"This research is one of the first clinical trials to assess whether a drug can improve brain function in people with an inherited disorder.
"The potential benefits of this treatment include an improved quality of life for affected patients and wider benefits for their families and carers.
"If it works it will benefit patients directly and could provide clues as to whether this class of drugs (called mTOR inhibitors) might have wider benefits in problems like autism."
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A rather wet and windy evening, with rain in the north and showers elsewhere.
The 19-year-old's body was discovered in Builth Wells last month, just days after he was reported missing at the Royal Welsh Show.
The funeral has taken place of a one-year-old girl who died when a parked car rolled into a wall, which then collapsed on her.