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Biomedical subjects

F Muntoni

Publications and source records attributed to F Muntoni.

At least 199 records · Page 11Linked to original sources
PubMed1995

Demyelinating peripheral neuropathy in merosin-deficient congenital muscular dystrophy.

It has recently been shown that merosin, a laminin variant, is deficient in a proportion of patients with congenital muscular dystrophy. Merosin is a heterotrimer composed of the alpha 2, beta 1, and gamma 1 subunits, and further studies have shown that it is the alpha 2 subunit that is deficient in these patients. Because the alpha 2 subunit is also expressed in S-merosin, found in Schwann cells, we have investigated whether peripheral nerve function is also affected in these patients. Motor nerve conduction velocities and sensory distal latencies were examined in 25 cases of congenital muscular dystrophy and the results correlated with the merosin expression in their muscle biopsies. All but two of the 10 merosin-deficient cases had reduced motor nerve conduction, whereas all the merosin-positive cases had normal results. Analysis of the biopsies of these two cases showed that they produced merosin in reduced amounts, in contrast to all other merosin-deficient patients that produced no or only traces of merosin. Sensory nerve studies showed no difference between the two groups. These results indicate that a peripheral demyelinating neuropathy is a feature of merosin-deficient congenital muscular dystrophy. The fact that the alpha 2 subunits is also expressed in Schwann cells supports the idea that the alpha 2 gene, located on chromosome 6, is the candidate gene for merosin-deficient congenital muscular dystrophy.

Adolescent↗
PubMed1995

Transcription of the dystrophin gene in normal tissues and in skeletal muscle of a family with X-linked dilated cardiomyopathy.

We recently described a family where a deletion of the dystrophin gene was associated with a severe dilated cardiomyopathy without skeletal muscle weakness. The deletion removed the muscle promoter region and the first muscle exon, but not the brain or Purkinje-cell promoters. Dystrophin was detected immunocytochemically in the skeletal muscle from this family, despite the fact that the deletion eliminated the transcriptional start site of the muscle isoform. In order to determine which promoter was driving dystrophin transcription in skeletal muscle of these individuals, we first evaluated the expression of the exon 1 of muscle, brain, and Purkinje-cell isoforms in normal human skeletal and cardiac muscles and in mouse brain and cerebellum. Our data indicate that, with the exception of minimal expression of the brain isoform, only the muscle isoform is significantly transcribed in skeletal muscle, whereas both the exon 1 muscle and brain isoforms are highly expressed in cardiac muscle. In contrast to what is observed in normal muscle, the skeletal muscle of our patients showed expression of both the brain and the Purkinje-cell isoforms. The overexpression, in skeletal muscle, of these two isoforms thus appears to be of crucial importance in preventing a myopathy in these affected males. The reason for the severe cardiomyopathy remains speculative, in the absence of dystrophin data on their heart. However, we have found in the 5' end of intron 1, a region deleted in our cases, regulatory sequences that might be of importance for dystrophin expression in various tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Readjusting the localization of merosin (laminin alpha 2-chain) deficient congenital muscular dystrophy locus on chromosome 6q2.

The laminin alpha 2-chain gene mutations (LAMA2) are responsible for about 50% of the cases of classical congenital muscular dystrophy. These patients form a clinically homogenous group presenting merosin (laminin alpha 2-chain) deficiency in muscle biopsies. The LAMA2 gene has been previously localized on 6q22-23 and the disease locus mapped in a 16 cM interval in 6q2 by homozygosity mapping. In the present report we establish, by haplotyping additional microsatellites markers in 18 consanguineous families, that LAMA2 gene is more centromeric than previously thought: between the flanking markers, D6S407 and D6S1705, distant of 3 cM. In this interval the microsatellite D6S1620 is homozygous for all the patients. The localization of LAMA2 gene was confirmed by radiation hybrid mapping. The 3 new highly informative markers can be very useful for prenatal diagnosis.

Chromosome Mapping↗
PubMed1994

Familial cardiac and skeletal myopathy associated with desmin accumulation.

