Limb-girdle muscular dystrophy subtypes First-reported cohort from northeastern China

The relative frequencies of different subtypes of limb-girdle muscular dystrophies vary widely among different populations. We estimated the percentage of limb-girdle muscular dystrophy subtypes in Chinese people based on 68 patients with limb-girdle muscular dystrophy from the Myology Clinic, Neurology Department, First Hospital of Jilin University, China. A diagnosis of calpainopathy was made in 12 cases （17%）, and dysferlin deficiency in 10 cases （15%）. Two biopsies revealed α-sarcoglycan deficiency （3%）, and two others revealed a lack of caveolin-3 （3%）. A diagnosis of unclassified limb-girdle muscular dystrophy was made in the remaining patients （62%）. The ap-pearances of calpain 3- and dysferlin-deficient biopsies were similar, though rimmed vacuoles were unique to dysferlinopathy, while inflammatory infiltrates were present in both these limb-girdle muscular dystrophy type 2D biopsies. Macrophages were detected in seven dysferlinopathy biop-sies. The results of this study suggest that the distribution of limb-girdle muscular dystrophy sub-types in the Han Chinese population is similar to that reported in the West. The less necrotic, re-generating and inflammatory appearance of limb-girdle muscular dystrophy type 2A, but with more lobulated fibers, supports the idea that calpainopathy is a less active, but more chronic disease than dysferlinopathy. Unusual features indicated an extended limb-girdle muscular dystrophy disease spectrum. The use of acid phosphatase stain should be considered in suspected dysferlinopathies. To the best of our knowledge, this is the first report to define the relative proportions of the various forms of limb-girdle muscular dystrophy in China, based on protein testing.

R25G mutation in exon 1 of LMNA gene is associated with dilated cardiomyopathy and limb-girdle muscular dystrophy 1B

Background Mutations of the LMNA gene encoding lamin A and C are associated with dilated cardiomyopathy （DCM）, conduction system defects and skeletal muscle dystrophy. Here we report a family with a mutation of the LMNA gene to identify the relationship between genotype and phenotype. Methods All 30 members of the family underwent clinical and genetic evaluation. A mutation analysis of the LMNA gene was performed. All of the 12 exons of LMNA gene were extended with polymerase chain reaction （PCR） and the PCR products were screened for gene mutation by direct sequencing. Results Ten members of the family had limb-girdle muscular dystrophy （LGMD） and 6 are still alive. Two patients suffered from DCM. Cardiac arrhythmias included atrioventricular block and atrial fibrillation; sudden death occurred in 2 patients. The pattern of inheritance was autosomal dominant. Mutation c.73C〉G （R25G） in exon 1 encoding the globular domains was confirmed in all of the affected members, resulting in the conversion of arginine （Arg） to glycine （Gly）. Conclusions The mutation R25G in exon 1 of LMNA gene we reported here in a Chinese family had a phenotype of malignant arrhythmia and mild LGMD, suggesting that patients with familial DCM, conduction system defects and skeletal muscle dystrophy should be screened by genetic testing for the LMNA gene.

Muscle Magnetic Resonance Imaging in Patients with Various Clinical Subtypes of LMNA-Related Muscular Dystrophy

Background： LMNA-related muscular dystrophy can manifest in a wide variety of disorders, including Emery-Dreifuss muscular dystrophy （EDMD）, limb-girdle muscular dystrophy （LGMD）, and LMNA-associated congenital muscular dystrophy （L-CMD）. Muscle magnetic resonance imaging （MRI） has become a useful tool in the diagnostic workup of patients with muscle dystrophies. This study aimed to investigate whether there is a consistent pattern of MRl changes in patients with LMNA mutations in various muscle subtypes. Methods： Twenty-two patients with LMNA-related muscular dystrophies were enrolled in this study. M RI of the thigh and/or calf muscles was performed in them. The muscle MRI features of the three subtypes were compared by the Mann-Whitney U-test. The relationship between the clinical and MRI findings was also investigated by Spearman＇s rank analyses. Results： The present study included five EDMD, nine LGMD, and eight L-CMD patients. The thigh muscle MRI revealed that the fatty infiltration of the adductor magnus, semimembranosus, long and short heads of the biceps femoris, and vasti lnuscles, with relative sparing of the rectus femoris, was the predominant change observed in the EDMD, LGMD, and advanced-stage L-CMD phenotypes, ahhough the involvement of the vasti muscles was not prominent in the early stage of L-CMD. At the level of the call; six patients （one EDMD, four LGMD, and one L-CMD） also showed a similar pattern, in which the soleus and the medial and lateral gastrocnemius muscles were most frequently observed to have fatty infiltration. The fatty infiltration severity demonstrated higher scores associated with disease progression. with a corresponding rate of 1.483 ＋ 0.075 × disease dnration （X） （r = 0.444, P - 0.026）. It was noteworthy that in six L-CMD patients with massive inflammatory cell infiltration in muscle pathology, no remarkable edema-like signals were observed in muscle MRI. Conclusions： EDMD, LGMD and advanced-staged L-CMD subtypes showed similar pattern of muscle MRI changes, while early-staged L-CMD showed somewhat different changes. Muscle MRI of L-CMD with a nluscular dystrophy pattern in MRI provided important clues for differentiating it from childhood inflammatory myopathy. The fatty infiltration score could be used as a reliable biomarker for outcome measure of disease progression.