disease

He said Zipporah was an incredibly caring person, who had dropped out of school in lower sixth to care for her mother who had a neurological disease.

The technique could overcome infertility due to old age or disease, by using almost any cell in the body as the starting point for life.

"My mum's disease is quite progressed now, but the main thing is that we just have learnt to live presently and take each day as it comes, one step at a time."

Beyond the physical health risks - and there are many, including higher risks of cancer and heart disease, plus mental health problems - there may be social consequences too.

Alzheimer's disease is the most common cause of dementia in the UK - but its exact cause is not yet fully understood.