Three novel splicing mutations at 5' terminal of DMD gene corresponding to different phenotypes / 中华医学遗传学杂志

OBJECTIVE@#To study the correlation of splicing mutations at the 5' end of the DMD gene with their phenotypes.@*METHODS@#DMD gene mutations were analyzed using Multiplex Ligation Probe Amplification (MLPA) and Sanger sequencing. Co-segregation analysis was performed for the pedigrees of the probands. Influence of mutations on protein function was predicted by bioinformatic analysis.@*RESULTS@#Three novel splicing mutations were identified in three patients with different phenotypes. Patient 1 carried a c.31+3insT mutation and presented primarily with dilated cardiomyopathy (XLDC). There was no clinical signs of skeletal myopathy. Bioinformatic analysis predicted that the mutation may inactivate the splicing donor of intron 1 and lead to premature termination of protein translation. Patient 2 carried a c.264_264+4delTGTAA mutation, which led to loss of splicing donor site for intron 4, and manifested Becker muscular dystrophy (BMD). The mutation was predicted to result in skipping of exon 4. The defective protein may still retain most of its function. Patient 3 had Duchenne muscular dystrophy (DMD) and carried a c.832-3C>T mutation which was predicted to decrease the activity of splicing acceptor of intron 8, resulting in usage of alternative acceptor site or retain of intron 8. All related transcripts may cause premature termination of protein translation and complete loss of protein function. The three mutations were all inherited from the mothers of the patients.@*CONCLUSION@#Three novel splicing mutations were discovered at the 5' end of DMD gene in three patients with different disease phenotypes. Our study may facilitate understanding of the influence of splicing mutations at the 5' end of the DMD gene on dystrophin function and the correlation between genotypes and phenotypes.

Clinical manifestations and prenatal diagnosis of congenital muscular dystrophy / 中华围产医学杂志

Objective To summarize the clinical features of 22 probands diagnosed with congenital muscular dystrophy (CMD),and to provide genetic counseling and prenatal diagnosis for 23 fetuses of these pedigrees.Methods Data of 22 CMD patients who were treated in the Pediatric Department of Peking University First Hospital during October 2006 to March 2016 were analyzed.Informed written consents for participation in this study were obtained from the parents or guardians.Prenatal diagnosis was performed using DNA samples extracted from fetal villus cells of 12 cases at 11-13 gestational weeks and amniotic fluid of 11 cases at 18-22 gestational weeks.Direct DNA sequencing by polymerase chain reaction (PCR) and multiplex ligation-dependent probe amplification (MLPA) were used to detect CMD-related gene mutations.Linkage analysis of short tandem repeats (STRs) was used to identify maternal blood contamination and biological parents.Results Thirteen out of the 22 probands with CMD were diagnosed with congenital muscular dystrophy type 1 A (MDC1A),and all of them carried compound heterozygous mutations in LAMA2 gene.Prenatal diagnosis of 13 fetuses from these pedigrees found that four fetuses were wild-type,seven were heterozygotes and two carried the same mutations as their proband.Three probands with LMNA-related congenital muscular dystrophy (L-CMD) carried de novo mutations in LMNA gene.In these pedigrees,two fetuses were wild-type and one whose mother was mosaicism carried the same mutations as the proband.One proband with Ullrich congenital muscular dystrophy carried compound heterozygous mutations in COL6A2 gene and the fetus of the same pedigree was wild-type.Five probands were diagnosed with α-dystroglycanopathies.And among them,two cases of muscle-eye-brain disease (MEB) carried compound heterozygous mutations in POMGnT1 gene and the fetuses of the two peidgrees were heterozygotes;one case of congenital muscular dystrophy type 1C (MDC1C) had compound heterozygous mutations in FKRP gene and the fetus carried the same mutations;one patient diagnosed with POMGnT1-related congenital muscular dystrophy with mental retardation (CMD-MR) carried compound heterozygous mutations in POMGnT1 gene,and the fetus was positive for the same mutations;one proband with POMT1-related CMD-MR was positive for compound heterozygous mutations in POMT1 gene and the results of prenatal diagnosis for two fetuses of this pedigree showed that the first fetus had the same mutations as the proband,while the second was heterozygote.Conclusions No effective therapeutic method is available for CMD.Therefore,accurate genetic counseling and prenatal diagnosis are necessary to prevent CMD child from birth.

The clinical presentation and gene mutation of probands in Chinese patients with Charcot-Marie-Tooth disease / 中华内科杂志

Objective To identify the gene mutation of Chinese Charcot-Marie-Tooth (CMT) pedigrees and investigate the association of gene mutation to the clinical manifestations and electrophysiology,and the underlying mechanisms.Methods A total of 105 pedigrees with CMT in our hospital were enrolled from January,2007 to December 2013.The clinical features,CMT neuropathy score (CMTNS) and electrophysiological data were collected.Gene mutations were analyzed using multiplex ligation-dependent probe amplification (MLPA) and Sanger gene sequencing.Results We found 31 (29.5％) PMP22 duplication pedigrees,8 (7.6％) GJB1 mutation pedigrees,4 (3.8％) MFN2 mutation pedigrees,4 (3.8％) HSPB1 mutation pedigrees,3 (2.9％) MPZ mutation pedigrees and 1 (1.0％) PMP22 mutation pedigree.In Chinese Han population,the proportion of PMP22 duplication was relatively lower than that in western countries and manifested with classical clinical characteristics of CMT.Subjects with axonal CMT often presented with isolated lower extremity injury and with central nervous system involvement.Hereditary motor neuropathy might be underestimated in clinical setting and should be differentiated from motor neuron disease.Conclusions The gene frequency distribution in patients with CMT in Chinese Han population is different from that in patients from western countries.We should establish our own epidemiological data of CMT in Chinese Han population.

