Evaluation of Single Exon Deletions in DMD/BMD: Technical and Analytical Concerns.

BACKGROUND

Oftentimes, a variation at the multiplex ligation-dependent probe amplification (MLPA) probe binding site leads to improper hybridrization/ligation of the probe showing up as a deletion of an exon leading to false positive results for the detection of Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD).

OBJECTIVE

Investigating cases with single exon deletion using an alternate method [polymerase chain reaction (PCR) or sequencing] for confirmation of the deletion.

METHODS

We evaluated males with single exon deletion (n = 49) in our study population (2015-2019). Forty-six were confirmed by an alternate method (conventional PCR/Sanger's sequencing) to confirm the deletion.

RESULTS

We observed 25.12% single exon deletions in our study cohort. Further evaluation determined a false positive rate of 6.12%. Three out of 49 single exon deletions had a point mutation near the probe-binding site, indicating a false positive result. Single exon deletions, thus, need to be evaluated with extreme caution, and point mutations, if any, need to be characterized to determine the nature of their pathogenicity.