Unexpected detection of Duchenne muscular dystrophy gene mutation by array comparative genomic hybridization in prenatal diagnosis: a retrospective analysis / 中华围产医学杂志

ABSTRACT

Objective:To explore the accuracy of array comparative genomic hybridization(aCGH) in the unexpected detection of Duchenne muscular dystrophy ( DMD) gene duplication/deletion in prenatal diagnosis. Methods:A retrospective analysis was performed on 31 cases with DMD gene duplication/deletion detected by aCGH among 5 025 prenatal diagnosis samples without family history of DMD in Henan Provincial People's Hospital from July 2018 to December 2019. The multiplex ligation-dependent probe amplification (MLPA) method was used to verify the above results. The American College of Medical Genetics and Genomics (ACMG) guideline was referred for pathogenicity analysis of the detected duplicates/deletions. Descriptive analysis was adopted in analysis. Results:The total unexpected DMD gene duplication/deletion rate was 0.62% (31/5 025), among which 25 cases were with microduplication/microdeletion ≤ 200 kb and six were >200 kb; there were 24 cases of deletion, seven cases of duplication; exon or intron duplication/deletion were accounted for 19 and 12 cases, respectively. According to the five classification standards of ACMG guideline, there were 17 cases with pathogenic variants and 14 cases with uncertain pathogenicity/likely benign variants. Of the 19 with exon mutations, 17 cases were DMD intragenic variants, and two cases involved variants in and outside DMD gene, which were verified by MLPA whose results were all positive. Conclusions:The duplication/deletion of exon region of DMD gene detected by aCGH technique is accurate and reliable, which plays an important role in the diagnosis of DMD. For these cases involved both internal and external regions of DMD gene, aCGH can identify the upstream and downstream breaking points of DMD gene, thus providing the basis for ACMG grading.