Urinary titin as a biomarker in Fukuyama congenital muscular dystrophy.

Fukuyama congenital muscular dystrophy (FCMD) is the second most prevalent childhood-onset muscular dystrophy in Japan. It is an autosomal recessive disorder caused by the fukutin mutation (FKTN), characterized by muscle wasting and brain abnormalities. So far, serum creatine kinase (CK) is recognized as the only biomarker for FCMD. Recently, an ELISA assay to quantify the N-terminal fragment of titin in urine was developed. Urinary titin concentration is elevated in patients with Duchenne muscular dystrophy (DMD) compared to normal controls. Levels vary according to age with excellent sensitivity and specificity for detecting DMD, and they can be used as a diagnostic and disease progression marker. In this study, we measured the urinary titin concentration of 18 patients with FCMD. It was remarkably higher than normal controls and correlated with CK. Especially in homozygotes, the score for gross motor function measure, which is a quantitative motor scale for FCMD, was correlated with urinary titin concentration. Elevated urinary titin concentrations were thought to be reflective of a common pathophysiology with DMD. Urinary titin concentrations can assist with making the diagnosis of FCMD and to estimate the patient's motor function at that point.

Efficacy of steroid therapy for Fukuyama congenital muscular dystrophy.

Although there is only symptomatic treatment for Fukuyama congenital muscular dystrophy (FCMD), several reports have suggested that steroid therapy could be effective for FCMD; however, no independent intervention studies have been conducted. This study aimed to evaluate the efficacy of steroid therapy for restoring motor functions in FCMD patients. This study involved 3-to-10-year-old FCMD patients who exhibited a decline in motor functions, requested steroid therapy. Patients with consent started oral administration of 0.5-mg/kg prednisolone every alternate day, which was increased to 1.0 mg/kg if the response was inadequate. We used the Gross Motor Function Measure (GMFM) to evaluate and compare the motor functions of all patients. Wilcoxon signed-rank test (significance level, P ≤ 0.05) was used for statistical analysis. At the onset of steroid therapy, 8.10 years (SD, 2.14 years) was the mean age of FCMD patients. The mean GMFM difference between before and after the steroid therapy was + 1.23 (SD, 1.10), and a P value of 0.015 represented significant improvement in GMFM. Our results indicate that steroid therapy may contribute to the maintenance and improvement of the motor functions of advanced-stage FCMD patients.Clinical Trial Registration Registration Number: UMIN000020715, Registration Date: Feb 1st, 2016 (01/02/2016).

High-density areas on muscle CT in childhood-onset Pompe disease are caused by excess calcium accumulation.

We report two patients with childhood-onset Pompe disease showing striking changes with high-density areas on skeletal muscle CT, not seen in adult- or infantile-onset forms of this disease. While the anterior compartment of the thigh muscles was less affected in the adult-onset form, the rectus femoris and tibial muscles were preferentially involved from the early stage in the childhood-onset form of Pompe disease. The high-density areas became increasingly diffuse with disease progression, producing a marbled pattern and ultimately resulting in homogeneous high density and muscle atrophy. Muscle biopsy specimens from the high-density areas showed striking vacuolar changes with many dense globular bodies in lysosomes. High calcium signals were identified by X-ray microanalysis using energy-dispersive X-ray spectroscopy in these areas. Excess calcium accumulation in the vacuoles was also confirmed with the glyoxal-bis(2-hydroxyanil) (GBHA) staining. The high density on CT was slightly reduced together with clinical improvement after enzyme replacement therapy in patient 2. Our data demonstrate that in childhood-onset Pompe disease, high-density areas on skeletal muscle CT images are due to the accumulation of calcium in dense globular bodies formed by a chronic degenerative process affecting autophagic vacuoles.

A short form of gross motor function measure for Fukuyama congenital muscular dystrophy.

OBJECTIVES: The objective of this study was to confirm the validity of a short form of gross motor function measure for Fukuyama congenital muscular dystrophy (GMFM for FCMD). METHODS: This study is a case series and was conducted at the Tokyo Women's Medical University. Fifteen patients with FCMD were assessed using both the GMFM for FCMD with 68 items, which was created as a motor function measure for patients with FCMD on the basis of Rasch analysis, and the original GMFM with 88 items. The correlation between the GMFM for FCMD and the Ueda classification was assessed. Time required for each assessment was also evaluated. RESULTS: We found significant correlation between the GMFM for FCMD and the Ueda classification (r = 0.935); furthermore, the mean assessment time tended to decrease when using the GMFM for FCMD. CONCLUSIONS: GMFM for FCMD may be an appropriate motor function scale for patients with FCMD and might help decrease the assessment time.