We describe the case of a mentally retarded young man with marked biventricular hypertrophy, skeletal myopathy, and bilateral pes cavus, in whom desmin accumulation was documented in cardiac and skeletal muscle biopsies. Hemodynamic assessment showed a restrictive profile. A brother of the proband was similarly affected and died at the age of 24 of cardiac failure. Sudden death occurred in other six members of this family. Pedigree analysis suggested an X-linked inheritance. This observation and previous reports suggest that desmin accumulation is probably less rare than was thought in patients with unexplained hypertrophic or restrictive cardiomyopathies. Desmin accumulation should be systematically searched for in these types of cardiomyopathies, although its specificity needs to be investigated in further studies.

Adult↗
PubMed1994

Toxic effect of intraventricular interferon-alpha in subacute sclerosing panencephalitis.

Intraventricular interferon (IFN) administration has been shown to improve the course of SSPE. However, in 2 patients treated with intraventricular IFN-alpha-2a over a long period, we observed the appearance of clinical and EMG signs suggestive of upper and lower motor neuron pathology. These signs improved slightly in one patient after the discontinuation of IFN. It is suggested that this poly-peptide may act on specific kinds of nervous cells which selectively suffer together in various well-known neurological diseases.

Adolescent↗
PubMed1994

Familial cardiomyopathy, mental retardation and myopathy associated with desmin-type intermediate filaments.

The clinical and morphological findings of a familial case affected by mental retardation, severe biventricular hypertrophic cardiomyopathy and vacuolar myopathy are reported. The phenotype of this patient is similar to that described by other authors, in which a lysosomal glycogen storage disease with normal acid maltase levels was suspected. However, in our case the vacuoles were stained by several antibodies directed against various sarcolemmal proteins, such as dystrophin and spectrin, and therefore, were not of lysosomal origin. Some of these vacuoles were clearly derived from the splitting of the fibres and invagination of the extracellular space; autophagic vacuoles were not observed. The accumulation of desmin-type, intermediate filaments was demonstrated on immunocytochemistry both in the skeletal and cardiac muscles. A brother of the propositus was also affected by mental retardation, severe cardiomyopathy and died suddenly at the age of 24 yr. A cardiomyopathy and mental subnormality were also present in other male cousins of the proband, while sudden death occurred in several females relatives, whose intelligence was normal. None of these latter individuals was available for further investigation. This report expands the spectrum of desmin associated myopathy and cardiomyopathy to include a familial condition with associated mental retardation.

Adult↗
PubMed1994

Deletions in the 5' region of dystrophin and resulting phenotypes.

Deletions in the dystrophin gene give rise to both Duchenne and Becker muscular dystrophies. Good correlation is generally found between the severity of the phenotype and the effect of the deletion on the reading frame: deletions that disrupt the reading frame result in a severe phenotype, while in frame deletions are associated with a milder disease course. Rare exceptions to this rule, mainly owing to frameshift mutations in the 5' region of the gene (in particular deletions involving exons 3 to 7) which are associated with a milder than expected phenotype, have been reported previously. In order to characterise better the relationship between genotype and phenotype as a result of mutations arising in the 5' region of the gene, we have studied a large cohort of patients with small in frame and out of frame deletions in the first 13 exons of the dystrophin gene. Fifty-five patients with a deletion in this area were identified; approximately one third of them had a phenotype different from that theoretically expected. Patients were divided into two groups: (1) patients with a severe clinical phenotype despite the presence of a small, in frame deletion and (2) patients with a mild phenotype and an out of frame deletion. Noticeable examples observed in the first group were Duchenne boys with a deletion of exon 5, of exon 3, and of exons 3-13. In the second group we observed several patients with an intermediate or Becker phenotype and out of frame deletions involving not only the usual exons 3-7 but also 5-7 and 3-6. These data indicate that a high proportion of patients with a deletion in the 5' end of the gene have a phenotype that is not predictable on the basis of the effect of the deletion on the reading frame. The N-terminus of dystrophin has at least one actin binding domain that might be affected by the small, in frame deletions in this area. The effect of the in frame deletions of exon 3, 5, and 3-13 on this domain might account for the severe phenotype observed in these patients. Other mechanisms, such as unexpected effect of the deletion on splicing behaviour, might, however, also be implicated in determining the phenotype outcome.

