It's the long curly hair you notice first as it falls around Kathryn Hazeldine's face.

It's unusual considering her twin brother, Alexander, has straight blonde hair.

It's not the only difference that separates this 5-year-old set of twins.

Alexander doesn't walk, he runs, and he pulls his socks right up to his knees. He also builds huts, has freckles that cover his cheeks and loves his sister whom he affectionately calls Deedee.

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Kathryn, on the other hand, sits quietly with her mum. She plays softly while scanning the room with her eyes. Her legs are still.

When the little girl

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Kathryn's condition