[Treatment approach to congenital myasthenic syndrome in a patient with acetylcholine receptor deficiency].

Congenital myasthenic syndromes (CMS) are rare heterogeneous disorders of neurotransmission caused by genetic defects of neuromuscular junction molecules. While CMS patients have been reported worldwide, in Japan there have been only a few descriptions of adult CMS patients with acetylcholinesterase (AChE) deficiency and slow channel syndrome. Herein, we report a Japanese CMS patient with acetylcholine receptor (AChR) deficiency, diagnosed during childhood, and our treatment approach to the patient. This 13-year-old Japanese boy had had severe myasthenic symptoms since infancy. Ptosis, his first symptom, appeared at 5 months and nasal voice was recognized at 2 years of age. AchR and anti-muscle-specific tyrosine kinase (Musk) antibody remained negative. A positive tensilon test and decremental response on electromyogram supported the diagnosis of sero-negative myasthenia gravis. Despite thymectomy and strong immunosuppressive therapy including steroid pulse and FK 506, he gradually deteriorated and became wheelchair bound. Genetic analyses for AchR, Rapsyn, Musk and AChE were negative. At age 11 years, a muscle biopsy was performed in the deltoid muscle for neuromuscular junction sampling. Electron microscopic and confocal microscopic analysis of endplates showed almost complete loss of AChR and the diagnosis of CMS with AChR deficiency was confirmed. All immunosuppressive therapies were discontinued. Instead, we started Ubretide and 3,4-diaminopyridine (DAP) after obtaining informed consent. Although not approved in Japan for this use, 3,4-DAP is reportedly effective in refractory cases of CMS. The patient experienced no side effects. Despite all of the objective data were improving, his subjective symptoms and ADL remained poor. There are still many challenges in the treatment of the patient.

Automatic calculation of Mercuri grades from CT and MR muscle images.

BACKGROUND: Mercuri grading of muscle images is a useful method to evaluate the progression of muscular dystrophies. However, because Mercuri grading is skill-based, few competent experts are available. We therefore developed an automated method for Mercuri grade calculations. METHODS: We used computed tomography (CT) and magnetic resonance (MR) images of the thigh and lower leg muscles taken from a Japanese limb-girdle muscular dystrophy patient database. We calculated muscle impairment ratios based on the CT images, and then converted the ratios to revised Mercuri grades. This method was also applied to T1-weighted MR images. Additionally, radiation absorption doses in muscle and chest CT images from a separate patient group were also analyzed. RESULTS: We observed a close correlation between our automatically calculated Mercuri grades and skill-based visually determined Mercuri grades in both CT and MR images. The radiation absorption, measured by total dose length product, was lower in muscle CT (121.8 mGy-cm) than in chest CT (524.1 mGy-cm). CONCLUSIONS: We developed a new automatic Mercuri grading method using values obtained from CT images. This method was also applied to calculate the Mercuri grade of T1-weighted MR images. In addition, the radiation doses from muscle CT were observed to be lower than those from chest CT.

Assessment of muscle involvement in patients with Duchenne muscular dystrophy via segmental multifrequency bioelectrical analysis.

We investigated the usefulness of segmental multifrequency bioelectrical impedance analyses (MBIA) for assessing muscle involvement in Duchenne muscular dystrophy (DMD) patients. Bioelectrical impedance data of the upper arm, thigh, and lower leg were obtained from 29 boys with DMD (ages 2-17 years old; mean 10.8 ±â€¯3.9 years) at three institutions along with 41 healthy controls (ages 3-16; mean 9.8 ±â€¯3.5 years). Then the muscle density index (MDI: 1- Z250/Z5) was calculated using segmental MBIA and compared between groups. The MDI was lower in boys with DMD, relative to controls, with older DMD patients exhibiting a significant decrease in MDI. The MDI of patient thighs was significantly correlated with the percent muscle volume index (%MVI), as measured using computed tomography (r = 0.79). MDI values for the upper arm, thigh, and lower leg were all significantly correlated with the Brooke and the Vignos scales, respectively, with correlation coefficients of 0.56-0.77. Finally, MDI was significantly greater in the glucocorticoid-treated group, relative to the untreated group in all regions. Taken together, these data show that segmental MBIA is feasible for evaluating muscle involvement and might serve as an outcome measure in DMD.

