Sporadic vascular dementia as clinical presentation of a new missense mutation within exon 7 of NOTCH3 gene.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetic disease characterized by ischemic stroke with early onset, migraine, seizures, and vascular dementia. CADASIL is associated with mutations within NOCT3 gene, mainly clustered in exons 3 and 4. We report a case of CADASIL presenting progressive subcortical dementia in the sixth decade. Neither family history, nor acute ischemic events were present. MRI findings were typical for CADASIL. NOTCH3 analysis disclosed a new missense mutation within exon 7, leading to the substitution of cysteine 366 with a tryptophan (Cys366Trp). Our finding suggests CADASIL diagnosis must be considered in patients with vascular dementia also in absence of stroke-like events and of family history.

Alpha-sarcoglycan deficiency featuring exercise intolerance and myoglobinuria.

An 8-year-old boy was referred for recent onset of easy fatigue. He showed hyperCKemia and mild scapular winging. Muscle biopsy on the quadriceps muscle demonstrated slight fibre size variability. Dystrophin was normally distributed, carnitine palmitoyl transferase and glycolytic enzymes had normal activities. In the following years the patient developed exercise intolerance and myoglobinuria. Immunohistochemistry showed marked reduction of alpha-sarcoglycan, confirmed by Western blotting. Molecular analysis revealed compound heterozygosity with Arg284Cys and Glu137Lys substitutions, corresponding to nucleotide changes C850 T and G409 A in the gene. At present the patient, 20 years old, shows mild proximal weakness with prominent involvement of the paraspinal muscles, dorsal kyphosis and lumbar hyperlordosis. Exercise intolerance and myoglobinuria, already described in Becker muscular dystrophy, should be also considered among the possible presentations of sarcoglycan deficiencies.

MERRF/MELAS overlap syndrome in a family with A3243G mtDNA mutation.

Four members of a family were found to carry the A3243G mtDNA mutation. Clinical features varied from typical MELAS to myoclonic epilepsy to simple deafness without neurological signs. Several other members of the family had symptoms consistent with a mitochondrial disease. Muscle biopsy in 3 of the 4 patients showed the most prominent mitochondrial alterations with partial deficiency of cytochrome c oxidase in the case with the mildest phenotype. Mitochondrial DNA analysis detected a variable percentage of A3243G mutation, roughly correlating with the phenotype. The interesting feature of the family lies in the great intrafamilial variability of the severity of clinical expression, encompassing MELAS and MERRF features, associated with the A3243G mtDNA mutation. A search for the most common mtDNA mutations is recommended in all patients featuring incomplete MELAS or MERRF syndromes and in all familial cases presenting minimal clinical signs.

Late onset and very mild course of Xp21 Becker type muscular dystrophy.

We report a case of late onset of Becker's muscular dystrophy (BMD), diagnosed at the age of 60, which showed a very mild clinical course. Remarkably, the immunohistochemical pattern did not show significant alterations, while Western blotting disclosed low molecular weight dystrophin. DNA analysis showed a deletion of the exons 45-53 of the Xp21 gene, which is fairly typical of Becker's muscular dystrophy but not predictable of clinical course. The possibility of Xp21 muscular dystrophy must be considered in all myopathies of uncertain cause, also in elderly patients.

A new mtDNA mutation associated with a progressive encephalopathy and cytochrome c oxidase deficiency.

The authors describe a novel pathogenic G5540A transition in the mitochondrial transfer RNA (tRNA)Trp gene of a sporadic encephalomyopathy characterized by spinocerebellar ataxia. Clinical features also included neurosensorial deafness, peripheral neuropathy, and dementia. Biochemistry revealed a severe reduction of cytochrome c oxidase (COX) activity. Single-fiber PCR demonstrated higher levels of mutant genomes in COX-negative ragged red fibers than in normal fibers. These findings confirm that COX is more susceptible than other respiratory chain complexes to mutations in the mitochondrial tRNATrp gene.

Unusual clinical expression of dystrophinopathy in a female, mimicking a congenital myopathy.

A 25-year-old woman with negative family history and delayed motor development presented hypotrophy of the right lower limb and calf hypertrophy since age 7 and she complained of muscle weakness since 23. Neurological examination showed a thin elongated face, high-arched palate, high-pitched voice, proximal wasting and weakness, impairment of distal muscles in the lower limbs. CK was 3, 034 U/l, EMG showed a myopathic pattern. Muscle biopsy displayed dystrophic features with diffuse dystrophin deficiency; immunoblotting demonstrated quantitative reduction of the protein and normal molecular weight. Lyonization study showed skewed X-inactivation with the maternal X active. Seven years' follow-up did not show progression of the disease.

Variable histological expression of dystrophinopathy in two females.

