UK Boy has world's rarest Genetic Disorder

Every little boy is unique to their parents but six year old Mackenzie Fox-Byrne is also special to the scientific world. He is thought to have the world's rarest genetic disorder because he is the only person on earth known to suffer from it.

Mackenzie, whose condition has given him learning difficulties and left him unable to speak, is the result of a gene mutation doctors have never seen before.

his development appeared to be behind that of her other children, Kamara, 14, and Katie, 12.

At three months old, he was still not lifting his head from his cot, he found it difficult to hold down food and had trouble sleeping.

Doctors initially feared he might have the muscle-wasting disease Muscular Dystrophy, but instead tests results showed a much more bewildering picture.

Mrs Fox-Byrne, 40, of Market Drayton, Shropshire, said: "They knew it was unique and told me excitedly that they had found something rare that no one else has.

"Unfortunately, that was all they could tell me. They couldn't tell me how he is going to progress or whether he might fall ill in the future.

"No one else on earth has ever had this condition."

Mackenzie's test results showed he had a triplication of a small region on the long arm of his X-chromosome.

At the moment the little boy cannot speak, has low muscle tone, is still in nappies and has no sense of danger.

He also has learning difficulties which mean he has the mental age of a two-year-old and goes to a special school in Shrewsbury.

Mrs Fox-Byrne, who lives with her partner Andy, 47, said: "It's quite terrifying to be told he is the only person in the world to have this condition.

"Although we worry about what might happen to him in the future, I just try to put it out of my mind. You could go crazy thinking about it."

Karen Temple, professor of medical genetics at Wessex Clinical Genetics Service confirmed Mackenzie was a totally unique case.

She said: "We have to learn what we can from the little boy as he grows up.

"The problem with Mackenzie isn't that he has got genes missing – as is the case sometimes – it's that he has got extra parts.

"This little boy has had this chromosome problem since he was conceived, we can learn from how he is now and that helps us to predict his future."