Renal dysfunction is rare in Fukuyama congenital muscular dystrophy.

BACKGROUND: The leading cause of death in patients with Fukuyama congenital muscular dystrophy (FCMD) is congestive heart failure or respiratory dysfunction, which is same as that in Duchenne muscular dystrophy (DMD). Recent studies reported that renal dysfunction is a common complication and an increasing cause of death in advanced DMD. It can be attributable to circulatory instability or inappropriate use of drugs for treating cardiac dysfunction. METHODS: We retrospectively evaluated renal function in 38 genetically diagnosed patients with FCMD (range, 1.3-32.9 years; mean age, 13.7 ±â€¯6.9 years) using cystatin C. We examined possible relationships of cystatin C with blood natriuretic peptide and creatinine levels along with cardiac echocardiography findings. RESULTS: Twenty-five patients were treated for cardiac dysfunction. Elevated cystatin C level was detected only in two, who also showed proteinuria, glycosuria, hematuria, and extremely high ß2-microglobulin levels on urine tests, and were thus diagnosed with renal tubular cell damage. Because both patients were treated for intractable epilepsy with various antiepileptic drugs, including valproic acid (VPA), and had low serum carnitine levels, renal tubular cell damage was considered as an adverse effect of VPA. Unlike patients with DMD, no patient with FCMD had renal dysfunction. Such a rare occurrence of renal dysfunction can be attributable to mild cardiac dysfunction, short disease duration, and careful and early fluid management. CONCLUSION: Renal dysfunction is rare in patients with FCMD; however, renal tubular cell damage should be ascertained, particularly in those undergoing VPA treatment for epilepsy.

Exon skipping for Duchenne muscular dystrophy: a systematic review and meta-analysis.

BACKGROUND: Exon skipping has been considered a promising therapeutic approach for Duchenne muscular dystrophy (DMD). Eteplirsen received conditional approval in the United States in 2016. To date, no systematic reviews or meta-analyses of randomized controlled trials (RCTs) of exon skipping drugs have been published to determine the pooled estimates for the effect of exon skipping in treating DMD. METHODS: A systematic review and meta-analysis of double-blind RCTs comparing exon-skipping drugs with placebo in DMD was performed. Trials were identified by searching published and unpublished studies from electronically available databases and clinical trial registries through October 2017. The primary outcomes were changes in the 6-min walk test (6MWT) distance, North Star Ambulatory Assessment (NSAA) scores, and adverse events. Random-effects meta-analysis and assessment of risk of bias were performed. This systematic review was registered at PROSPERO (CRD42016037504). RESULTS: Five studies involving 322 participants were included, investigating eteplirsen in one and drisapersen in four studies. There were no changes in 6MWT distance (mean difference [MD] - 9.16, 95% confidence interval [CI] - 21.94 to 3.62) or NSAA scores (MD 1.20, 95% CI - 2.35 to 4.75) after 24 weeks of treatment in the exon-skipping group compared with placebo. Subgroup analysis for a 6 mg/kg weekly injection of drisapersen showed significant changes in the 6MWT, favoring drisapersen after 24 weeks (MD - 20.24; 95% CI - 39.59 to - 0.89). However, drisapersen resulted in a significant increase in injection site reactions (risk ratio [RR] 3.67, 95% CI 1.96 to 6.89, p < 0.0001) and renal toxicity (RR 1.81, 95% CI 1.11 to 2.94, p = 0.02). Risk of bias was high in two of the five studies, including the eteplirsen and one drisapersen study. CONCLUSIONS: Current available data do not show evidence that exon-skipping drugs are effective in DMD. Despite potential effectiveness when used at a specific dose, significant side effects were reported with drisapersen. The small number of RCTs with relatively small numbers of participants indicate the difficulty in conducting sufficiently powered studies of DMD. Prospectively planned meta-analysis and utilization of the real-world data may provide a more precise estimate of the effect of exon skipping in this disease.

