MISSED BY OTHERS, DETECTED BY US
Genomic Unity® Case Study

DMD inversion provides genetic diagnosis, enabling access to treatment options

Clinical presentation

A 16-year-old male had been denied access to DMD  trials and vamorolone treatment due to lack of a molecular diagnosis, despite presenting with a clinical diagnosis of Duchenne muscular dystrophy based on muscle biopsy results and hallmark symptoms:

  • Motor developmental delays, large calves, toe walking, frequent falls, loss of independent ambulation at age 10
  • Elevated CK levels
  • Restrictive lung disease

Previous genetic testing

Multiple tests were performed with negative results including:

  • DMD gene sequencing (x2)
  • DMD del/dup analysis (x2)
  • Dystroglycan-related congenital muscular dystrophy panel

Genomic Unity® Testing

was ordered because of its ability to identify all major variant types in a single test.

Genomic Unity® Testing

Variantyx Genomic Unity® testing identified a hemizygous, pathogenic 713kb inversion encompassing exons 45-57 of the DMD gene.

The inversion is expected to result in loss of function which is consistent with prior RNA analysis identifying an intronal inclusion that leads to an inability to produce dystrophin.

Diagnosis: Duchenne muscular dystrophy

Uniform data from WGS identifies the breakpoints of the 713kb inversion spanning DMD exons 45-57.

The Variantyx Difference

Why was this inversion detected by Genomic Unity® testing, and not detected by other targeted DMD tests?

  • Balanced rearrangements like inversions are undetectable by most available technologies – including MLPA and targeted gene sequencing.
    Variantyx genome analysis detects many types of structural variants including copy number variants, deletions/duplications, inversions, mobile element insertions, regions of homozygosity and aneuploidy.

  • Both inversion breakpoints are intronic, adding to the complexity of detection.
    Variantyx genome analysis includes intronic regions, enabling breakpoint detection regardless of location.

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