Adolescent↗
PubMed1993

Muscular weakness in the mdx mouse.

mdx mice are believed to be virtually free from neuromuscular symptoms, despite the presence of a degenerative/regenerative process that involves all skeletal muscles. We analyzed both the spontaneous motility and treadmill motor activity of mdx mice aged 15 days to 6 months. Our results indicate that there is an early period, between the end of the second and up to the fifth week of life, when mdx mice experience extreme weakness. After this critical period, both spontaneous motility and endurance of mdx mice, although lower than those of controls, do not show statistically significant differences up to 6 months of age. We also carried out a detailed histological analysis of proximal and distal muscle groups in mdx mice during this early critical motility period. The occurrence of extensive necrosis followed by regeneration and involving proximal muscles before distal ones was documented in mice as young as 16-17 days of age and reached a peak at day 18. We conclude that dystrophin deficiency induces muscle degeneration and significant weakness in mdx mice, but only in an early period. Later on, during development, mdx mice adapt to the lack of this protein and do not show detectable in vivo functional muscle impairment up to 6 months of age.

Aging↗
PubMed1993

Role of predisposing and protective HLA-DQA and HLA-DQB alleles in Sardinian multiple sclerosis.

OBJECTIVE: To study the role of HLA genes in susceptibility and resistance to multiple sclerosis (MS) in Sardinian patients. To verify whether HLA-DQA and HLA-DQB genes differed between unrelated (MSU) and related (MSR) patients, and whether relapsing-remitting and chronic progressive forms of MS are immunogenetically distinct entities. DESIGN: Case-control study of HLA-DQA and HLA-DQB gene frequency. SETTING: All patients investigated were followed up by our MS referral centers. PATIENTS: The study involved 116 MSU patients, 67 of whom had a relapsing-remitting form (MSr), 28 of whom had a chronic progressive from-the-onset form (MSc), and 21 of whom had a benign form (MSb), 32 patients with MSR, 19 parents and 27 healthy siblings of patients with MSR, and 86 controls. Selection of patients was random, while control subjects came from families without known immunologic diseases. All patients had definite MS. MAIN OUTCOME MEASURE: Statistical analysis of gene frequencies was conducted with the chi 2 test with correction (Pc) for the alleles investigated, as was decided before the study began. RESULTS: The DQA1*0301 allele was found to be increased in patients (MSU vs controls, Pc = .008; patients with MSc vs controls, Pc = .001; patients with MSR vs controls, Pc = .02; and parents vs controls, Pc = .04), while the DQA1*0102 allele was found to be diminished in patients with MSr vs controls (Pc = .001). Among the DQB genes, the DQB1*0502 allele was diminished in patients with MSr vs controls (Pc = .04), while the sum of DQB1*0201 and *0302 alleles was significantly increased in patients with MSR vs controls (Pc = .003). CONCLUSION: Both HLA-DQA and HLA-DQB genes influence genetic susceptibility and resistance to MS. The roles of these genes differ in the various forms of MS. Patients with MSU and MSR both share HLA-DQA susceptibility genes.

Adolescent↗
PubMed1993

Identification of a novel T-insertion polymorphism at the DMD locus.

We have identified a novel T-insertion polymorphism located in the second intron of the dystrophin gene. This polymorphism should prove useful in linkage studies in Duchenne and Becker muscular dystrophy families in addition to the previously described markers.

DNA Transposable Elements↗
PubMed1993

Combinations of specific DRB1, DQA1, DQB1 haplotypes are associated with insulin-dependent diabetes mellitus in Sardinia.

The Sardinian population has an extremely high incidence of IDDM (30.2 of 100.000 in the age group of 0-14 years). This study reports the molecular characterization of HLA class II genes in 120 IDDM sporadic patients and 89 healthy subjects of Sardinian origin. Compared with other Caucasians, both Sardinian patients and controls had an unusual distribution of haplotypes and genotypes. In particular, there was a high gene frequency of the DRB1*0301, DQA1*0501, DQB1*0201 susceptibility haplotype both in patients (0.58) and controls (0.23) while a reduction of the DRB1*1501, DQA1*0102, DQB1*0602 protective haplotype (0.03) was observed in the healthy population. This distribution may partially explain the high incidence of IDDM reported in Sardinia. The analysis of the DQ beta 57 and DQ alpha 52 residues showed that the absence of Asp 57 and the presence of Arg 52 were associated with IDDM in a dose-response manner. On the other hand, we found that (a) a very similar distribution of these residues was found when comparing Sardinians with another healthy Caucasian population from the same latitude but with a lower rate of IDDM incidence; (b) several genotypes encoding the identical DQ alpha 52/DQ beta 57 phenotype carried very different relative risks; and (c) the DRB1*0403, DQA1*0301, DQB1*0304 haplotype (DQ beta 57 Asp-neg and DQ alpha 52 Arg-pos) was found in 40% of the DR4-positive controls but not in patients (p = 0.00034), while the DRB1*0405, DQA1*0301, and DQB1*0302 haplotype carrying the same residues at the same positions was found in 70% of the DR4-positive patients and in only one control (p = 0.00003). These findings suggest that IDDM susceptibility cannot be completely explained by the model in which only DQ alpha 52 and DQ beta 57 residues are taken into account.

