Objective:To validate the usefulness of copy number variation sequencing (CNV-seq) in detecting the deletion/duplication of the DMD gene in Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD) patients. Methods:One hundred and seventy-seven cases who visited the Department of Medical Genetics, Affiliated Hospital of Kunming University of Science and Technology/the First People′s Hospital of Yunnan Province from April 2018 to November 2023 were collected. All patients had previously accepted multiplex ligation-dependent probe amplification (MLPA) to detect the deletion/duplication of the DMD gene, including 90 cases of normal control with a negative result of MLPA and 87 cases with the deletion or duplication of the DMD gene (61 cases of DMD and 26 cases of BMD). CNV-seq was performed in a single-blind manner to detect DMD gene deletion or duplication for all of 177 cases to obtain the detection efficiency of CNV-seq in comparison with MLPA. Results:Comparing to MLPA, CNV-seq had a coincidence rate of 88.7% (157/177) for detecting DMD gene deletion/duplication, with a sensitivity of 77.0% (67/87), a specificity and a positive predictive value of both 100.0% (90/90 and 67/67, respectively), a negative predictive value of 81.8% (90/110), and a Kappa value of 0.773. Of the 87 patients with the deletion or duplication of the DMD gene, CNV-seq detected 67 cases with DMD gene deletion/duplication, including 62 cases with deletion and 5 cases with duplication, with fragment ranging from 150 to 750 kb. While CNV-seq missed 23.0% (20/87) of positive cases, mainly due to the involved fragments spanning only 1 to 4 exons, and with a variation size less than 50 kb, below the resolution (100 kb) of CNV-seq. The detection rate of CNV-seq in BMD cases (84.6%, 22/26) was a little higher than that in DMD cases (73.8%, 45/61), but there was no significant difference between 2 subgroups ( χ2=1.211, P=0.271). The results of CNV-seq in normal controls were all negative, and consistent with the results of MLPA. Conclusion:CNV-seq can detect 77.0% (67/87) of deletion/duplication of the DMD gene in patients with DMD/BMD, while the deletion/duplication less than 100 kb may be inevitably unidentified, therefore it is recommended as an assistant screening technique in prenatal diagnosis for DMD gene deletion or duplication.

Objective:To validate the usefulness of copy number variation sequencing (CNV-seq) in detecting the deletion/duplication of the DMD gene in Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD) patients. Methods:One hundred and seventy-seven cases who visited the Department of Medical Genetics, Affiliated Hospital of Kunming University of Science and Technology/the First People′s Hospital of Yunnan Province from April 2018 to November 2023 were collected. All patients had previously accepted multiplex ligation-dependent probe amplification (MLPA) to detect the deletion/duplication of the DMD gene, including 90 cases of normal control with a negative result of MLPA and 87 cases with the deletion or duplication of the DMD gene (61 cases of DMD and 26 cases of BMD). CNV-seq was performed in a single-blind manner to detect DMD gene deletion or duplication for all of 177 cases to obtain the detection efficiency of CNV-seq in comparison with MLPA. Results:Comparing to MLPA, CNV-seq had a coincidence rate of 88.7% (157/177) for detecting DMD gene deletion/duplication, with a sensitivity of 77.0% (67/87), a specificity and a positive predictive value of both 100.0% (90/90 and 67/67, respectively), a negative predictive value of 81.8% (90/110), and a Kappa value of 0.773. Of the 87 patients with the deletion or duplication of the DMD gene, CNV-seq detected 67 cases with DMD gene deletion/duplication, including 62 cases with deletion and 5 cases with duplication, with fragment ranging from 150 to 750 kb. While CNV-seq missed 23.0% (20/87) of positive cases, mainly due to the involved fragments spanning only 1 to 4 exons, and with a variation size less than 50 kb, below the resolution (100 kb) of CNV-seq. The detection rate of CNV-seq in BMD cases (84.6%, 22/26) was a little higher than that in DMD cases (73.8%, 45/61), but there was no significant difference between 2 subgroups ( χ2=1.211, P=0.271). The results of CNV-seq in normal controls were all negative, and consistent with the results of MLPA. Conclusion:CNV-seq can detect 77.0% (67/87) of deletion/duplication of the DMD gene in patients with DMD/BMD, while the deletion/duplication less than 100 kb may be inevitably unidentified, therefore it is recommended as an assistant screening technique in prenatal diagnosis for DMD gene deletion or duplication.

OBJECTIVE: To perform carrier screening for spinal muscular atrophy (SMA) among 3049 reproductive-age individuals from Yunnan region and determine the copy number of survival motor neuron (SMN) gene and carrier frequencies. METHODS: Multiplex ligation-dependent probe amplification (MLPA) was used to determine the copy number of exon 7 of SMN1 and SMN2 genes and identify those with a single copy of SMN1 gene. Prenatal diagnosis was performed for couples whom were both found to be SMA carriers. RESULTS: In total 62 SMA carriers were identified among the 3049 subjects, which yielded a carrier frequency of 1 in 49 (2.03%). No statistical difference was found in the carrier frequency between males and females (1.91% vs. 2.30%, P>0.05). Respectively, 1.3% (41/3049) and 0.69% (21/3049) of the carriers were caused by heterozygous deletion and conversion of the SMN1 gene. The average copy number for SMN1 alleles was 1.99. Two couples were found to be both as SMA carriers, for whom the birth of an affected fetus was avoided by prenatal diagnosis. CONCLUSION No difference was found in the carrier frequency of SMA-related mutations between the two genders in Yunnan region, which was in keeping to an autosomal recessive inheritance pattern. Determination of the carrier frequency for SMA and SMN gene variants may provide a basis for genetic counseling and prenatal diagnosis for the disease.
China ; Female ; Genetic Carrier Screening ; Genetic Counseling ; Genetic Variation ; Heterozygote ; Humans ; Male ; Muscular Atrophy, Spinal ; genetics ; Pregnancy ; Prenatal Diagnosis ; Survival of Motor Neuron 1 Protein ; genetics ; Survival of Motor Neuron 2 Protein ; genetics

Objective:To research on the genetic polymorphism distributions of fifteen short tandem repeat ( STR ) loci (D8S1179,D21S11,D7S820,CSF1PO,D3S1358,TH01,D13S317,D16S539,D2S1338,D19S433,VWA,TPOX,D18S51,D5S818, FGA) in Han race of Yunnan. Methods:A total of 313 specimens were collected from the unrelated individuals in Yunnan Han popu-lation. Genome DNA was extracted and amplified by multiplex PCR technique,the PCR products were analyzed by ABI-3130 genetic analyzer capillary electrophoresis detection, collected statistics of each STR loci genotypic frequency, and carried out the Hardy-Weinberg Genetic balance test. Results: No significant deviation from the Hardy-Weinberg Equilibrium was observed ( P>0. 05 ) , the heterozygosity of the fifteen STR loci in Yunnan Han population were found to be 0. 636-0. 901, Probability match was 0. 034-0. 220. Discrimination power of signal STR loci was 0. 780-0. 966, power of paternity exclusion was 0. 336-0. 797, polymorphism information content was 0. 555-0. 860,the combined accumulation discrimination power and exclusion probability for the 15 STR loci in Yunnan Han population were determined to be more than 0. 999 999 99 and 0. 999 998 408. The allele frequency of the 15 STR loci had a similarity compared with other areas in China,but also had a slight regional differences. Conclusion: The 15 STR loci( D8S1179, D21S11,D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, FGA ) demonstrate high genetic polymorphism in Yunnan Han population, they have a high forensic science application value in paternity testing and individual identification.