Katsuhito Adachi

Cardiac dysfunction with Becker muscular dystrophy

Cardiac function was examined in 21 patients with Becker muscular dystrophy (BMD) and compared with 43 patients with Duchenne muscular dystrophy (DMD) and 37 healthy control subjects. Electrocardiography showed myocardial damage was most frequently found in the lateral wall, compatible with autopsy findings. The ratio of the preejection period to the ejection time was higher in patients with BMD (0.37 +/- 0.07, mean +/- SD) than in patients with DMD (0.28 +/- 0.05) and healthy controls (0.23 +/- 0.04). Left ventricular dimension and mitral annular size at end diastole in patients with BMD increased to 52.3 +/- 7.7 mm and 28.8 +/- 5.3 mm with age, respectively. In patients with cardiac failure and BMD, mitral regurgitation was observed at a rate of 66.7%. No definite relation between the deleted locus of the dystrophin gene and cardiac failure was found. Because motor dysfunction progresses more slowly in BMD than in DMD, a prolonged work load on the morbid myocardium may lead to dilated cardiomyopathy with mitral regurgitation.

Adhalin gene mutations in patients with autosomal recessive childhood onset muscular dystrophy with adhalin deficiency.

Homozygous adhalin gene mutations were found in three patients from two consanguineous families with autosomal recessive childhood onset muscular dystrophy. Muscle biopsies from patients in each family showed complete absence of adhalin. Sequencing of adhalin cDNA prepared from skeletal muscle by reverse transcription PCR demonstrated a cytosine to thymidine substitution at nt 229 in the patient in family 1 and an adenine to guanine substitution at nt 410 and a 15-base insertion between nt 408 and 409 in the two patients in family 2. Sequencing of genomic DNA prepared from peripheral blood leukocytes by PCR confirmed these mutations. The parents in each family were found to be heterozygous for the respective mutations. These adhalin gene mutations are presumed to be responsible for the absence of adhalin in the skeletal muscle. Adhalin deficiency likely causes disruption of the muscle cell membrane, resulting in dystrophic changes in the skeletal muscle similar to dystrophin deficiency in Duchenne muscular dystrophy.

Proteolysis of β-dystroglycan in muscular diseases

Alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix (ECM), while beta-dystroglycan is a type I integral membrane protein which anchors alpha-dystroglycan to the cell membrane via the N-terminal extracellular domain. The complex composed of alpha-and beta-dystroglycan is called the dystroglycan complex. We reported previously a matrix metalloproteinase (MMP) activity that disrupts the dystroglycan complex by cleaving the extracellular domain of beta-dystroglycan. This MMP creates a characteristic 30 kDa fragment of beta-dystroglycan that is detected by the monoclonal antibody 43DAG/8D5 directed against the C-terminus of beta-dystroglycan. We also reported that the 30 kDa fragment of beta-dystroglycan was increased in the skeletal and cardiac muscles of cardiomyopathic hamsters, the model animals of sarcoglycanopathy, and that this resulted in the disruption of the link between the ECM and cell membrane via the dystroglycan complex. In this study, we investigated the proteolysis of beta-dystroglycan in the biopsied skeletal muscles of various human muscular diseases, including sarcoglycanopathy, Duchenne muscular dystrophy (DMD), Becker muscular dystrophy, Fukuyama congenital muscular dystrophy, Miyoshi myopathy, LGMD2A, facioscapulohumeral muscular dystrophy, myotonic dystrophy and dermatomyositis/polymyositis. We show that the 30 kDa fragment of beta-dystroglycan is increased significantly in sarcoglycanopathy and DMD, but not in the other diseases. We propose that the proteolysis of beta-dystroglycan may contribute to skeletal muscle degeneration by disrupting the link between the ECM and cell membrane in sarcoglycanopathy and DMD.

