Crumlin Children's Hospital in Dublin will review the transcriptions of all the tests it carried out for detecting a cancer gene.
It comes after it emerged a¬†woman was incorrectly told she didn't have a gene which increases the risk of developing cancer.
The Sunday Times reports that the woman, who doesn't want to be identified, was told in 2009 that she tested negative for the BRCA1 gene.
However, it's been revealed that her doctors were told last month that she actually tested positive.
The woman is now being treated for an aggressive form of ovarian cancer.
In a statement, the Children's Hospital Group apologised to the woman.
It says this is currently considered to be an isolated incident caused by human error.
It adds: "As a precautionary measure, a review by Our Lady's Children's Hospital, Crumlin is currently underway of all transcriptions of BRACA tests to ensure tests results were transcribed correctly and that no similar transcription error has occurred.
"We want to offer reassurance to other patients who have undergone testing that this is not a testing error and therefore there is no cause for concern or distress."
Meanwhile, a spokesperson for Health Minister Simon Harris says the minister has been assured steps are being taken to prevent any further errors in patients being told about the results of cancer gene tests at Crumlin Children's Hospital in Dublin.
The statement adds: "The Minister has asked to be kept updated on these matters and the Hospital Group expects to be in a position to offer a clearer picture early next week."