National registry of patients with Fukuyama congenital muscular dystrophy in Japan.

Fukuyama congenital muscular dystrophy (FCMD) is the second most common form of muscular dystrophy in the Japanese population and is caused by mutations in the fukutin (FKTN) gene. In 2011, the Japan Muscular Dystrophy Association (JMDA) developed a nationwide registry of genetically confirmed patients with FCMD. We retrospectively reviewed the registry dataset of patients with FCMD to obtain data, including age, sex, developmental milestones, intellectual level, complications, and primary treatments. In total, 207 patients with FCMD (104 boys and 103 girls) were registered by the end of September 2013. Mean patient age at first registration was 8.1 ±â€¯7.8 years (median, 6 years; range, 0-42 years). A homozygous 3-kb founder insertion mutation in the FKTN gene was present in 80% of registrants, whereas 20% had a compound heterozygous mutation. Sixty-nine patients (33%) had febrile seizures and/or epilepsy. Myopia was the most frequently detected abnormality (8.7%), followed by strabismus (5.9%). Overall, 16% of patients required respiratory support and this percentage increased with age. Cardiac dysfunction was detected in 16%, and dysphagia was observed in 22% of patients with FCMD. The FCMD patient registry is useful for clarifying the natural history of FCMD and recruiting patients for clinical trials.

Characteristic findings of skeletal muscle MRI in caveolinopathies.

Caveolinopathies, caused by CAV3 mutations, can include several phenotypes such as rippling muscle disease, limb-girdle muscular dystrophy type 1C, distal myopathy, familial hypertrophic cardiomyopathy, and idiopathic hyperCKemia. Here we present characteristic skeletal muscle imaging findings in four patients with genetically defined childhood-onset RMD caused by CAV3 mutations and in one patient with congenital generalized lipodystrophy type 4 with muscular dystrophy due to polymerase I and transcript release factor (PTRF) mutations, which may have caused secondary deficiency of caveolin-3. Muscle MRI revealed that the rectus femoris and semitendinosus muscles were most commonly affected in the rippling muscle disease patients. Peripheral changes in the rectus femoris were specific and observed even in one of the younger patients in this study. Furthermore, muscle involvement extended to the semitendinosus muscles, biceps femoris, and gracilis with disease progression or increase in its severity. Similar patterns of involvement were observed on reviewing skeletal muscle images of various previously reported phenotypes of caveolinopathy; interestingly, patients with secondary deficiency of caveolin due to PTRF mutations revealed the same pattern. Thus, primary caveolinopathies and secondary deficiency of caveolin demonstrated specific findings on skeletal muscle imaging, regardless of the broad phenotypic spectrum of these two conditions.

Limb-girdle muscular dystrophy due to emerin gene mutations.

BACKGROUND: Emery-Dreifuss muscular dystrophy, caused by EMD gene mutations, is characterized by humeroperoneal muscular dystrophy, joint contractures, and conduction defects and is often associated with sudden cardiac death, even without prior cardiac symptoms. OBJECTIVE: To describe the clinical and molecular features of 2 patients with limb-girdle muscular dystrophy with mutations in EMD. DESIGN: Case reports. SETTING: Academic research. PATIENTS: Two male patients manifested proximal dominant muscle involvement, with minimal or no joint and cardiac involvement. MAIN OUTCOME MEASURES: Muscle biopsy and mutation analysis results. RESULTS: Immunohistochemistry revealed an absence of emerin staining in muscle biopsy specimens. Mutation analysis identified nonsense mutations in EMD. CONCLUSIONS: Mutations in EMD may indicate a limb-girdle muscular dystrophy phenotype. Identification of emerin deficiency among patients with limb-girdle muscular dystrophy is essential to prevent cardiac catastrophe.

A novel FKRP gene mutation in a Taiwanese patient with limb-girdle muscular dystrophy 2I.

