Evaluation and management of DMD gene copy number variations detected by prenatal SNP-array testing

This study aims to evaluate the clinical management of incidental findings of copy number variations (CNVs) in the DMD gene detected through prenatal single nucleotide polymorphism array (SNP-array). Prenatal SNP-array testing was performed on samples exhibiting CNVs in the DMD locus, followed by parental analysis using the same technique. Additionally, multiplex ligation-dependent probe amplification (MLPA) testing was conducted on prenatal cases and their parents. Pregnancy outcomes were documented, and postnatal follow-up was conducted. SNP-array analysis identified copy number variations at Xp21 affecting either the entire DMD gene or only a portion of it in 14 fetuses. In 11 cases, MLPA testing confirmed the presence of deletions or duplications detected by the SNP-array. High-density SNP-array platforms with low reporting thresholds may incidentally detect a subset of exon-level copy number variations involving the DMD gene during routine prenatal testing and thereby contribute to early recognition of potential dystrophinopathy-related variants. Suspected DMD-related CNVs, especially exon-level alterations, require confirmation by targeted assays such as MLPA or next-generation sequencing, together with cautious clinical interpretation. Assessing the pathogenicity of prenatally detected DMD copy number variations remains challenging, particularly for duplications, which require careful evaluation. Furthermore, the sequential, time-intensive nature of confirmatory and familial studies often limits definitive risk assessment within the prenatal decision-making window, and introduces broader familial implications that must be navigated through careful, multidisciplinary counseling.