Emmerdale fans are about to see another emotional storyline unfold for Lydia Hart, as she discovers that she may develop Huntington's disease.
Monday's episode (November 18) sees Lydia come face-to-face with her long-lost mother Agatha, who explains that Lydia's father died from the genetic condition. Lydia is shocked to realise that she may also develop the same thing.
What is Huntington's disease and what are the implications of this story for Lydia? Here's what you need to know.
What is Huntington's disease?
Huntington's disease is an inherited condition which affects the brain and nervous system, stopping them from working properly over time. It is caused by a faulty gene and affects both men and women.
If a person's parent has the Huntington's gene, they will have a 50% chance of developing the condition themselves. If affected, that person may also pass the gene on to any children they may have.
Although symptoms of Huntington's disease can begin at any time, they generally become apparent between the age of 30 and 50 years of age.
According to the NHS website, symptoms of Huntington's include difficulty moving, involuntary movements in the body, stumbling and clumsiness, and problems swallowing, speaking and breathing.
Other symptoms can include difficulty concentrating, memory lapses, depression, mood swings and personality changes. However, the condition can affect different people in varying ways, even within the same family.
Sadly, there is currently no known cure for Huntington's disease and it is usually fatal 15 to 20 years after symptoms start to develop. In the later stages of the condition, those with the disease will require full-time nursing care.
Support is available from GPs and organisations like the Huntington's Disease Association on how to manage symptoms and improve quality of life.
Where does Lydia's story go from here?
Emmerdale hasn't yet confirmed whether Lydia does have the Huntington's gene. Upcoming episodes will see her confide in the Dingle family about her discovery, although she isn't sure whether she wants to know either way.
Individuals who have a history of Huntington's disease in their family can choose to have a blood sample taken to find out whether they have the faulty gene which causes the condition.
This process involves sessions with a genetic counsellor, talking through the potential emotional impact and whether the test is right for the individual in question. Some people choose not to know until any symptoms develop.
In an interview about the storyline, Karen Blick – who plays Lydia – explained: "What Lydia doesn't realise [at first] is that there's a 50% chance of her having the same thing. The odds are very high.
"When that dawns on her, it's a massive thing to process and it's a question of whether or not she should take the genetic test to find out. She's not sure and she wonders whether ignorance may be bliss."
She added: "Lydia does tell the rest of the Dingles, but she hasn't quite processed it herself by that point.
"Lydia says that it's something that would happen in the distant future, so they don't need to worry about it now, and the chances are low. But then, later on, Lydia discovers the 50% odds."
Emmerdale airs weeknights at 7pm on ITV, with an extra episode at 8pm on Thursdays.
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