Muscle magnetic resonance imaging changes and relationship with clinical symptoms in patients with dysferlinopathy / 中华神经科杂志

Objective To investigate the characteristics of muscle edema and fatty infiltration in thighs and relationship with clinical symptoms in Chinese patients with different phenotypes of dysferlinopathy.Methods A total of 32 patients were enrolled , including 13 limb-girdle muscular dystrophy 2B (LGMD2B), 13 Miyoshi myopathy (MM), 4 proximodistal myopathy and 2 hyper-creatine-kinase-emia.Clinical symptoms were evaluated using modified Gardner-Medwin and Walton ( GM-W) score.Muscle MRI was performed in thighs to observe fatty infiltration and edema.We then compared the age of onset , disease duration, GM-W score, muscle edema and muscle fatty infiltration between LGMD 2B and MM groups,and the relationship of muscle edema score and fatty infiltration score with disease duration and GM-W score in all patients.Results The median GM-W score was 4.00 (2.00,5.00) in all patients, 4.00 (3.00,4.50)in LGMD2B and 4.00(2.00,5.00)in MM, respectively.Muscle fatty infiltration appeared in 30 cases (93.75%), with the same pattern in LGMD2B and MM.The mean fatty infiltration score was 28.20 ±12.86 in all patients, 28.50 ±13.03 in LGMD2B and 29.00 ±12.63 in MM, respectively.Muscle edema appeared in 26 cases (81.25%) with same pattern in LGMB2B and MM.The mean edema score was 18.36 ±13.60 in all patients, 22.88 ±11.59 in LGMD2B and 16.77 ±13.80 in MM.The age of onset , disease duration, GM-W score, muscle fatty infiltration and edema score were not significantly different between LGMD2B and MM patients.Muscle fatty infiltration score significantly correlated with GM-W score (rs=0.737,P=0.000) and disease duration (rs=0.637,P=0.000).Conclusions Fatty infiltration and edema in thigh muscles are very common in patients with dysferlinopathy , with similar radiological changes in main subtypes.The muscle fatty infiltration can be used as a predictor of disease progression.

Clinical, myopathological and genetic features in five female manifesting carriers of Duchenne muscular dystrophy / 中华神经科杂志

Objective To analyze the clinical,myopathological and genetic features in 5 female manifesting carriers of Duchenne muscular dystrophy (DMD).Methods The age of onset of these 5 patients were from birth to 54 years old,one of which had a family history of DMD.Two patients presented with proximal weakness,one with myalgia and dilated cardiomyopathy,one with limb weakness and ventricular septal defect,and one with exercise intolerance.Serum creatine kinase concentrations were between 1 000-31 815 U/L.Muscle biopsies were performed in 4 patients.Dystrophin gene mutation analyses were carried out in 5 patients by multiplex ligation-dependent probe amplification.Karyotype study was done in one patient who had no dystrophin gene mutation.Results Muscle biopsy revealed markedly decreased dystrophin expression in one patient and a mosaic pattern with some fibers lacking or partially expressing dystrophin in 3 patients.Four patients were identified carrying exonic deletions of dystrophin gene and one had t(x;5) (p21 ;p14).Conclusions The clinical manifestations and myopathological changes are more compatible with Becker muscular dystrophy.Chromosome translocation can be detected in Chinese female manifesting carrier.

No mutation was detected in the LMNA gene among sporadic Charcot-Marie-Tooth patients / 北京大学学报(医学版)

Objective: To intensively investigate sporadic CMT patients, we have analyzed the LMNA gene in this study in a series of 32 unrelated CMT patients. Methods: Twelve exons of the LMNA gene were amplified from genetomic DNA. PCR products of each exon were analyzed by single strand conformational polymorphism (SSCP). Results: No abnormal SSCP pattern, suggesting no mutation in our CMT patients, was detected. Conclusion: The CMT diseases resulted from the mutations of LMNA gene were rare.

Laminopathies —one gene, multiple diseases / 北京大学学报(医学版)

Laminopathies are genetic diseases that encompass a wide spectrum of phenotypes with diverse tissue pathologies and result mainly from mutations in the LMNA gene encoding nuclear lamin A/C. To date, at least 9 different human diseases, which superficially seem to share little with one another, result from LMNA mutations. The position of the mutation within LMNA appears to be associated with the phenotypes. This review gives an overview of genotype-phenotype relationship and describes recent advances in animal models and pathogenic mechanisms.

Clinical pathological study of the anterior lens capsule abnormalities in familial congenital aniridia with cataract / 北京大学学报(医学版)

Objective: To observe the pathological changes of the lens and anterior lens capsule of the patients with familial congenital aniridia, and discuss the histopathological etiology of the fragility of the anterior capsule and the significance of surgical project. Methods: Anterior lens capsules and lens specimens were obtained from aniridic patients during cataract surgery. The intraoperative behavior of each capsule was noted, after which the specimens were submitted for histopathologic evaluation and electron microscope examination. Results: The anterior lens capsule was extremely fragile and remarkably thin. Degenerative changes(degeneration, necrosis, loss) of the lens epithelium and discontinuity of the lens epithelium were found in some specimens. Proliferation and double layer of the epithelial cells in some area of the specimens can be seen also. Ply structure of the anterior capsule became thin or disappeared. Conclusion: Degenerative or proliferative changes of the lens epithelial cells were associated with the thinness and extreme intraperative fragility of the anterior lens capsules in familial aniridia with cataract. Greater awareness of anterior capsule fragility in some aniridic patients with cataract may reduce the risk of capsule complications and lead to safer surgical outcomes.