The condition the three children were suffering from meant they were unable to talk or walk and were slowly dying.
It has been described as an incredibly debilitating disorder.
The four-year-old girl was diagnosed first followed by the younger twin boys.
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David Cameron said the Met proved it can "do more with less" and declined to criticise the Mayor of London for his water cannon spend.
A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.