Story of Ms. Savitha

The first reported case of an X-chromosome variant detected by NIPT, confirmed by karyotyping but missed by FISH, involved Savitha (name changed), a 24-year-old woman from Delhi who was pregnant with her first child. She was referred for non-invasive prenatal testing (NIPT) after her biochemical screening indicated a high risk.

The Claria NIPT results showed a low risk for trisomies 21, 18, and 13, but indicated a high risk of monosomy X (Turner syndrome). She was therefore advised to undergo confirmatory amniocentesis. The fluorescence in situ hybridisation (FISH) report showed no numerical abnormalities in any of the five chromosomes tested. In view of the discordant results, the sample was re-tested by NIPT to rule out any laboratory error. The repeat NIPT result was consistent with the initial finding.

Three weeks later, the karyotype analysis confirmed the presence of a rare variant of Turner syndrome.