An autosomal dominant type of congenital muscular dystrophy

A family with an autosomal dominant type of congenital muscular dystrophy (CMD) will be reported. In general, an autosomal recessive mode of inheritance is accepted for CMD. In 1980, Kalyanaraman et al reported another family with an autosomal dominant CMD with possible involvement of the central nervous system (CNS). Our report concerns a father and daughter suffering from CMD without CNS involvement. The histological findings, especially some mitochondrial abnormalities in the muscle biopsy were remarkable.     

Adult-onset autosomal dominant limb-girdle muscular dystrophy

We describe a kindred with a rare autosomal dominant myopathy limited to the limb-girdle muscles, beginning insidiously any time from the late second through the sixth decades and followed by slow progression. Pelvifemoral precedes scapulohumeral weakness, and proximal appendicular involvement antedates limited distal paresis. Expressivity varies and includes an asymptomatic myopathy (preclinical or subclinical) and a nonmanifesting carrier state that extends well into the eighth decade. A variety of nonspecific changes are present in muscle on light, enzyme histochemical, and electron microscopic examination; of these changes, "rimmed" or autophagic vacuoles are the most characteristic. We identified one very similar previously reported genealogy. The similarities between the two unrelated families clearly establish this dystrophic process as a distinct genetic entity; their differences suggest genetic heterogeneity.     

Emery-Dreifuss muscular dystrophy with autosomal dominant transmission

A woman with early-onset, slowly progressive, humeroperoneal muscle weakness had marked restriction of neck flexion with contracture at the elbows. She developed exertional dyspnea at age 25, atrial fibrillation with slow ventricular rate was discovered, and a cardiac pacemaker was implanted. Her father had a similar disorder. There is at least one other report of autosomal dominant transmission of this clinical picture, which had previously only been reported as Emery-Dreifuss muscular dystrophy with X-linked recessive inheritance. Thus, more than one mode of inheritance is possible for this unusual and distinctive form of muscular dystrophy.     

Desmin immunolocalisation in autosomal dominant Emery-Dreifuss muscular dystrophy

Autosomal dominant Emery-Dreifuss muscular dystrophy (AD-EDMD) is one of a number of allelic disorders caused by mutations in the nuclear lamina proteins, lamins A and C. The disorder is characterised by the early onset of skeletal muscle weakness and joint contractures and later, by dilated cardiomyopathy and cardiac arrythmias. Although the pathophysiology is not understood, one theory suggests that disordered structural organisation at weakened nuclei in contractile cells may underlie the disease. Previous work shows that mice deficient in lamin A/C develop similar skeletal and cardiac muscle signs to patients with AD-EDMD and ultrastructural examination of muscle from these mice shows abnormal localisation of desmin. We hypothesised therefore that desmin localisation may be abnormal in muscle or cells from patients with AD-EDMD and/or in cells expressing mutant lamins. In order to evaluate this, desmin immunolocalisation was determined in skeletal muscle biopsy sections from patients with AD-EDMD and cell lines including MyoD-transfected fibroblast-derived myotubes from AD-EDMD patients and murine embryonic stem cell-derived cardiomyocytes stably transfected with mutant human lamin A. Ultrastructural examination of patient muscle was also performed. Desmin was expressed and localised normally in patient muscle and cell lines and ultrastructural examination was similar to controls. These results fail to provide any evidence that dominant mutations in lamin A/C lead to a disorganisation of the desmin associated cytoskeleton.     

Benign muscular dystrophy with autosomal dominant inheritance.

A slowly progressive myopathy was discovered in a family in four successive generations. Eight patients (four female, four male) from three generations were examined and they showed muscle weakness affecting predominantly proximal, but also distal, muscles. Two patients had unequivocal findings in childhood, the others showed myopathy in their twenties or thirties. Working ability was lost in physically demanding jobs in the thirties, but activities of daily living were still preserved. Elbow contractures, tight heel cords and contractures of the interphalangeal joints were frequent. Serum CK activity was usually mildly elevated and electromyographic examinations revealed myopathic changes. Histopathological changes were compatible with moderately advanced muscular dystrophy in two patients, the six others had mild myopathic changes.     

Limb girdle muscular dystrophy with autosomal dominant inheritance

We describe a patient suffering from limb-girdle muscular dystrophy with autosomal dominant inheritance proved by the presence of other similar cases in both sexes scattered over 4 generations of his family tree. In all patients the symptoms appeared in adult age and pelvi-femoral preceded scapulo-humeral involvement. Clinical expressivity has been variable, but rather benign without any reduction in life expectancy. Myopathic changes with vacuoles were present in muscle on light and electron microscopic examination. In the literature we found at least another 5 genealogies with autosomal dominant LGMD which had similar clinical and pathological features to those of our patient.     

