Anomaly Description Rules

If the VeriSeq NIPT Assay Software v2 – RUO analysis identifies an anomaly, the anomaly_description field in the NIPT Report displays the value DETECTED followed by a string of text. This text describes all reportable anomalies based on the International Standing Committee on Cytogenetic Nomenclature (ISCN) style. The string contains multiple elements separated by semicolons. Each element represents a trisomy or monosomy in an autosome, a sex chromosome aneuploidy, or a partial deletion or duplication.

Trisomy and monosomy elements are noted as +<chr> and -<chr>, respectively, where <chr> is the chromosome number.

For example, a sample with a trisomy on chromosome 5 appears as follows:

+5

A sample with a monosomy on chromosome 6 appears as follows:

-6

Sex chromosome aneuploidies use standard notation, with the following possible values:

•

XO - for monosomy on chromosome X.

•

XXX - for trisomy on chromosome X.

•

XXY - for 2 X chromosomes in males.

•

XYY - for 2 Y chromosomes in males.

Partial deletions or duplications only report for autosomes and only appear in genomewide screenings. The syntax of a partial deletion or duplication is <type>(<chr>)(<start band><end band>), where the following is true:

•

<type> is the event type, either del for deletion or dup for duplication.

•

<chr> is the chromosome number.

•

<start band> is the cyto band containing the start of the event.

•

<end band> is the cyto band containing the end of the event.

For example, a partial deletion or duplication in which the cytoband at p13 on chromosome 19 has a duplication appears as follows:

dup(19)(p13.3,p13.2)

The anomaly_description field follows four ordering rules:

1.

Elements are ordered by the chromosome number, regardless of whether an entire chromosome or a partial deletion or duplication. A sex chromosome aneuploidy, if present, appears last.

2.

For anomalies within the same chromosome, whole chromosome aneuploidies come before partial deletions or duplications.

3.

For partial deletions or duplications within the same chromosome, deletions come before duplications.

4.

Partial deletions or duplications of the same type within the same chromosome are ordered by the starting base, which appears in the Supplementary Report.