With advances in gene technology helping to diagnose very rare diseases, has the new era of personalised medicine finally arrived?
Evie Walker sits on her mothers lap, playing a game she never grows tired of: turning her mothers hand over and over, stroking and examining it. When she takes a break and looks around, it is with the open-mouthed look of curiosity and awe that you see in many infants. Evies vocabulary currently consists of a repertoire of squawks and mmm sounds. In the past few months, she has begun to stand unaided for short periods even taking a few steps in her walking frame progress that fills her parents with immeasurable pride, not to mention hope for the future.
Despite her baby-like demeanour, Evie is eight years old. She has Pura syndrome, a vanishingly rare developmental disorder that didnt officially exist until four years ago. Developmental disorders affect childrens normal mental or physical development. Before she was diagnosed, all Evies parents knew was that she suffered from global developmental delay: a vague umbrella term for a set of symptoms with myriad potential causes some, but not all of them, associated with aheartbreakingly poor prognosis.
Yet thanks to advances in genome sequencing, more and more families like the Walkers are receiving an accurate diagnosis for their childs condition, and with it a clearer picture of what the future holds. In some cases, such as Evies, it reveals they are suffering from a completely new disease; in others albeit a minority of cases, for now it reveals a potential treatment for acondition that had hitherto seemed untreatable.
Its not only children with developmental disorders whose lives are being transformed by this technology. In October 2018, NHS England will launch its Genomic Medicine Service, 13 genomic medicine centres that will provide whole genome sequencing to people with undiagnosed rare diseases and cancer another disease of mutated genes.
By uncovering the exact genomic changes driving tumour growth, doctors can choose more effective treatments. In so doing, the NHS says England will become one of the first countries in the world to routinely offer comprehensive and equitable access to the latest in genomic testing and management for the whole country, regardless of condition and where people live. People with developmental diseases and cancer will be the first to benefit, but as our understanding of genetics grows, the infrastructure will be in place for the testing of other disorders as well, such as early onset dementia or multiple sclerosis, which may be caused by several gene variants.
Ever since the announcement that a first draft of the human genome had been sequenced, scientists and politicians have been claiming were on the threshold of a new era of personalised genomic medicine. Has it finally arrived?
Evie was Alison Walkers second child, born 15 months after her first. Walker had sailed through both pregnancies, and when Evie was delivered, a week overdue, by normal vaginal delivery, it appeared her parents had been blessed with a second healthy child and an excellent sleeper to boot. But this attribute rapidly became a source of concern. Her parents had to wake her to feed her, and then she didnt feed for very long. She also felt abnormally cold. Walker raised these concerns with her health visitor when Evie was five days old, and she was told to take her to hospital.
Immediately, the triage nurse grabbed her and raced off down the corridor. Evie spent a week in intensive care while the medical team worked to keep her warm and fed. We assumed it was just a little bump in the road, that shed get better, and then wed go home with our gorgeous little girl and all would be well, says Walker.
But even though Evie returned home, she remained extremely sleepy, and as she turned from infant to toddler, it became clear that she wasnt hitting the usual developmental milestones. She regularly returned to hospital, undergoing blood tests for various hormonal and nutritional deficiencies, brain scans to detect neurological damage and genetic tests for common inherited diseases. Her parents naively assumed that one of these tests would eventually reveal how to fix Evies issues: Then we started to realise that not only could we not fix it, we couldnt figure out what the problem was to start with, Walker says.
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