Call the Midwife has gained a reputation for tackling serious medical issues, such as the Thalidomide storyline from a couple of years ago. Now Nurse Phyllis Crane (Linda Bassett) and Nurse Trixie Franklin (Helen George) encounter a devastating disease they've never seen before: Huntington's chorea.
Now more commonly known as Huntington's Disease, this inherited genetic disorder is progressive and is sadly always fatal. It results in the death of brain cells and – even today – it is incurable and untreatable, except for medications which can provide relief from physical symptoms. Life expectancy is usually 15-20 years from when symptoms are first identified.
Huntington's tends to start with subtle shifts in mood and a decline in mental abilities, combined with a general lack of coordination and an increasingly unsteady gait. The problem may not easily be obvious and, before 1993 when the specific gene mutation was identified, doctors had to rely on symptoms and family histories to work out what was going on. (Nowadays, even people without any symptoms can get genetic testing to find out if the disease is in their future.)
From there, as the disease progresses, you will start to see uncoordinated, jerky body movements as well as writhing and rigidity. This cruel disease affects sufferers' ability to coordinate movement and even to speak. Mentally, there will be a decline in cognitive abilities and memory loss which will eventually become dementia.
In most cases, the onset comes between the ages of 30 and 50, but it can affect people of any age – and in 5-10% of cases, symptoms begin before the age of 20.
This is classed as Juvenile Huntington's Disease and, particularly cruelly, the life expectancy is even lower for affected children: the disease progresses rapidly and they tend not to survive more than 10-15 years.
The child of an affected person has a 50:50 chance of inheriting the disease, and Huntington's may also develop earlier in life in each successive generation. It affects men and women equally.
So what would people have known about "Huntington's chorea" in the 1960s? Huntington's is a rare disease, but historical records show that people have been aware of it since at least the Middle Ages.
It was named in 1872 after George Huntington who did a lot of research into the medical side of the disease, and "chorea" means jerky, random and uncontrollable organisations. Medical professionals have known about its hereditary nature as a disorder since the 19th century.