MISSED BY OTHERS, DETECTED BY US
Genomic Unity® 2.0 Case Study

UPD and aberrant methylation confirm clinical Prader-Willi syndrome diagnosis

Clinical presentation

A 7-month-old female with a history of premature birth and small size for gestational age presented with the following symptoms:

  • Hypotonia
  • Failure to thrive
  • Developmental delay

Previous genetic testing

Prader-Willi syndrome was suspected, however multiple tests were performed with negative results including:

  • FISH for Prader-Willi/Angelman syndrome
  • Mitochondrial genome sequencing
  • Whole exome sequencing

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 maternal, partial UPiD of ~42Mb at 15q11.2q22.31 and maternal, partial UPhD of ~36Mb at 15q22.31q26.3.

MAGEL2 and SNURF regions are normally paternally expressed, but show extra methylation consistent with maternal UPD.

Diagnosis: Prader-Willi syndrome

Genomic Unity® 2.0 long-read sequencing makes it possible to identify aberrant Chr15 methylation.

The Variantyx Difference

Why was Genomic Unity® testing able to identify the presence of uniparental disomy and hypermethylation that was missed by other tests?

  • Uniparental disomy is not readily detected by FISH or exome sequencing.
    Variantyx genome analysis detects all major variant types in a single test including small sequence changes, mitochondrial variants, repeat expansions and structural variants. It easily detected the uniparental disomy while simultaneously ruling out other variant types.

  • Methylation status can not be detected by FISH or exome sequencing. 
    With dual short and long-read sequencing, Genomic Unity® 2.0 enables methylation analysis of the chromosome 15 region associated with Prader-Willi syndrome.

*While all of these tests would have identified the uniparental disomy, only Genomic Unity® 2.0 would provide the additional methylation pattern data.

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