[Unexpected discovery of a fetus with DMD gene deletion using single nucleotide polymorphism array]

Area of Science:

• Genetics
• Fetal Medicine
• Genomic Medicine

Background:

• Duchenne/Becker muscular dystrophy (DMD/BMD) is a severe genetic disorder.
• Identifying de novo mutations in fetuses is crucial for genetic counseling.
• Standard karyotyping may miss small deletions in genes like DMD.

Purpose of the Study:

• To evaluate the utility of SNP array for detecting de novo DMD gene mutations in fetuses.
• To assess SNP array's effectiveness in cases with unexplained fetal conditions and no family history.

Main Methods:

• Performed G-banded karyotyping and SNP array on fetal amniocytes.
• Utilized multiplex ligation-dependent probe amplification (MLPA) to confirm DMD gene deletions/duplications.
• Analyzed maternal peripheral blood using MLPA.

Main Results:

• Karyotyping revealed a normal 46,XY karyotype.
• SNP array detected a 116 kb deletion encompassing DMD gene exons 17-29 (chrX: 32 455 741-32 571 504).
• MLPA confirmed the fetal deletion but found no mutations in the mother.

Conclusions:

• The identified de novo deletion in the DMD gene may lead to DMD/BMD.
• SNP array enhances the detection of fetal genomic disorders, especially with unknown genes, negative family history, or nonspecific symptoms.