OBJECTIVE: To explore the correlation between clinical manifestations of Limb-girdle muscular dystrophy autosomal recessive 9 FKRP-related (R9 FKRP-related) and variants of the FKRP gene. METHODS: Two children who had presented at the Children's Hospital of Nanjing Medical University respectively due to increased serum myocardial zymogram and hepatic dysfunction on September 30, 2018 and August 3, 2018 were selected as the study subjects. Clinical data of the children were collected. Both children were suspected for Duchenne or Becker muscular dystrophy for asymptomatic high creatine kinase (CK) levels. Peripheral blood samples of the children and their parents were collected for whole exome sequencing, and candidate variants were validated by Sanger sequencing. RESULTS: Genetic testing revealed that both children have carried compound heterozygous variants of the FKRP gene. The c.545A>G and c.941C>T variants in child 1 have been reported previously, among which the c.545A>G is a hot spot mutation in the Chinese population. Child 2 has carried c.602T>C and c.961G>A variants, both of which were unreported previously. CONCLUSION Both children have met the diagnostic criteria for LGMD R9 FKRP-related. Carriers of the c.545A>G variant may present milder symptoms. Compared with patients carrying null variants, carriers of compound heterozygous missense variants may present with a milder phenotype, manifesting as asymptomatic high CK level.
Humans ; Child ; Asian People/genetics* ; Genetic Testing ; Muscular Dystrophies, Limb-Girdle/genetics* ; Muscular Dystrophy, Duchenne ; Pentosyltransferases/genetics*

OBJECTIVE: To explore the genetic basis for a neonate featuring developmental delay. METHODS: Clinical examination and laboratory tests were carried out for the patient. Peripheral venous blood samples of the proband and his parents were extracted and subjected to target capture next generation sequencing. Candidate variant was verified by Sanger sequencing. RESULTS: The patient, a four-month-old male, has presented with developmental delay and weakness of limbs. Genetic testing revealed that he had harbored a novel c.1432C>T variant of the TNPO3 gene, which was inherited from his mother. The nonsense variant has resulted in premature termination of protein translation and was predicted to be pathogenic by bioinformatics analysis. CONCLUSION The heterozygous c.1432C>T variant of the TNPO3 gene probably underlay the limb-girdle muscular dystrophies form 1F in this patient. Above finding has enriched the variation spectrum of the TNPO3 gene.
Genetic Testing ; Heterozygote ; High-Throughput Nucleotide Sequencing ; Humans ; Infant ; Male ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation ; Phenotype ; beta Karyopherins/genetics*

OBJECTIVE: To analyze the clinical features and genetic variants of three Chinese pedigrees affected with Limb girdle muscular dystrophy type 2I (LGMD2I). METHODS: Clinical data and peripheral blood samples of the three probands and their family members were collected. Whole exome sequencing was carried out for the probands. Candidate variants were verified by Sanger sequencing of their family members. RESULTS: Probands 1 and 2 both featured weakness in the lower limbs. Proband 1 had lost walking ability and had pulmonary ventilation dysfunction. Proband 3 had lower limb pain, palpitations and asthma after exercise. Genetic sequencing revealed that proband 1 harbored compound heterozygous c.545A>G (p.Y182C) and c.1391A>T (p.N464I) variants of the FKRP gene, proband 2 harbored compound heterozygous c.545A>G (p.Y182C) and c.941C>T (p.T314M) variants of the FKRP gene, and proband 3 harbored compound heterozygous c.545A>G (p.Y182C) and c.161G>A (p.R54Q) variants. Among these, the c.161G>A (p.R54Q) variant was unreported previously. CONCLUSION Compound heterozygous variants of the FKRP gene probably underlay the LGMD2I in the three patients. Whole exome sequencing is crucial for the diagnosis of LGMD2I. The identification of the novel variant also broadened the mutational spectrum of the FKRP gene.
Humans ; Pedigree ; Pentosyltransferases/genetics* ; Muscle, Skeletal ; Proteins/genetics* ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation ; China