Clinical, pathological, and genetic features of limb‐girdle muscular dystrophy type 2A with new calpain 3 gene mutations in seven patients from three Japanese families

We report on the clinical, pathological, and genetic features of 7 patients with limb‐girdle muscular dystrophy type 2A (LGMD2A) from three Japanese families. The mean age of onset was 9.7 ± 3.1 years (mean ± SD), and loss of ambulance occurred at 38.5 ± 2.1 years. Muscle atrophy was predominant in the pelvic and shoulder girdles, and proximal limb muscles. Muscle pathology revealed dystrophic changes. In two families, an identical G to C mutation at position 1080 the in calpain 3 gene was identified, and a frameshift mutation (1796insA) was found in the third family. The former mutation results in a W360R substitution in the proteolytic site of calpain 3, and the latter in a deletion of the Ca2+‐binding domain.

Decrease in urinary excretion of 3-methylhistidine by patients with Duchenne muscular dystrophy during glucocorticoid treatment.

Seven patients, aged 10–17 years, with Duchenne muscular dystrophy were treated orally with prednisolone (PSL) at a dose of 0.8–1.0 mg/kg per day for 8 weeks. During the treatment their muscle strength, serum creatine kinase (CK) activity, serum levels of myoglobin (Mb), and urinary excretion of 3-methyl-histidine (3-MeH) and glycine (Gly) were measured serially. In all the patients, the motor function or muscle strength improved, and the serum CK activity and Mb level decreased during PSL treatment. Urinary excretion of 3-MeH, a unique constituent of muscle contractile proteins, decreased to 51–63% of the baseline value in weeks 6–9 after the start of PSL administration, and returned to the baseline level in week 12. The ratios of 3-MeH to creatinine and to Gly also decreased during the treatment. Urinary excretion of Gly, which is ubiquitous in all tissues including muscle, did not decrease during the treatment. These findings suggest that PSL inhibits proteolysis of muscle contractile protein.

Different manners of sarcoglycan expression in genetically proven α-sarcoglycan deficiency and γ-sarcoglycan deficiency

Abstract We investigated the expression of α-sarcoglycan, β-sarcoglycan, γ-sarcoglycan, and δ-sarcoglycan immunohistochemically in three patients with mutations of the α-sarcoglycan gene and a patient with a mutation of the γ-sarcoglycan gene. Although each of the four sarcoglycans were decreased on the muscle membranes of all the patients, different expression patterns for each were seen among the patients. In patients with mutations of the α-sarcoglycan gene, β-, γ- and δ-sarcoglycans were relatively preserved as compared to greatly reduced α-sarcoglycan. However, the patient with a mutation of the γ-sarcoglycan gene showed marked reduction of γ-sarcoglycan as compared to partially preserved α- and β-sarcoglycans, and well-preserved δ-sarcoglycan. These results suggest that each sarcoglycan component in sarcoglycanopathy does not decrease in the same manner, and that mutations of the sarcoglycan gene can be predicted, at least in part, by means of sensitive immunohistochemistry for each sarcoglycan.

Diagnostic utility of cardiac magnetic resonance for detection of cardiac involvement in female carriers of Duchenne muscular dystrophy

Background Cardiac involvement is a recognised complication in female carriers of Duchenne muscular dystrophy (DMD). Since segmental or global left ventricle (LV) wall motion abnormalities in DMD carriers can arise even without apparent muscle weakness, it is difficult to differentiate cardiac involvement of a DMD carrier from other heart diseases in a non-invasive manner. Cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) enables assessment of regional wall motion abnormality and myocardial damage with high spatial resolution. Objective To assess the utility of CMR for detection of myocardial damage in female carriers of DMD. Methods and results Gadolinium-enhanced CMR was performed in seven female DMD carriers. Physical examination, electrocardiography, chest radiograph, measurements of total creatinine kinase and brain natriuretic peptide levels, and two-dimensional echocardiography were also performed. Four (57%) of the seven carriers had LGE, and LGE was frequently observed at the subepicardial layer in the inferolateral segment. Two carriers had a focal LGE at the LV inferolateral wall without LV dilation or wall motion abnormalities. Conclusion CMR findings of DMD carriers were characterised by subepicardial LGE, which was localised at inferolateral segments. CMR may be a useful modality for detecting cardiac involvement in DMD carriers.

