A woman who was not told that her father had a progressive and fatal condition which she might inherit and pass on to her own child has won a stage in her fight for damages.
Known only as ABC, the woman alleges that three NHS trusts owed her a duty of care and were negligent.
On Tuesday, the Court of Appeal said that she had an arguable case to be heard by the High Court.
In 2007, ABC's father shot and killed her mother and was later convicted of manslaughter on the grounds of diminished responsibility.
While detained at a clinic in south London, it was suspected he was suffering from Huntington's Disease and this was confirmed in November 2009.
Huntington's Disease is genetic in origin and, if a parent has it, there is a 50% chance that his or her child will have it as well.
It damages brain cells, causing disruption to movement, cognition and behaviour, and cannot be reversed or slowed.
Medical staff sought the father's consent to disclose the diagnosis to ABC, who was pregnant, but he refused.
In April 2010, ABC's daughter was born and, four months later, she was accidentally told by one of her father's doctors that he had the illness.
In January 2013, ABC was diagnosed with the same condition but it is too early to tell whether her daughter is also affected as it is not usual to test until adulthood.
ABC says it was critical that she should be informed of her father's diagnosis in the light of her pregnancy.
This was her first and only child and it was known all along that she would be a single mother with sole responsibility for its upbringing.
She says that, if she was told, she would have been tested and, if the diagnosis was confirmed, would have terminated the pregnancy rather than risk her child be dependent on a seriously ill parent, become an orphan, or inherit the disease.
ABC claims that she has suffered psychiatric damage because of the failure to inform her, and, if her daughter does have the disease, she will also incur additional expense which would otherwise have been avoided.
In May 2015 in London, Mr Justice Nicol struck out the claim against St George's Healthcare NHS Trust, South West London and St George's Mental Health NHS Trust and Sussex Partnership NHS Foundation Trust on the basis that there was "no reasonably arguable duty of care".
Lady Justice Gloster, Lord Justice Underhill and Lord Justice Irwin allowed ABC's appeal against that decision and remitted the case for trial.