Limb-girdle muscular dystrophy (LGMD) is a group of hereditary muscle diseases with preferential involvement of the shoulder and pelvic girdle muscles, but with no pathognomonic features as in facioscapulohumeral and congenital muscular dystrophies. We report 18-year-old female with progressive shoulder and pelvic muscle weakness. She had marked restrictive pulmonary dysfunction. Echocardiogram showed mild decrease in ejection fraction of 52% (normal: >55%). She was first seen in our hospital at age 2 years with progressive proximal muscle weakness and elevated creatine kinase (CK) level to 15,290 IU/L, with what clinically and pathologically appeared to be steroid-responsive inflammatory myopathy. She responded dramatically to steroid therapy. Progressive proximal muscle weakness began again at age 8 years. Serum CK was 14,910 IU/L. She was wheelchair-bound by age 12. Muscle biopsy showed dystrophic changes without inflammation with reduced immunoreactivity to an antibody against sugar chain (VIA4-1) of alpha-dystroglycan. On laminin overlay assay, there was a nearly complete loss of laminin-binding activity to alpha-dystroglycan. Genetic analysis of fukutin-related protein (FKRP) gene revealed a novel compound heterozygous mutation of c.823C>T (p.R275C) and c.948delC, confirming the diagnosis of LGMD2I, the first reported case in East Asia.

The gross motor function measure is valid for Fukuyama congenital muscular dystrophy.

Fukuyama congenital muscular dystrophy (FCMD) is the second most common muscular dystrophy in Japan. FCMD is an autosomal recessive disorder caused by mutations in the fukutin gene. The main features of FCMD are a combination of infantile-onset hypotonia, generalized muscle weakness, eye abnormalities, and mental retardation associated with cortical migration defects, and most patients are never able to walk. To date, the development of a quantitative motor scale for FMCD has been difficult due to the moderate-to-severe intellectual impairment that accompanies FCMD. Gross motor function measure (GMFM), originally developed as a quantitative motor scale for cerebral palsy, can precisely and quantitatively assess motor function without complicated instructions, and was recently reported to be useful in the assessment of Down syndrome and spinal muscular atrophy. To confirm the validity of GMFM for the assessment of FCMD, 41 FCMD patients (age range: 0.6-24.4 years) were recruited for this study. The GMFM scores correlated significantly with those of two previously used motor scales, and the time-dependent change in GMFM scores was consistent with the natural course of FCMD. The inter-rater reliability, based on determinations made by four physiotherapists blinded to each other's assessment results, was excellent. We concluded GMFM to be a useful and valid measure of motor function in FCMD patients.

A case of Fukuyama-type congenital muscular dystrophy with a very mild mental deficit.

A boy had the clinical features of congenital muscular dystrophy with a very mild mental deficit. A muscle biopsy at one year of age showed the typical findings of Fukuyama-type congenital muscular dystrophy, including selective loss of immunoreactions for alpha dystroglycan. Magnetic resonance imaging showed no findings suggestive of migration disorders. The diagnosis of Fukuyama-type congenital muscular dystrophy was confirmed by a molecular assay at 8 years of age, and his haplotype analysis was heterozygous. At 9 years of age, his FIQ on the Wechsler Scale for Children revealed 69, while his IQ on the Tanaka Binnet scale of intelligence was 97. In this report the relationship between mild clinical condition of the studied case and its genotype is discussed.

Respiratory management of patients with Fukuyama congenital muscular dystrophy.

BACKGROUND: Fukuyama congenital muscular dystrophy (FCMD), characterized by intellectual impairment associated with cortical migration defects, is an autosomal recessive disorder caused by mutation in the fukutin gene. It is the second most common type of muscular dystrophy in Japan. Respiratory dysfunction, along with cardiomyopathy, can be life-threatening in patients with advanced-stage FCMD. However, few reports have focused on this issue. METHODS: We retrospectively studied respiratory dysfunction and therapeutic management in 48 genetically diagnosed FCMD patients (mean age 11.0 years; range 3.6-31.9 years). RESULTS: Mechanical ventilation was initiated at a median age of 12.1 years in 16 patients, 14 of whom received non-invasive positive pressure ventilation (NPPV) while the other 2 underwent tracheostomy with invasive ventilation (TIV). The two TIV cases had unexpectedly required the initiation of ventilatory support at the ages of 15.7 and 18.0 years, respectively, because of unsuccessful extubation followed by serious respiratory infections, despite rather good respiratory function before these episodes. Patients carrying a compound heterozygous founder mutation or with a severe phenotype tended to need ventilatory support 2-3 years earlier than homozygous patients and those with the typical or mild phenotype. Mechanical insufflation-exsufflation (MI-E) interventions were also employed in six patients with serious dysphagia and were well-tolerated in all cases. CONCLUSION: For respiratory management, it is important to regularly evaluate respiratory function in FCMD patients over 10 years of age, since intellectual impairment and insomnia often mask the signs of respiratory dysfunction. Most patients, despite poor cooperation due to intellectual impairment, can tolerate NPPV and MI-E provided that a carefully worked-out plan is adopted.

