Dystrophinopathies, including Duchenne muscular dystrophy, Becker muscular dystrophy and dilated cardiomyopathy, are X-linked recessive genetic disorders due to variants of the dystrophin gene, which can seriously affect quality of life and health. Genetic diagnosis plays a crucial role in their diagnosis, treatment, and prevention. How to rationally select and standardize the use of various genetic techniques is a skill that clinicians must acquire. By compiling expertise of experts from the relevant areas and guidelines published home and abroad, this consensus has provided a guidance from the perspective of genetic diagnosis for the selection of genetic techniques, testing strategies, and detection process for dystrophinopathies.
Humans ; Quality of Life ; Consensus ; Dystrophin/genetics* ; Muscular Dystrophy, Duchenne/therapy* ; Cardiomyopathy, Dilated/genetics* ; Electrocardiography

OBJECTIVE: To explore the genetic basis for 7 families with gonadal mosaicism for Duchenne muscular dystrophy (DMD). METHODS: For the 7 families presented at the CITIC Xiangya Reproductive and Genetic Hospital from September 2014 to March 2022, clinical data were collected. Preimplantation genetic testing for monogenic disorders (PGT-M) was carried out for the mother of the proband from family 6. Peripheral venous blood samples of the probands, their mothers and other patients from the families, amniotic fluid samples from families 1 ~ 4 and biopsied cells of embryos cultured in vitro from family 6 were collected for the extraction of genomic DNA. Multiplex ligation-dependent probe amplification (MLPA) was carried out for the DMD gene, and short tandem repeat (STR)/single nucleotide polymorphism (SNP)-based haplotypes were constructed for the probands, other patients, fetuses and embryos. RESULTS: The results of MLPA showed that the probands and the fetuses/probands' brothers in families 1 ~ 4, 5, 7 had carried the same DMD gene variants, whilst the probands' mothers were all normal. The proband in family 6 carried the same DMD gene variant with only 1 embryo (9 in total) cultured in vitro, and the DMD gene of the proband's mother and the fetus obtained through the PGT-M were normal. STR-based haplotype analysis showed that the probands and the fetuses/probands' brothers in families 1 ~ 3 and 5 have inherited the same maternal X chromosome. SNP-based haplotype analysis showed that the proband from family 6 has inherited the same maternal X chromosome with only 1 embryo (9 in total) cultured in vitro. The fetuses in families 1 and 6 (via PGT-M) were both confirmed to be healthy by follow up, whilst the mothers from families 2 and 3 had chosen induced labor. CONCLUSION Haplotype analysis based on STR/SNP is an effective method for judging gonad mosaicism. Gonad mosaicisms should be suspected for women who have given births to children with DMD gene variants but with a normal peripheral blood genotype. Prenatal diagnosis and reproductive intervention may be adapted to reduce the births of further affected children in such families.
Male ; Pregnancy ; Child ; Humans ; Female ; Muscular Dystrophy, Duchenne/diagnosis* ; Dystrophin/genetics* ; Mosaicism ; Exons ; Prenatal Diagnosis/methods* ; Nucleotides

OBJECTIVE: To explore the genetic basis of a Chinese pedigree affected with Becker muscular dystrophy (BMD) with myalgia as the main feature. METHODS: Clinical data of the patients and results of auxiliary examinations were retrospectively analyzed. Multiplex ligation-dependent probe amplification and high-throughput sequencing were used to detect potential variants. Sanger sequencing was used to verify the results. RESULTS: The clinical manifestations of the proband included myalgia and elevated serum creatine kinase, which is similar to another patient from the pedigree. Genetic testing revealed that the two patients both harbored hemizygous deletions of exons 10 to 29 of the DMD gene, for which the mother was a carrier. The same deletion was not found in his father. Based on the guidelines from American College of Medical Genetics and Genomics, the deletion was predicted to be pathogenic (PVS1+PM2+PP1). CONCLUSION Myalgia with elevated serum CK may be atypical clinical manifestations of BMD and may be associated with variants in the rod domain of the DMD gene. The deletion of exons 10 to 29 of the DMD gene probably underlay the BMD in this pedigree.
China ; Dystrophin/genetics* ; Female ; Genetic Testing ; Humans ; Muscular Dystrophy, Duchenne/genetics* ; Myalgia/genetics* ; Pedigree ; Retrospective Studies