Linkage studies in autosomal dominant facioscapulohumeral muscular dystrophy

Linkage studies were undertaken in 120 individuals from 10 kindreds with autosomal dominant facioscapulohumeral muscular dystrophy using 35 different marker genes. No linkage was found. The highest lod score was 1.438 for the immunoglobulin heavy chain gene cluster (IGH) at a recombination fraction of 0.2. IGH is located on the long arm of chromosome 14. Based on scores of other marker genes and on a recombination map of chromosome 14, the probability that the gene for facioscapulohumeral muscular dystrophy is located on chromosome 14 is estimated to be approximately 6%.     

Chromosome 12-linked autosomal dominant scapuloperoneal muscular dystrophy

Scapuloperoneal syndromes are characterized by their distribution of muscle weakness and wasting. The reported pattern of inheritance has been variable. Both neurogenic and myopathic forms of autosomally dominantly inherited scapuloperoneal syndrome have been described. It has been suggested that these are variants of other neuromuscular diseases. We examined 44 members from a family with 14 members affected with a scapuloperoneal syndrome. Physiological and histological analysis implied that this condition is predominantly myopathic. Linkage analysis was done to confirm the genetic etiology of the disease in this family and to evaluate the possibility that it is an allelic variant of other neuromuscular diseases. Genetic analysis demonstrated linkage of the disease to chromosome 12, which makes it genetically distinct from other loci known to cause neuromuscular disease. Muscle fibers with hyaline desmin-containing cytoplasmic inclusions in combination with focal myopathic changes may be a disease-specific morphological marker of the disease.     

Clinical and genetic investigation in autosomal dominant limb-girdle muscular dystrophy

Limb-girdle muscular dystrophy is a syndrome of progressive myopathic weakness affecting shoulder and hip girdle and proximal arm and leg muscles. The disease occurs either sporadically or inherited as an autosomal recessive trait. Autosomal dominant inheritance is rare. We report a large family with apparent autosomal dominant inheritance. Sixteen members were affected with a disease characterized by proximal weakness, leg greater than arm, onset in the third decade, elevated CK and CK MB levels, and myopathic EMGs and muscle biopsies. Linkage analysis revealed no conclusive linkage.     

A newly recognized autosomal dominant limb girdle muscular dystrophy with cardiac involvement

Sixty-five members of three families with limb girdle muscular dystrophy (LGMD) underwent neurological, cardiological, and ancillary investigations. Thirty-five individuals were diagnosed as having slowly progressive autosomal dominant LGMD. Symmetrical weakness started in the proximal lower limb muscles, and gradually upper limb muscles also became affected. Early contractures of the spine were absent. Contractures of elbows and Achilles tendons were either minimal or late. Serum creatine kinase activity was normal to moderately elevated. Electromyogram and muscle biopsy were consistent with a mild muscular dystrophy. Cardiological abnormalities, found in more than one-half the patients, included dysrhythmias and atrioventricular (AV) conduction disturbances presenting as bradycardia, syncopal attacks necessitating pacemaker implantation, and sudden cardiac death. There was a significant relation between the severity of AV conduction disturbances and age. In nearly all patients, neuromuscular symptomatology preceded cardiological involvement. The early recognition of this previously not described, autosomal dominant LGMD with life-threatening cardiac involvement offers an opportunity for therapeutic intervention.     

Benign congenital muscular dystrophy with autosomal dominant heredity: problems of classification

Summary A family with autosomal dominant congenital muscular dystrophy affecting members of both sexes in three generations is described; a father and his two sons were studied. The onset of symptoms was in early childhood and progression, if any, was slow. The proximal limb muscles, the sternocleidomastoid and anterior tibial muscles were affected. One patient had torticollis and all had heel-cord shortening. An electrophysiological examination showed myopathy. There was no cardiomyopathy. Creatine kinase (CK) was elevated, and a histological study revealed a necrotizing myopathy with pronounced regeneration and formation of aberrant myofibrils (ringbinden) and fibrosis.     

Selective muscle involvement on magnetic resonance imaging in autosomal dominant Emery-Dreifuss muscular dystrophy

OBJECTIVE: The aim of this study was to evaluate the spectrum of muscle involvement on MRI in patients with autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD2) due to mutations in the lamin A/C gene and to compare it to the pattern found in other conditions with similar phenotype. PATIENTS AND METHODS: Nine patients with a diagnosis of EDMD2 had MRI scanning of their leg muscles. Seven other patients, four with the X-linked form of Emery-Dreifuss muscular dystrophy (EDMD) and three with an Emery-Dreifuss-like phenotype but no detectable mutations in either the emerin or the lamin A/C gene were also scanned as disease controls. RESULTS: All patients with EDMD2 showed a characteristic involvement of the posterior calf muscles. The medial head of the gastrocnemius was always predominantly involved while the lateral head was relatively spared. This pattern was more obvious in mildly affected patients in whom the other calf muscles were spared or only mildly involved but was also recognisable in the patients with more advanced disease. In contrast, none of the patients with the X-linked EDMD or with Emery-Dreifuss-like phenotype but no mutation in either genes showed this pattern of muscle involvement. CONCLUSIONS: Our results suggest that patients with EDMD2 have a specific pattern of muscle involvement and that muscle MRI can be used, in combination with other techniques, to distinguish various genetic forms of Emery-Dreifuss muscular dystrophy.     