Detection and management of cardiomyopathy in female dystrophinopathy carriers

Regular health checkups for mothers of patients with Duchenne muscular dystrophy have been performed at National Hospital Organization Tokushima Hospital since 1994. Among 43 mothers participated in this study, 28 dystrophinopathy carriers were identified. Skeletal and cardiac muscle functions of these subjects were examined. High serum creatine kinase was found in 23 subjects (82.1%). Obvious muscle weakness was present in 5 (17.8%) and had progressed from 1994 to 2015. Cardiomyopathy was observed in 15 subjects (60.0%), including dilated cardiomyopathy-like damage that was more common in the left ventricular (LV) posterior wall. Late gadolinium enhancement on cardiac MRI was found in 5 of 6 subjects, suggesting fibrotic cardiac muscle. In speckle tracking echocardiography performed seven years later, global longitudinal strain was decreased in these subjects, indicating LV myocardial contractile abnormality. These results suggest that female dystrophinopathy carriers should receive regular checkups for detection and treatment of cardiomyopathy, even if they have no cardiac symptoms.

Survey on genetic counseling and health management for symptomatic and asymptomatic female dystrophinopathy carriers in Japan today.

To clarify the current status of genetic counseling and health monitoring for symptomatic and asymptomatic female carriers of dystrophinopathy (Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)), we sent out questionnaires to 104 member institutions of The Japans National Liaison Council for Clinical Sections of Medical Genetics, and responses were received from 51 institutions. Between April 2013 and March 2014, 57 carriers at 21 institutions received genetic counseling, and 37 carriers at 15 institutions underwent genetic screening for DMD/BMD mutations. At the 23 institutions that gave genetic counseling, 20 (87%) informed carriers of possible health problems, 14 (61%) informed carriers of cardiomyopathy and heart failure, and 14 (61%) advised carriers about regular medical checkups. Evidence based on accurate and up-to-date epidemiological studies of female carriers is needed and should be widely shared with the families, medical providers, and society.

G.P.12.04 Clinical features, particularly those of the central nervous system of patients with Becker muscular dystrophy, including autopsied cases

There are no detailed reports about the clinical and pathological findings in the central nervous system (CNS) of patients with Becker’s muscular dystrophy (BMD), although dysfunctions of the skeletal and cardiac muscles are well known in BMD. Since dystrophin is present in the CNS, and usual medical treatment is often influenced by CNS manifestations in patients, we studied the clinical and pathological features of BMD, with particular focus on the CNS manifestations, and also examined the relationships of these features with skeletal and cardiac muscle dysfunctions. We examined eight BMD patients aged 24-77 years who were admitted to our hospital, and six autopsied BMD patients aged 39-58 years. In addition to family histories of the patients, clinical findings, and disease progression, BMD was diagnosed based on the presence of dystrophin revealed by immunohistochemical examination and examination of the dystrophin gene. Brain computed tomography (CT), magnetic resonance imaging (MRI), and CNS pathohistology were also performed. Gene analyses by multiplex PCR revealed that exons 3-4, 3-6, 12-19, 45-47,45-49, and 45-52 were deleted; all the deletions occurred in hot spots in the dystrophin gene. With regard to the clinical CNS manifestations of BMD, 2 of the 14 patients experienced hallucinations, but there was no patient with severe mental retardation. Brain CT and MRI scans revealed various grades of mild atrophy of the front-parietal lobe for all the patients. Low-magnification microscopy images of the brain of three autopsied patients with mild BMD showed that the gyri of the brain were separated, suggesting brain atrophy. The nerve cells of the frontal lobe, however, seemed to be unaffected histologically. These results show that there are mild abnormalities in the CNS of BMD patients. It is well known that BMD patients demonstrate different levels of skeletal and cardiac muscle dysfunctions. In the current study as well, the BMD patients demonstrated CNS abnormalities, although these abnormalities were mild compared to the skeletal and cardiac muscle dysfunctions.