Sweat electrolyte and cystic fibrosis mutation analysis allows early diagnosis in Brazilian children with clinical signs compatible with cystic fibrosis.

A total of 540 individuals with clinical signs suggestive of cystic fibrosis (CF) was studied. The sweat chloride was measured and the DF508, G542X, R553X, and W1282X mutations of the CF gene were screened by polymerase chain reaction (PCR). With this approach the diagnosis of CF was confirmed in 12 children, while 7 additional cases, who are heterozygous for the DF508 mutation, have had minor clinical signs.

Deficiency of alpha-actinin-3 (ACTN3) occurs in different forms of muscular dystrophy.

The alpha-actinins belong to a superfamily of cytoskeletal proteins, and their role in human genetic diseases is still unclear. Therefore, they could be good candidates for muscular dystrophies of unknown etiology. We have analyzed alpha-actinin-3 (ACTN3) in muscle biopsies from a total of 54 patients.

Familial spongiform encephalopathy associated with a novel prion protein gene mutation.

Human prion diseases include Creutzfeldt-Jakob disease, Gerstmann-Stráussler-Scheinker disease, fatal familial insomnia, and kuru. Each of these diseases has a specific clinical presentation while spongiform encephalopathy, neuronal loss, and gliosis are their neuropathological hallmarks. We studied a Brazilian family with an autosomal dominant form of dementia.

The seventh form of autosomal recessive limb-girdle muscular dystrophy is mapped to 17q11-12.

The group of autosomal recessive (AR) muscular dystrophies includes, among others, two main clinical entities, the limb-girdle muscular dystrophies (LGMDs) and the distal muscular dystrophies. The former are characterized mainly by muscle wasting of the upper and lower limbs, with a wide range of clinical severity. This clinical heterogeneity has been demonstrated at the molecular level, since the genes for six AR forms have been cloned and/or have been mapped to 15q15.

Absence of calpain 3 in a form of limb-girdle muscular dystrophy (LGMD2A).

Antibodies that recognise the muscle-specific calpain 3 (CANP3) were used in a 'blind' study to label blots of skeletal muscle from 12 control subjects and from 12 patients with various muscle diseases. Calpain 3 was clearly detected in all control muscle samples analysed, even though some of the muscle had been at room temperature for over an hour before being dissected and snap-frozen. Calpain 3 was also detected in the muscle biopsies from non-LGMD2A patients, but was absent in samples from 3 patients with LGMD2A.

Novel point mutations in the dystrophin gene.

Duchenne (DMD) and Becker (BMD) type muscular dystrophies are allelic X-linked recessive disorders caused by mutations in the gene encoding dystrophin. About 65% of the cases are caused by deletions, while 5-10% are duplications. The remaining 30% of affected individuals may have smaller mutations (point mutations or small deletions/insertions) which cannot be identified by current diagnostic screening strategies.

The phenotype of chromosome 2p-linked limb-girdle muscular dystrophy.

This study reports on a detailed clinical, electrophysiological, muscle computed tomography (CT) and laboratory investigation carried out on five families with definite linkage to chromosome 2p. Some clinical and laboratory features were common to most of the patients, such as the very high serum creatine kinase (CK) levels (mean 43.70 times the normal).

The sarcoglycan complex in the six autosomal recessive limb-girdle muscular dystrophies.

To enhance our understanding of the autosomal recessive limb-girdle muscular dystrophy (LGMD), patients from six genetically distinct forms (LGMD2A to LGMD2F) were studied with antibodies directed against four sarcoglycan subunits (alpha-, beta-, gamma-, delta-SG), dystrophin, beta-dystroglycan (beta-DG) and merosin. All patients with LGMD2A and 2B had a mild clinical course while those with a primary sarcoglycan mutation (LGMD2C to 2F) had a range of clinical severity. Dystrophin and merosin immunofluorescence pattern was positive in patients with all six AR LGMDs.

Genomic screening for beta-sarcoglycan gene mutations: missense mutations may cause severe limb-girdle muscular dystrophy type 2E (LGMD 2E).

Autosomal recessive limb-girdle muscular dystrophies (LGMDs) are genetically heterogeneous. A subgroup of these disorders is caused by mutations in the dystrophin-associated sarcoglycan complex. Truncating mutations in the 43 kDa beta-sarcoglycan gene (LGMD 2E) were originally identified in a sporadic case of Duchenne-like muscular dystrophy, and a common missense mutation (T151R) was identified independently in Indiana Amish pedigrees with a milder form of LGMD.

Mild and severe muscular dystrophy caused by a single gamma-sarcoglycan mutation.

Autosomal recessive muscular dystrophy is genetically heterogeneous. One form of this disorder, limb-girdle muscular dystrophy type 2C (LGMD 2C), is prevalent in northern Africa and has been shown to be associated with a single mutation in the gene encoding the dystrophin-associated protein gamma-sarcoglycan. The previous mutation analysis of gamma-sarcoglycan required the availability of muscle biopsies.

Autosomal recessive limb-girdle muscular dystrophy, LGMD2F, is caused by a mutation in the delta-sarcoglycan gene.

Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of inherited neuromuscular disorders characterized by proximal muscular weakness of the pelvic and shoulder girdles and a variable progression with symptoms, ranging from very severe to mild. One autosomal dominant (LGMD1A, at chromosome 5q22.3-31.

A gene which causes severe ocular alterations and occipital encephalocele (Knobloch syndrome) is mapped to 21q22.3.

Knobloch syndrome (KS), characterized by high myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities and occipital encephalocele, was recently confirmed as autosomal recessive. Here we report the assignment of the gene for this syndrome to 21q22.3 with the marker D21S171 through homozygosity mapping in a highly inbred Brazilian family with 11 affected individuals.

Linkage analysis in autosomal recessive limb-girdle muscular dystrophy (AR LGMD) maps a sixth form to 5q33-34 (LGMD2F) and indicates that there is at least one more subtype of AR LGMD.

Limb-girdle muscular dystrophies (LGMDs) represent a clinically heterogeneous group of genetic diseases characterised by progressive weakness of the pelvic and shoulder girdle muscles. An autosomal dominant form (LGMD1A) has been mapped at 5q22.3-31.

Main clinical features of the three mapped autosomal recessive limb-girdle muscular dystrophies and estimated proportion of each form in 13 Brazilian families.

Autosomal recessive limb-girdle muscular dystrophies (AR LGMD) represent a group of muscle diseases with a wide spectrum of clinical signs, varying from very severe to mild. Four different loci that when mutated cause the AR LGMD phenotype have been mapped or cloned or both: in two of them the linked families seem to have a relatively mild phenotype (LGMD2a and LGMD2b), in the third one the reported linked families show a more severe clinical course (LGMD2c), while mutations in the fourth locus may cause severe or mild phenotypes (LGMD2d). The relative proportion of each of these genetic forms among the LGMD families and whether there are other genes that when mutated cause this phenotype is unknown.

Deficiency of merosin (laminin M or alpha 2) in congenital muscular dystrophy associated with cerebral white matter alterations.

Recently, a deficiency of merosin has been reported in patients with classical congenital muscular dystrophy (CMD), while other patients, with indistinguishable clinico-pathological features, do not present this deficiency, suggesting genetic heterogeneity. The purpose of the present investigation was to assess merosin distribution and quantity in 21 clinically well characterized Brazilian CMD patients, in order to: a) estimate the proportion of merosin-deficient cases in this group of patients; b) characterize phenotypically merosin-negative, as compared to merosin-positive patients. Merosin deficiency was found in 11 patients and all the seven who had been submitted to neuroimaging studies showed evidence of periventricular dysmyelination.

Molecular characterization of further dystrophin gene microsatellites.

Microsatellites of the dystrophin gene have been used extensively in the genetic analysis of Duchenne and Becker muscular dystrophy families. The microsatellites that have been reported to date are clustered within disparate regions of the dystrophin gene, specifically at the 5'-end and in the central rod-domain. YACs encompassing the gene were screened for further microsatellites to improve the density of available genetic markers.

Absence of correlation between utrophin localization and quantity and the clinical severity in Duchenne/Becker dystrophies.

While present in the surface membrane of embryonic muscle fibers, in adult normal muscle fibers, utrophin is restricted to the motor endplate and cells of blood vessel walls. However, the observation that utrophin is maintained in the extrajunctional plasma membrane in Duchenne (DMD) and in mdx muscle fibers has led to the suggestion that excess utrophin might compensate for dystrophin deficiency in the Xp21 muscular dystrophies. In order to detect an inverse correlation of utrophin presence and clinical severity, we have assessed utrophin distribution and quantity in DMD and Becker (BMD) patients of different ages and stages of clinical severity.

Is dystrophin always altered in Becker muscular dystrophy patients?

The differential diagnosis between autosomal recessive limb-girdle (LGMD) and X-linked Becker muscular dystrophy (BMD) is very important for genetic counseling. It has been hypothesized that all BMD patients would have dystrophin alterations and dystrophin analysis could identify the Xp21 MD. Qualitatively abnormal dystrophin is easily detectable, but it is generally associated with in-frame DNA deletions or duplications.

Confirmation of the 2p locus for the mild autosomal recessive limb-girdle muscular dystrophy gene (LGMD2B) in three families allows refinement of the candidate region.

The mild autosomal recessive limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of muscle diseases. The first gene to be mapped and associated with this phenotype was a locus on 15q based on linkage analysis in families from a French geographic isolate. These results have been confirmed in other populations, but it was shown that there is genetic heterogeneity for this form of LGMD.

Analysis of the CTG repeat in skeletal muscle of young and adult myotonic dystrophy patients: when does the expansion occur?

The purpose of this investigation was to analyze the CTG expansion in muscle as compared to lymphocytes DNA in a sample of selected myotonic dystrophy (DM) patients of different ages and degrees of clinical severity, ranging from severe congenital to minimally affected. Results from the present study showed that the size of the CTG repeat was markedly larger in skeletal muscle than in lymphocytes in all DM patients. In contrast to lymphocytes, no significant correlation was found between the size of the CTG expansion in muscle and age at onset.