Familial adult-onset muscular dystrophy with leukoencephalopathy.

We report on 3 siblings with an adult-onset, predominantly distal muscle weakness. In the female index patient this was associated with epilepsy and a progressive spastic ataxic gait, while the 2 other siblings had no appreciable clinical nervous system involvement. Additional investigations revealed muscular dystrophy and leukoencephalopathy in all 3 siblings. We conclude that this familial adult-onset muscular dystrophy associated with leukoencephalopathy represents a newly recognized autosomal recessive syndrome.     

Isolated noradrenergic failure in adult-onset autosomal dominant leukodystrophy

We evaluated the autonomic control of the cardiovascular system and the skin innervation of a patient from a new Italian family with a genetically proven diagnosis of adult-onset autosomal dominant leukodystrophy (ADLD) due to lamin B1 gene duplication. Cardiovascular reflexes and pharmacological assessment indicated a selective sympathetic failure, sparing cardiovagal function. Microneurography revealed absent sympathetic activity. The evaluation of autonomic innervation of skin annexes showed severely depleted and morphologically abnormal noradrenergic dopamine-β-hydroxylase (DβH) immunoreactive fibres with preserved cholinergic vasoactive intestinal polypeptide (VIP) immunoreactive fibres. This peculiar autonomic dysfunction may represent a hallmark for ADLD.     

Nuclear changes in skeletal muscle extend to satellite cells in autosomal dominant Emery-Dreifuss muscular dystrophy/limb-girdle muscular dystrophy 1B

Autosomal forms of Emery-Dreifuss muscular dystrophy (AD-/AR-EDMD) and limb-girdle muscular dystrophy type 1B (LGMD1B) are caused by mutations in the gene encoding A-type lamins (LMNA). A-type lamins are major components of nuclear lamina and known to have important roles in maintaining nuclear integrity. LMNA mutations are also suggested to cause reduced myogenic differentiation potentials, implying that satellite cell nuclei in AD-EDMD/LGMD1B are likewise affected. We examined nuclear changes of skeletal muscles including satellite cells from four patients with AD-EDMD/LGMD1B by light and electron microscopy. We found that 92.5 ± 5.0% of myonuclei had structural abnormalities, including shape irregularity and/or chromatin disorganization, and the presence of peri-/intranuclear vacuoles. Chromatin changes were also observed in 50% of the satellite cell nuclei. Increased number of Pax7-positive nuclei, but fewer number of MyoD-positive nuclei were seen on immunohistochemical analyses, suggesting functional alteration of satellite cells in addition to the nuclear morphological changes in AD-EDMD/LGMD1B.     

Autosomal recessive distal muscular dystrophy

The distal myopathies include autosomal dominant, autosomal recessive, and sporadic disorders. Two of the recessive disorders are considered to be definitive entities: Miyoshi's myopathy, which has an early adult onset and first involves the calf muscles, and distal myopathy with rimmed vacuoles.We here describe the cases of two sisters and compare them with previously reported cases. The disorder in our patients is characterised by: a) autosomal recessive inheritance; b) onset in early adult life; c) initial involvement of the tibialis anterior and peroneal muscles; d) subsequent involvement of the calf muscles spreading to the proximal muscles of the legs and, later, the arms; e) a moderately disabling evolution over a period of 10–12 years; f) marked and stably high serum levels of CK and other enzymes; g) EMG evidence of myopathic damage, with fibrillation at rest; and h) a histological picture of dystrophic myopathy, with atrophy of mainly type 2 fibres.We think that this syndrome is different from the two forms of autosomal recessive distal myopathy mentioned above.

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Sommario Le miopatie distali comprendono forme familiari a trasmissione autosomica dominante e autosomica recessiva e casi sporadici. Due sono le entità nosografiche autosomiche recessive identificate: la Miopatia di Miyoshi ad esordio giovanile e con compromissione iniziale dei muscoli del polpaccio, e la Miopatia distale con fibre vacuolate.Descriviamo in questa sede i casi di due sorelle e li confrontiamo con quelli della letteratura. La malattia delle nostre pazienti è caratterizzata da: a) Trasmissione autosomica recessiva; b) esordio in età giovanile; c) compromissione iniziale dei muscoli tibioperoneali; d) successiva compromissione dei muscoli dei polpacci, e poi nell'ordine dei gruppi prossimali degli arti inferiori e superiori; e) evoluzione mediamente invalidante in un tempo di 10–12 anni dall'esordio; f) stabile marcato innalzamento dei valori serici di CK e degli altri enzimi muscolari; g) reperto EMG di danno miopatico primitivo con presenza di fibrillazione a riposo; h) quadro bioptico di miopatia distrofica con atrofia prevalente delle fibre di tipo 2.A nostro parere questa sindrome è una entità nosografica diversa dalle due forme codificate di miopatia distale autosomica recessiva.