OBJECTIVES: To summarize the skeletal muscle magnetic resonance imaging (MRI) features of the lower limbs in common subtypes of muscular dystrophy (MD) and the experience in the application of MRI in the diagnosis of MD. METHODS: A total of 48 children with MD who were diagnosed by genetic testing were enrolled as subjects. The muscle MRI features of the lower limbs were analyzed. Cumulative fatty infiltration score was calculated for each subtype, and the correlation of cumulative fatty infiltration score with clinical indices was analyzed for Duchenne muscular dystrophy (DMD). RESULTS: DMD was characterized by the involvement of the gluteus maximus and the adductor magnus. Becker muscular dystrophy was characterized by the involvement of the vastus lateralis muscle. Limb-girdle muscular dystrophy was characterized by the involvement of the adductor magnus, the vastus intermedius, the vastus medialis, and the vastus lateralis muscle. For DMD, the cumulative fatty infiltration score of the lower limb muscles was significantly correlated with age, course of the disease, muscle strength, and motor function (P<0.05), while it was not significantly correlated with the serum creatine kinase level (P>0.05). CONCLUSIONS Different subtypes of MD have different MRI manifestations, and MRI may help with the diagnosis and assessment of MD.
Child ; Humans ; Muscular Dystrophy, Duchenne/diagnostic imaging* ; Muscular Dystrophies, Limb-Girdle/pathology* ; Muscle, Skeletal/diagnostic imaging* ; Magnetic Resonance Imaging/methods* ; Thigh/pathology*

China ; Dysferlin/genetics* ; Humans ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation

OBJECTIVE: To analyze the clinical phenotype and genetic variants in five Chinese pedigrees affected with Dysferlinopathy. METHODS: Next generation sequencing (NGS) was carried out for the probands from the five pedigrees. Suspected variants were validated by Sanger sequencing. Pathogenicity of the variants was assessed based on the standards and guidelines by the American College of Medical Genetics and Genomics (ACMG). RESULTS: Ten DYSF gene variants (including 5 frameshift variants, 3 splicing variants, 1 missense variant and 1 nonsense variant) were detected. Among these, c.1375dupA (p.Met459Asnfs*15), c.610C>T (p.Arg204X), c.1180+5G>A and c.1284+2T>C were known to be pathogenic, while c.4008_4010delCCTinsAC (p.Leu1337Argfs*8), c.1137_1169del (p.379_390del), c.754A>G(p.Thr252Ala), c.1175_1176insGCAGAGTG (p.Met394Serfs*7), c.3114_3115insCGGC (p.Arg1040Profs*74) and c.1053+3G>C were unreported previously. Of the six novel variants, c.1137_1169del, c.1175_1176insGCAGAGTG and c.3114_3115insCGGC were predicted as pathogenic (PVS1+PM2+PM3), c.4008_4010delCCTinsAC as likely pathogenic (PVS1+PM2), c.754A>G and c.1053+3G>C as variants of uncertain significance based on the ACMG standards and guidelines. CONCLUSION Variants of the DYSF gene probably underlay Dysferlinopathy in the patients among the five pedigrees. Above finding has enriched the spectrum of DYSF gene variants.
Humans ; Muscular Dystrophies, Limb-Girdle/genetics* ; Mutation ; Pedigree ; Phenotype ; RNA Splicing

Heart ; Humans ; Muscular Dystrophies, Limb-Girdle/genetics*

OBJECTIVE: To analyze variant of SGCA gene in a Chinese pedigree affected with limb-girdle muscular dystrophy type 2D with whole exome sequencing (WGS). METHODS: Multiplex ligation-dependent probe amplification (MLPA) was employed to detect large fragment deletion or duplication of the DMD gene. FastTarget next generation sequencing was used to detect variants of the DMD gene, and the result was verified by Sanger sequencing. After excluding the diagnosis of DMD for the proband, WGS was applied to test the proband and his parents. Suspected pathogenic variants were validated by Sanger sequencing. RESULTS: No variant, deletion or duplication of the DMD gene was detected. Whole exome sequencing showed that the proband has carried compound heterozygous missense variants c.409G>A (p.Glu137Lys) and c.409G>C (p.Glu137Gln) in exon 5 of the SGCA gene, which were respectively inherited from his mother and father. Neither variant was found in DNA derived from the cord blood sample. CONCLUSION The c.409G>A (p.Glu137Lys) and c.409G>C (p.Glu137Gln) compound heterozygous missense variants probably underlie the disease in the proband. Above finding has facilitated genetic counseling and prenatal diagnosis for the family.
Exons ; Female ; Humans ; Muscular Dystrophies, Limb-Girdle ; Pedigree ; Pregnancy

