It was only when Alex Waights, 3, started at nursery school that his mother Sarah, 39, began to realise that his speech was not at all normal for his age.

Health visitors had identified nothing wrong with Alex’s development, and while Mrs Waights had wondered whether he might be learning to talk slowly, she put this down to comparisons with her older daughter, Phoebe, now 8.

“Phoebe was fantastically articulate from an early age: at 2, she wasn’t just saying ‘big’, but ‘gigantic’ and ‘enormous’,” she said. “I wasn’t really expecting Alex to be the same, which means we ended up sleep-walking through the gradual revelation of the problem.

“The day the scales dropped from my eyes was when he started pre-school. The other children his age were talking with their parents, saying things like, ‘Mummy, don’t go’. Heavens. Alex was at the stage of saying ‘Daddy! Car!’”

Alex wasn’t able to communicate with other children, which led to behavioural problems as he would shove them to get their attention. His vocabulary was small, he wasn’t joining words into sentences, and his speech was slow and stilted. Yet in other ways, he seemed perfectly normal.

When he was finally assessed as having specific language impairment — a year later than he should have been — the family still found it difficult to get therapy. They decided to pay for private speech and language therapy, at a cost of £45 for hour-long weekly sessions.

Alex is now improving, but Mrs Waights, a writer and PR consultant from Arundel, West Sussex, feels her son’s condition should be better recognised. “I am really angry about how our primary care trust has handled this,” she said. “ SLI falls through the gaps between education and healthcare.

We’re in a world that just doesn’t recognise SLI,” she said. “We’ve even been told that it would be handy to get him an autism label, even though that’s not really appropriate, because that’s something people are used to dealing with.”

Mrs Waights is encouraged by the new research into the genetics of the condition, though she is aware that it will be years before it is translated into diagnostics and therapies.

“If there was a test that could be carried out, even if it’s one that says this child has a higher risk, it would make a huge difference,” she said. “It would also help parents understand that they’re not to blame.

“So often, people just assume that if a child has language problems, it’s because they’ve been neglected. Parents need to know that they’ve not done anything wrong.”

More information about SLI is available from the charity Afasic: www.afasic.org.uk , helpline number 0845 3 55 55 77.

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