We report two carriers of Xp21 muscular dystrophy with unusual clinical manifestations and striking variability of dystrophin deficiency within the same muscle biopsy. The first patient was a 60-year-old nun with recent onset of cramps and proximal weakness, mimicking an acquired myopathy. Muscle biopsy disclosed slight alterations in one sample and severe dystrophic changes in another; dystrophin was absent in 7% fibers in the former specimen and in 60% in the second. X inactivation was skewed with 90% cells inactivating the same X chromosome. The second patient was a 17-year-old girl with hyperCKemia, learning disability and a family history of X-linked muscular dystrophy. Muscle biopsy displayed slight fiber size variability and some internal nuclei; dystrophin was absent only in one muscle fiber. A second sample with the same morphological features demonstrated dystrophin deficiency with mosaic distribution. The pattern of X inactivation was normal. These cases emphasize the variability of histopathological changes and dystrophin deficiency in Xp21 muscular dystrophy carriers and the risk of sampling errors in muscle biopsy.

Systematic use of dystrophin testing in muscle biopsies: results in 201 cases.

We studied dystrophin with both immunohistochemistry and immunoblotting in 201 muscle biopsies stored in liquid nitrogen during the period 1985-92. The systematic use of dystrophin testing combined with DNA analysis and with 3-10 years follow-up of the patients yielded a significant modification of the diagnoses made previously and identified dystrophinopathies with unusual expression and course. Seventeen out of 152 (11.18%) diagnoses in males and 8 out of 49 (16.32%) in females were modified by dystrophin testing. Most diagnostic errors (9 out of 27 diagnoses) were in the group Becker muscular dystrophy-limb girdle muscular dystrophy, confirming the clinical overlap of the two diseases. Unusual expressions of dystrophinopathy included muscular dystrophy with early elbow contractures (two patients), recurrent myoglobinuria (one patient), dilating cardiomyopathy (two patients), myoglobinuria and associated dilating cardiomyopathy (one patient), very late-onset benign myopathy (two patients and one manifesting carrier) and congenital myopathy (one manifesting carrier). In the group 'idiopathic hyper-CKaemia', we did not find any dystrophinopathy in 34 males, whereas five out of nine females were found to be carriers. Immunohistochemical analysis of dystrophin using the monoclonal antibody against the C-terminus detected 99% of protein defects and was found to be the most cost-effective way of revealing dystrophinopathies. The combined use of immunohistochemical analysis with the antibody against the C-terminus and immunoblotting with the antibody against the core of the protein appears to be a highly reliable diagnostic approach (100% detection rate).

Muscle apoptosis in humans occurs in normal and denervated muscle, but not in myotonic dystrophy, dystrophinopathies or inflammatory disease.

Recent data suggest that death of muscle cells during development and in selected pathological conditions occurs via apoptosis. We investigated the occurrence of apoptosis in normal and pathological human skeletal muscle, using in situ end-labeling (ISEL) to detect DNA fragmentation, and immunohistochemistry for the expression of tissue transglutaminase and interleukin-1beta-converting enzyme (ICE)-like proteases. In normal subjects, apoptotic myonuclei were occasionally observed as evidence of normal tissue turnover. Myonuclear apoptosis due to a deficit of trophic support from nerve cells also occurred in spinal muscular atrophies. No apoptosis of muscle cells was found in dystrophinopathies, myotonic dystrophy and inflammatory myopathies, suggesting that death of myofibers in those conditions is not due to activation of a gene-directed program of death. In dystrophinopathies and inflammatory myopathies, apoptosis was found in interstitial mononuclear cells, as a likely mechanism of clearance of the inflammatory infiltrates.

Quantitative and qualitative alterations of dystrophin are expressed in muscle cell cultures of Xp21 muscular dystrophy patients (Duchenne and Becker type).

The authors studied skeletal muscle cell cultures from four control subjects, two patients with Duchenne muscular dystrophy, two Duchenne carriers and three patients with Becker muscular dystrophy with different phenotypes. Western blotting was performed on well-differentiated myotubes and compared with the results obtained in muscle tissue. In all cultures the band of dystrophin closely corresponded to the one observed in muscle tissue: both quantitative and qualitative defects were observed. This confirms the early expression of the Xp21 gene defect in uninnervated muscle cultures and supports the usefulness of muscle cultures both in diagnostic procedure and as a model to study the disease.

Carrier detection of Duchenne muscular dystrophy through analysis of DNA from deciduous teeth of a dead affected child.

The sister of a child affected by Duchenne muscular dystrophy (DMD) was referred for genetic counselling to assess the risk of her being a carrier. Her brother had died 15 years previously at the age of 8. There were no other affected males in the family. There were no methods for DNA investigation at the time of the child's death and the family had never been studied for linkage with polymorphic probes on the chromosomal region Xp21. The only tissue from which an assessment of the risk could be made by DNA linkage analysis was two of the child's deciduous teeth that the parents had kept. DNA was extracted using a protocol described for the recovery of ancient DNA from museum specimens and archaeological finds. Multiplex amplification did not reveal deletions in 19 exons spanning the hot-spot regions for deletions within the dystrophin gene in Xp21. Linkage analysis using three highly polymorphic microsatellites demonstrated that the sister had not received the X chromosome borne by her brother. These results show that DNA extracted from teeth is a reliable source for molecular diagnosis.

Unusual expression and very mild course of Xp21 muscular dystrophy (Becker type) in a 60-year-old man with 26 percent deletion of the dystrophin gene.