Adolescent↗
PubMed1993

Germinal mosaicism in a Duchenne muscular dystrophy family: implications for genetic counselling.

In this study we describe a three-generation family in which two siblings were affected by Duchenne muscular dystrophy (DMD). Immunohistochemical analysis of muscle dystrophin and haplotype analysis of the DMD locus revealed that the X chromosome carrying the DMD gene was transmitted from the healthy maternal grandfather to his three daughters, including the proband's mother. These findings indicate that the grandfather was a germinal mosaic for the DMD gene. The definition of the carrier status in two possible carriers led us to give accurate genetic counselling and to prevent the birth of an affected boy. The results of this study demonstrate the usefulness of haplotype analysis and immunohistochemical muscle dystrophin studies to detect hidden germinal mosaicism and to improve genetic counselling.

Dystrophin↗
PubMed1993

Diagnosis of DMD carrier status in a family with no known affected males.

A 30-year-old woman and her two-year-old daughter were found by chance to have moderately raised serum creatine kinase (CK) levels. Since the mother was pregnant, the authors investigated the possibility that the two females were carriers of the common Duchenne muscular dystrophy (DMD) gene. No immunohistochemical abnormality was detected in the mother, but in the daughter a clear mosaic pattern of dystrophin positive and negative fibres was found, indicating carrier status for DMD. These data indicate that a diagnosis of DMD carrier status can be made even in families without a positive history for this disorder; therefore, immunocytochemical studies, using antidystrophin antibodies, should be performed on all females with raised CK levels, including the youngest.

Child, Preschool↗
PubMed1993

A dystrophin-immunoreactive protein in mammalian brain.

Dystrophin is expressed only in muscle and brain, but is absent from all tissues of the adult mdx mouse, a mutant with a single base substitution in the dystrophin gene. The brains of both normal and mdx mice contain a protein of approximately 230 kDa that is recognised by anti-dystrophin antibodies raised to the N-terminal region of the rod-like domain. Although the N-terminal and central rod regions of dystrophin share structural homologies with spectrin, the 230-kDa protein represents neither of the presently described forms of brain spectrin by a variety of criteria (molecular weight, cerebellar localisation, and developmental regulation) and is distinct from the product of the dystrophin gene. Studies of mdx and normal mouse brain show different postnatal developmental regulation of the 230-kDa dystrophin-immunoreactive protein.

Aging↗
PubMed1993

Dystrophin analysis using a panel of anti-dystrophin antibodies in Duchenne and Becker muscular dystrophy.

Dystrophin, the protein product of the Duchenne muscular dystrophy (DMD) gene, was studied in 19 patients with Xp21 disorders and in 25 individuals with non-Xp21 muscular dystrophy. Antibodies raised to seven different regions spanning most of the protein were used for immunocytochemistry. In all patients specific dystrophin staining anomalies were detected and correlated with clinical severity and also gene deletion. In patients with Becker muscular dystrophy (BMD) the anomalies detected ranged from inter- and intra-fibre variation in labelling intensity with the same antibody or several antibodies to general reduction in staining and discontinuous staining. In vitro evidence of abnormal dystrophin breakdown was observed reanalysing the muscle of patients, with BMD and not that of non-Xp21 dystrophies, after it has been stored for several months. A number of patients with DMD showed some staining but this did not represent a diagnostic problem. Based on the data presented, it was concluded that immunocytochemistry is a powerful technique in the prognostic diagnosis of Xp21 muscular dystrophies.

Adolescent↗