MISSED BY OTHERS, DETECTED BY US
IriSight® Case Study

Partial DOK7 deletion plus small indel explains multiple fetal anomalies

Clinical presentation

A multigravida underwent an anatomy scan at 21 weeks gestation. In addition to IUGR and hydrops fetalis, the following fetal findings were noted:

  • Abnormal heart morphology
  • Hepatomegaly
  • Small stomach
  • Echogenic bowel
  • Arthrogryposis, joint contracture
  • Rocker bottom foot
  • Hand clenching

Previous genetic testing

Testing was performed with negative results including:

  • Chromosomal microarray

IriSight® Testing

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

Results and interpretation

Variantyx IriSight® testing identified a paternally inherited, likely pathogenic 10.87 kb deletion encompassing DOK7 exons 3-4. Along with a second, maternally inherited, pathogenic c.1263dup DOK7 variant.

Diagnosis: DOK7-related disorders

IGV view of DOK7 variants

Uniform data from WGS clearly shows the partial DOK7 deletion (top) and the small sequence change (bottom).

The Variantyx Difference

Why were these variants detected by IriSight® testing, and not detected by chromosomal microarray?

  • The size of the 10.87 kb deletion falls below the cut-off value for CMA (~25 kb).

  • CMA is unable to detect small sequence changes.
    Variantyx genome analysis has a detection range from 1 bp to whole chromosomal events, easily detecting the copy number variant as well as the small sequence change.

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