OBJECTIVE: To carry out pedigree analysis for a rare child with comorbid X-linked ichthyosis (XLI) and Duchenne muscular dystrophy (DMD). METHODS: Whole exome sequencing (WES) and multiple ligation-dependent probe amplification (MLPA) were used to detect potential deletions in the STS and DMD genes. RESULTS: The proband was found to harbor hemizygous deletion of the STS gene and exons 48 to 54 of the DMD gene. CONCLUSION The child has comorbid XLI and DMD, which is extremely rare.
Child ; Dystrophin/genetics* ; Exons ; Gene Deletion ; Genetic Testing ; Humans ; Ichthyosis/genetics* ; Muscular Dystrophy, Duchenne/genetics* ; Mutation

OBJECTIVE: To summarize the genetic characteristics of 671 Chinese pedigrees affected with Duchenne/Becker muscular dystrophy (DMD/BMD). METHODS: Clinical data of the pedigrees were collected. Multiplex PCR, multiple ligation dependent probe amplification (MLPA), next generation sequencing (NGS), Sanger sequencing and long read sequencing were used to detect the variant of DMD gene in the probands and their mothers, and prenatal diagnosis was provided for high risk pregnant women. RESULTS: Among 178 pedigrees analyzed by multiplex PCR, 44 variants of the DMD gene were detected, with the genetic diagnosis attained in 110 pedigrees. Among 493 pedigrees analyzed by MLPA in combination with NGS or Sanger sequencing, 294 pathogenic/possible pathogenic variants were identified, among which 45 were unreported previously, and the genetic diagnosis attained in 484 pedigrees. Structural variants of the DMD gene were identified in two pedigrees by long-read sequencing. Among 444 probands, 341 have inherited the DMD gene variant from their mothers (76.8%). Among 390 women with a high-risk, 339 have opted to have natural pregnancy and 51 chose preimplantation genetic testing for monogenetic disease (PGT-M). The detection rate of neonatal patients and carriers following natural pregnancy was significantly higher than that for PGT-M. CONCLUSION Combined application of MLPA, NGS, Sanger sequencing and long-read sequencing is an effective strategy to detect DMD/BMD. PGT-M can effectively reduce the risk of fetuses. Above finding has expanded the spectrum of DMD gene variants and provided a basis for reproductive intervention for pregnancies with a high risk for DMD/BMD.
China ; Dystrophin/genetics* ; Exons ; Female ; Genetic Testing ; Humans ; Infant, Newborn ; Multiplex Polymerase Chain Reaction ; Muscular Dystrophy, Duchenne/genetics* ; Mutation ; Pedigree ; Pregnancy ; Prenatal Diagnosis

OBJECTIVE: To summarize the result of genetic testing and therapeutic prospect of 2042 unrelated Chinese pedigrees affected with Duchenne/Becker muscular dystrophy (DMD/BMD) from a single center from 2005 to 2019. METHODS: Peripheral blood samples of the pedigrees were collected for the detection of DMD gene variants with combined multiple ligation-dependent probe amplification (MLPA), next generation sequencing (NGS) and Sanger sequencing. RESULTS: DMD and BMD have respectively accounted for 78.60% and 21.40% of the pedigrees, which included 33 female probands. Variants of the DMD gene were detected in 1986 pedigrees (97.26%). Large deletions, duplications and small-scale mutations have respectively accounted for 71.85%, 8.76% and 19.39%. Common deletions and duplications have included deletion of exons 45-50 and duplications of exon 2, while no hot spot was found with small-scale mutations. For 1595 pedigrees affected with DMD, 935 (58.62%) were hereditary and 660 (41.38%) were de novo in origin. 34.28% (700/2042) of the patients had symptoms which could be relieved by gene therapy. CONCLUSION This has been the largest single-center study of DMD pedigrees, which has attained definite diagnosis in 97.26% of the patients. The results have enabled genetic counseling and prenatal diagnosis for the affected families upon their subsequent pregnancies, enriched the spectrum of DMD gene variants, as well as facilitated study of the mechanism of DMD gene mutations and exploration of clinical treatment.
China ; Dystrophin/genetics* ; Exons/genetics* ; Female ; Gene Deletion ; Genetic Testing ; Humans ; Muscular Dystrophy, Duchenne/therapy* ; Mutation ; Pedigree ; Pregnancy