A 54-year-old farmer with a negative family history had had mild proximal weakness for the previous 4 years. Clinical examination showed marked scoliosis, barrel-shaped chest, diffuse hypotrophy, and mild proximal weakness. Creatine kinase was 938 U/l; electrocardiography and echocardiography were normal. EMG disclosed myopathic changes. Muscle biopsy showed slight, nonspecific alterations. Dystrophin was present and normally distributed with antibodies against the C-terminal and N-terminal, whereas it was not recognized by the antibody against the rod domain. Western blotting detected an abnormal molecular weight protein of 320 kd (normal, 427 kd). Southern blot analysis revealed a deletion from exon 21 to exon 44, corresponding to 26% of the coding region of dystrophin. Six years' follow-up did not disclose progression of the muscle disease.

Metachromatic dye-Ca++ATPase method in pathological muscle: a study of 382 muscle biopsies.

The metachromatic dye-Ca++ATPase method, that in normal muscle distinguishes fiber types on the basis of their metachromatic or orthochromatic staining, was applied to 382 pathological muscle biopsies. Results were compared in serial sections with those obtained with the conventional ammonium sulphide method. In pathological muscle the metachromatic dye-Ca++ATPase method confirms the advantages already showed in normal muscle: fast and easy performance, neat fiber typing, simultaneous staining of nuclei. Moreover in pathological muscle the metachromatic dye-Ca++ATPase method showed some muscle changes which are missed by the conventional ammonium sulphide one, namely central nuclei, macrophagic invasion and some structural abnormalities. This allows immediate correlation between those alterations and fiber typing.

Mutations in the ryanodine receptor gene in central core disease and malignant hyperthermia.

Central core disease (CCD) of muscle is an inherited myopathy which is closely associated with malignant hyperthermia (MH) in humans. CCD has recently been shown to be tightly linked to the ryanodine receptor gene (RYR1) and mutations in this gene are known to be present in MH. Mutation screening of RYR1 has led to the identification of two previously undescribed mutations in different CCD pedigrees. One of these mutations was also detected in an unrelated MH pedigree whose members are asymptomatic of CCD. The data suggest a model to explain how a single mutation may result in two apparently distinct clinical phenotypes.

Adult onset nemaline myopathy: a distinct nosologic entity?

A 61-year-old woman presented progressive distal weakness and wasting of her upper limbs spreading to the shoulder girdle and to the neck muscles. Creatine kinase, cerebrospinal fluid, spinal X-ray and spinal nuclear magnetic resonance were normal. Electromyography showed myopathic alterations. Muscle biopsy showed abundant rods in many fibres. Prednisone 75 mg/die for two months did not modify the symptoms.

Exercise intolerance and recurrent myoglobinuria as the only expression of Xp21 Becker type muscular dystrophy.

A 9-year-old boy complained of exertional myalgias and described two episodes of myoglobinuria. His family history was negative for neuromuscular diseases. The findings of a neurological examination were normal. Serum creatine kinase was increased, ECG was normal, EMG showed slight "myopathic" signs. Muscle biopsy disclosed a small group of basophilic fibres as the only abnormality. Muscle glycolytic enzymes and carnitine palmitoyl transferase were normal. Immunoblotting using antidystrophin antibody demonstrated a protein with low molecular weight. Genomic DNA analysis showed a deletion of the HindIII fragments spanning from exon 45 to exon 48. Eight years after the first observation the patient has diffuse muscle hypertrophy without muscle weakness.

Congenital muscular dystrophy associated with familial junctional epidermolysis bullosa letalis.

A 20-year-old patient was born with epidermolysis bullosa and a severe, slowly progressive muscle disease. Skin biopsy demonstrated junctional epidermolysis bullosa. Muscle biopsy demonstrated degenerative changes with increase in connective tissue, fibre size variability, rods and cytoplasmic bodies, central nuclei. In muscle biopsy dystrophin, chondroitin unsulphate, chondroitin 4-sulphate, chondroitin 6-sulphate, heparan sulphate, collagen III, collagen IV and VI, laminin, and fibronectin were normally distributed. This is the first report of the association of a form of congenital muscular dystrophy with junctional epidermolysis bullosa and, together with the previous reports of muscle involvement in epidermolysis bullosa simplex and dystrophica, it suggests the existence of a syndrome characterized by the contemporaneous presence of skin and muscle involvement.

Clinical spectrum of McArdle disease: three cases with unusual expression.

Three cases of myophosphorylase deficiency with unusual clinical expression are presented. The 1st had clinical characteristics suggesting a mild congenital myopathy, and the patient never experienced cramps or myalgias. The 2nd had a slowly progressive myopathy without cramps or myoglobinuria which was detected by chance. The 3rd presented with myoglobinuria and acute renal failure, unrelated to a triggering effort, and with permanent weakness and wasting. In all cases, muscle biopsy demonstrated a vacuolar myopathy with free glycogen increase and absence of myophosphorylase activity, confirmed by biochemical assays. The cases confirm the wide clinical spectrum of McArdle disease.