Anoctamin 5 (ANO5)/TMEM16E belongs to a member of the ANO/TMEM16 family member of anion channels. However, it is a matter of debate whether ANO5 functions as a genuine plasma membrane chloride channel. It has been recognized that mutations in the ANO5 gene cause many skeletal muscle diseases such as limb girdle muscular dystrophy type 2L (LGMD2L) and Miyoshi muscular dystrophy type 3 (MMD3) in human. However, the molecular mechanisms of the skeletal myopathies caused by ANO5 defects are poorly understood. To understand the role of ANO5 in skeletal muscle development and function, we silenced the ANO5 gene in C2C12 myoblasts and evaluated whether it impairs myogenesis and myotube function. ANO5 knockdown (ANO5-KD) by shRNA resulted in clustered or aggregated nuclei at the body of myotubes without affecting differentiation or myotube formation. Nuclear positioning defect of ANO5-KD myotubes was accompanied with reduced expression of Kif5b protein, a kinesin-related motor protein that controls nuclear transport during myogenesis. ANO5-KD impaired depolarization-induced [Ca²⁺]i transient and reduced sarcoplasmic reticulum (SR) Ca²⁺ storage. ANO5-KD resulted in reduced protein expression of the dihydropyridine receptor (DHPR) and SR Ca²⁺-ATPase subtype 1. In addition, ANO5-KD compromised co-localization between DHPR and ryanodine receptor subtype 1. It is concluded that ANO5-KD causes nuclear positioning defect by reduction of Kif5b expression, and compromises Ca²⁺ signaling by downregulating the expression of DHPR and SERCA proteins.
Active Transport, Cell Nucleus ; Calcium Channels, L-Type ; Cell Membrane ; Chloride Channels ; Humans ; Muscle Development ; Muscle Fibers, Skeletal ; Muscle, Skeletal ; Muscular Diseases ; Muscular Dystrophies ; Muscular Dystrophies, Limb-Girdle ; Myoblasts ; RNA, Small Interfering ; Ryanodine Receptor Calcium Release Channel ; Sarcoplasmic Reticulum

BACKGROUND AND PURPOSE: GNE myopathy is a rare progressive myopathy caused by biallelic mutations in the GNE gene, and frequently accompanied by rimmed vacuoles in muscle pathology. The initial symptom of foot drop or hip-girdle weakness eventually spreads to all limbs over a period of decades. Recent advances in pathophysiologic research have facilitated therapeutic trials aimed at resolving the core biochemical defect. However, there remains unsettled heterogeneity in its natural course, which confounds the analysis of therapeutic outcomes. We performed the first large-scale study of Korean patients with GNE myopathy. METHODS: We gathered the genetic and clinical profiles of 44 Korean patients with genetically confirmed GNE myopathy. The clinical progression was estimated retrospectively based on a patient-reported questionnaire on the status of the functional joint sets and daily activities. RESULTS: The wrist and neck were the last joints to lose antigravity functionality irrespective of whether the weakness started from the ankle or hip. Two-thirds of the patients could walk either independently or with an aid. The order of losing daily activities could be sorted from standing to eating. Patients with limb-girdle phenotype showed an earlier age at onset than those with foot-drop onset. Patients with biallelic kinase domain mutations tended to progress more rapidly than those with epimerase and kinase domain mutations. CONCLUSIONS: The reported data can guide the clinical management of GNE myopathy, as well as provide perspective to help the development of clinical trials.
Age of Onset ; Ankle ; Disease Progression ; Eating ; Extremities ; Foot ; Hip ; Humans ; Joints ; Muscular Diseases ; Muscular Dystrophies, Limb-Girdle ; Neck ; Pathology ; Phenotype ; Phosphotransferases ; Population Characteristics ; Retrospective Studies ; Surveys and Questionnaires ; Vacuoles ; Wrist