Genetic analysis of a gonadal-mosaicism BMD family with prenatal diagnosis and PGT-M / 中华检验医学杂志

ABSTRACT

Objective:To identify the pathogenic characteristics of a suspected gonadal mosaicism Becker muscular dystrophy (BMD) family, and provide provide basis for pregnancy selection of similar families.Methods:A BMD family admitted to Hunan Jiahui Genetics Hospital from June 2012 to September 2019 was systematically reviewed. The medical history and family history of the proband were checked, and multiplex ligation-dependent probe amplification was used to detect the deletion/duplication of 79 exons of the Duchenne muscular dystrophy (DMD) gene in the proband, fetuses, and parents. Moreover, potential variants were verified by combining PCR amplification, short tandom repeat polymorphic linkage analysis, and real-time fluorescence quantitative PCR. High-quality embryos are screened for transplantation after preimplantation genetic testing for monogenic (PGT-M). And amniotic fluid was collected in the second trimester for prenatal diagnostic verification.Results:According to the phenotype analysis of the proband, the initial clinical diagnosis was BMD, and the exon 45-50 deletion in DMD gene was detected. The mutation was not detected in the mother′s peripheral blood, but when she was pregnant again, the prenatal diagnosis showed that the fetus had the same deletion mutation as the proband. Neither of two vitro embryos tested by PGT-M has the deletion mutation, then single embryo transfer was performed nor was pregnancy successful. After confirmation of prenatal diagnosis during pregnancy, a normal baby girl was born by full-term cesarean section.Conclusions:This BMD family was a family with two consecutive BMD homodeletion mutations, and the mutation of the DMD gene was not detected in the peripheral blood of the proband′s mother and two embryonic cells, suggesting that the mother may be a gonad chimeric carrier of this deletion mutation. The combined application of prenatal diagnosis and PGT-M provides a reference approach to effectively avoid the birth of similar children.