Research In Clinical And Genetic Characterization For Female Carrier Of Dystrophinopathies

Objective This study aims to summarize clinical characteristics among female carriers of Dystrophinopathy and analysis dystrophin gene mutations among female carriers.Methods1.DMD Suspected patients using MLPA and NGS detected DMD gene exons.2.On already confirmed diagnosed proband‘s maternal female relatives MLPA applications and Next generation sequencing was performed to clarify its genetic identity.3.Negative results for MLPA and NGS to detect genes that cause other myopathy required further testing to confirm diagnosis;4.Analyse clinical data of female carriers along with DMD gene mutations and summarize the clinical characteristics and gene mutations.Results1)Among total 73 female relatives of proven DMD proband using MLPA and NGS techniques,35cases(47.95%)were confirmed female carriers,2 cases of germinal mosaicisim,and 6 other cases of high CK level.Among 35 proven carriers,includes four cases of symptomatic female carriers.Muscle weakness as main clinical manifestation.Other2 female relatives done MLPA and NGS,result was negative for DMD gene showed other muscular dystrophy diagnosis as limb gridle muscular dystrophy.2)Two cases of symptomatic female carriers underwent skeletal muscle biopsy, nmuscle biopsy results showed a small amount of muscle fiber connective tissue proliferation,few stromal small vessels have small amount of granulocytes,lymphocytes infiltrate,muscle fiber necrosis,regeneration is not obvious,comply pathological muscular dystrophy changes.3)Among these 35 were confirmed as female carriers with gene analysis.Exon deletion mutations accounts 40.00%,exon duplication mutations accounts 14.29% and Point mutations accounts45.71%.Deletion mutations hot spots at the exon 45-50 and the exon 2-19,same as studies have two hotspots;reported duplication mutations hotspots at the 3 ’end of the DMD gene and other studies reported 5’ end.4)Two cases of DMD probands mothers were negative for DMD exonsmutations using MLPA and NGS but both probands,his mother and sister allhave different levels of CK increased,and the MLPA confirmed the probandand his sister exons of X chromosomes carry the same deletions,so,it is considered these two probands mothers have germinal Mosaicisim;Other six negatively tested MLPA and NGS female relatives with CK abnormally high, could not exclude the possibility being DMD carriers.5)Among 35 cases of female carriers in 25 cases had increased creatine kinase(CK),along with aspartate aminotransferase(AST),alanine aminotransferase(ALT)significant increase level,and the serum femalecarriers CK and AST(r = 0.888,p <0.01),ALT(r = 0.919,p <0.00) were positively correlated.ALT has strong correlation comparatively to AST with CK.Conclusions1.The serum creatine kinase level is non-invasive easy and excellent screening for affected cases of DMD manifesting carriers and strongly correlated with ALT and AST.2.MLPA technique can detect missing exon large fragment of symptomatic female carriers of dystrophin gene.MLPA along with DNA sequencing can determine carrier‘s status.3.DMD female relatives with a negative results of genetic testing to have another baby commended to make prenatal diagnosis,especially family who have other female members and the proband with the same mutations or negative results of genetic testing but CK unusually high,female relatives should emphasize the necessity and should make prenatal diagnosis.4.Muscle biopsy may assist in identifying genetic identity of DMD carriers, especially when genetic testing negative,but biopsy should be performed to confirm the diagnosis.