues. These primers are specific and generate unique amplification products for each appropriate enzyme and inhibitor. Slight enhancement in the amplification of cDNA products was achieved by adding dimethylsulfoxide to the reaction mixture, but commercial enhancement reagents were ineffective. Using this RT-PCR method, cDNA amplification was successful with RNA from as few as 20 cultured tumor cells. The RT-PCR analysis was done on three invasive human colon adenocarcinomas and their paired adjacent normal mucosa. The results show MMP-1 and MMP-2 products in all three tumors, and MMP-2 detected in one of the three normal mucosa samples; TIMP-2 expression was present in two of three patients and awaits quantitative assessment of RT-PCR products.