Congenital muscular dystrophy with glycosylation defects of alpha-dystroglycan in Japan.

Glycosylation defects of alpha-dystroglycan (alpha-DG) cause various muscular dystrophies. We performed clinical, pathological and genetic analyses of 62 Japanese patients with congenital muscular dystrophy, whose skeletal muscle showed deficiency of glycosylated form of alpha-DG. We found, the first Japanese patient with congenital muscular dystrophy 1C with a novel compound heterozygous mutation in the fukutin-related protein gene. Fukuyama-type congenital muscular dystrophy was genetically confirmed in 54 of 62 patients. Two patients with muscle-eye-brain disease and one Walker-Warburg syndrome were also genetically confirmed. Four patients had no mutation in any known genes associated with glycosylation of alpha-DG. Interestingly, the molecular mass of alpha-DG in the skeletal muscle was similar and was reduced to approximately 90 kDa among these patients, even though the causative gene and the clinico-pathological severity were different. This result suggests that other factors can modify clinical features of the patients with glycosylation defects of alpha-DG.

Close monitoring of initial enzyme replacement therapy in a patient with childhood-onset Pompe disease.

Pompe disease is classified into infantile and late-onset (childhood and adult) forms based on onset age and degree of organ involvement. While benefits of enzyme replacement therapy (ERT) for the infantile form have been confirmed, efficacy for late-onset forms reportedly varies. We report close monitoring of initial ERT, focusing especially on the first year, in a 12-year-old boy with childhood-onset Pompe disease. At age 10, he started ERT at 20 mg/kg every other week. Respiratory and motor functions were evaluated at each infusion, and by skeletal muscle computed tomography (CT) and cardiac echography every 4 months. He gained the ability to climb stairs without a rail and % vital capacity improved just 1.5 months after starting ERT. Grip power, manual muscle testing (MMT) and the timed and 6-min walking distance tests (6MWT) improved promptly, paralleling improvements in clinical symptoms. However, this steady improvement stopped around 8 months, with deterioration to the initial level by about 24 months. Antibody against recombinant human alpha-glucosidase was very low at 15 months; therefore, the lack of treatment response did not completely correspond to antibody production. On the other hand, cardiac wall thickening worsened after 4 months, then improved to better than baseline after 8 months, and this improvement was well maintained. Among our set parameters, the timed test results corresponded better to his changing clinical course than did grip power, MMT or 6-min walking test results.

Severe muscle damage following viral infection in patients with Fukuyama congenital muscular dystrophy.

Fukuyama congenital muscular dystrophy (FCMD), which is characterized by cortical migration defect and eye abnormalities, is the most common subtype of CMD in Japan. Fukutin (FKTN), the responsible gene for FCMD, encodes a protein involved in the glycosylation of alpha-dystroglycan. We have experienced some patients with FCMD who showed sudden exacerbation of muscle weakness with marked elevation of serum creatine kinase (CK) and urinary myoglobin levels a few days after a febrile episode of viral infection, occasionally leading to death. To describe this peculiar phenomenon, we focused on 12 patients who developed a sudden exacerbation of muscle weakness among 96 genetically defined FCMD patients and hospitalized because of a febrile illness at Tokyo Women's Medical University between 1997 and 2008. All the 12 patients were homozygous for a 3-kb insertion mutation of FKTN. The patients developed exacerbation of muscle weakness ranging from paralysis to loss of head control. The onset was concentrated in summer, and coxsackieviruses and enteroviruses were most often detected, especially in infantile patients. Eight of the 12 patients were treated with corticosteroids and recovered within 2 weeks. Four patients were treated without steroid, and needed 18.5 days on mean for improvement. None developed renal failure. The reason for muscle damage induced by viral infection remains unknown; however, physicians should consider its risk, sometimes leading to death, and draw it to parents' attention, especially in the defervescent stage.