A woman sues the London NHS trust for not revealing her father had been diagnosed with Huntington's disease before he had his own child.
He only discovered he was carrying a gene for degenerative brain disorders and was incurable after his daughter was born.
The woman later learned that she also carried the wrong gene, which meant her daughter had a 50% chance of having it.
The NHS said that the case increased competition for nursing duties and confidentiality issues.
The plaintiff is known as ABC to protect the identity of his daughter, who is now nine years old.
The facts of this case are tragic. In 2007, ABC's father shot and killed his mother.
He was convicted of murder on the grounds of reduced responsibility and detained under the Mental Health Act.
It is suspected that he may suffer from Huntington's disease, a fatal neurological condition that progressively destroys brain cells.
Huntington influences movement, cognition, and usually causes behavior change and often aggression.
When her diagnosis was confirmed in 2009 by doctors at St. George's NHS Trust, ABC's father explained that he did not want his daughter to be notified. He tells her that she is pregnant.
He told the doctor that he was worried he might commit suicide or have an abortion.
Four months after his daughter was born, ABC was accidentally notified of his father's condition.
He was tested and found that he had inherited the Huntington gene, which meant he would eventually develop the disease.
His daughter has not been tested, but will have a 50:50 chance to inherit it.
The woman accused that St. George's NHS Trust owes him an assignment to inform his father's diagnosis, bearing in mind the doctor there knows he is pregnant.
ABC said he would immediately carry out genetic testing and would stop the pregnancy, rather than letting his daughter risk inheriting illness or having to care for seriously ill parents.
At that time, ABC and his father were undergoing family therapy organized by the NHS, so he argued that there was an obligation to protect his psychological or physical health.
This is the foundation of the doctor / patient relationship, but it is not absolute.
Disclosure of personal information, without the patient's consent, can be justified to prevent others from being exposed to the risk of death or serious harm.
- Around 8,500 people in the UK have Huntington's disease and a further 25,000 will develop it when they are older
- This is a rare congenital disorder that damages certain nerve cells in the brain
- Huntington generally affects people in their prime – in their 30s and 40s – and patients die about 10 to 20 years after symptoms begin
- Some patients describe it as Parkinson's disease, Alzheimer's and motor neurones combined into one
This case was first debated in the High Court in 2015 when a judge ruled that a full trial should not proceed.
The ruling said "there is no duty of debate that can be reasonably debated" owes to ABC.
But in 2017, the Court of Appeals overturned the decision and said that the case must be tried.
If ABC wins this case, it will trigger a major change in the rules governing patient confidentiality, and raise questions about possible care assignments that must be paid to family members after genetic testing.
Emily Jackson, a law professor at the London School of Economics, said: "If a patient does not want his doctor to tell his children about his terminal diagnosis, for example, or his HIV status, then it goes without saying that doctors must respect patient confidence.
"The complicating factor with genetic diagnosis is that it is not only information about individual patients, but also reveals that relatives are at risk.
"Under such circumstances, and where relatives can act on that information, should doctors' duties be extended to close family members of patients?"
A spokesman for the NHS Trust St George's Healthcare said: "This case raises complex and sensitive issues with respect to competing interests between care duties and confidentiality duties.
"The court will try these matters during the trial."
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