OBJECTIVE: To establish a newborn screening system for Duchenne muscular dystrophy (DMD) through assessment of MM isoenzyme of creatine kinase (CK-MM) activity. METHODS: The CK-MM level was detected using dry blood spot filter paper from 10 252 male newborns. The results were grouped based on their gestational age, sampling time and intervals between the experiments. The threshold value for CK-MM necessitating genetic testing was determined. Next-generation sequencing (NGS) was carried out for those with a CK-MM value over the threshold, and the result was verified by multiplex ligation-dependent probe amplification (MLPA). RESULTS: Based on the result of non-parametric rank sum test, the median CK-MM concentration has increased with the gestational age, and was inversely correlated with the age of the newborns among unaffected specimens. CK-MM on dry blood spot filter paper can be stable for 14 days at 2-8℃. Statistical analysis of CK-MM value of the 10 252 neonates suggested that the threshold may be set as 700 ng/mL. Exonic deletions were found in 2 confirmed cases, whose CK-MM level was greater than 2000 ng/mL. CONCLUSION Detection of CK-MM in dry blood spot filter paper has provided an effective method for newborn screening of DMD. This simple and inexpensive method can be used for large-scale screening, which is of great value to the early intervention and treatment of the disease.
Dystrophin/genetics* ; Exons ; Humans ; Infant, Newborn ; Male ; Multiplex Polymerase Chain Reaction ; Muscular Dystrophy, Duchenne/genetics* ; Neonatal Screening

OBJECTIVE: To identify the etiology of a patient with severe symptoms of DMD and to trace its pathogenic gene, so as to provide a basis for genetic counseling and clinical intervention. METHODS: Multiple ligation-dependent probe amplification (MLPA) technique was used to analyze exon deletion/repetitive variant of DMD gene, and further analysis was performed by chromosome G-banding, fluorescence in situ hybridization (FISH) and SNP array analysis. RESULTS: The MLPA results of the proband showed that the exon 1-79 of DMD gene were deleted, the G-banding karyotype of blood sample was 46, XY, and the deletion of the short arm of X chromosome was found by FISH. SNP array results showed that 5.8Mb (29 628 158-35 434 714) deletion occurred in the Xp21.2p21.1 region of X chromosome, and the patient was diagnosed as the contiguous deletion syndrome involving the genes of IL1RAPL, MAGEB1-4, ROB, CXorf2, GM, AP3K7IP, FTHL1, DMD, FAM47A, TMEM47, and FAM47B. CONCLUSION The exact pathogenic site of this family is the deletion of 5.8 Mb (29 628 158-35 434 714) in the Xp21.2p21.1 region of X chromosome, which can be used for prenatal diagnosis. High resolution SNP array technique plays an important role in detecting potential chromosome abnormalities in patients.
Dystrophin/genetics* ; Exons ; Female ; Gene Deletion ; Humans ; In Situ Hybridization, Fluorescence ; Muscular Dystrophy, Duchenne/genetics* ; Pregnancy ; Prenatal Diagnosis

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.
Dystrophin ; genetics ; Humans ; Muscular Dystrophy, Duchenne ; genetics ; Mutation ; Phenotype ; RNA Splicing

OBJECTIVE: To carry out genetic testing and prenatal diagnosis for a family affected with Duchenne muscular dystrophy (DMD). METHODS: Multiplex ligation dependent probe amplification (MLPA) was used to detect potential deletion and duplication of the Dystrophin gene. Haplotype analysis was performed using five short tandem repeat polymorphism loci (3'-STR, 5'-STR, 45-STR, 49-STR, 50-STR of the DMD gene. RESULTS: A same deletional mutation (exons 51-55) of the DMD gene was detected in two brothers but not in their mother. The patients and fetus have inherited different haplotypes of the Dystrophin gene from their mother, suggesting that the fetus was unaffected. CONCLUSION The mother was very likely to harbor germline mosaicism for the Dystrophin gene variant. Genetic testing of peripheral blood samples cannot rule out germline mosaicism in the mother. Prenatal diagnosis should be provided for subsequent pregnancies in this family.
Dystrophin ; genetics ; Exons ; Female ; Gene Deletion ; Germ-Line Mutation ; Humans ; Male ; Mosaicism ; Muscular Dystrophy, Duchenne ; genetics ; Pregnancy ; Prenatal Diagnosis