THE SECOND of four brothers who suffer from a rare genetic condition has successfully undergone a lifesaving bone marrow transplant.

Eight-year-old Daniel Hartley received the transplant at London's Great Ormond Street Hospital.

The exact date of the vital operation is being kept secret because Daniel was receiving his transplant from a mystery donor.

Health rules say that there must be anonymity between donor and recipient.

The family are due to release a statement later this afternoon, when David Hartley and son Nathan, 10, will speak at the Anthony Nolan Trust's 30th anniversary celebration in London.

Daniel is one of four brothers suffering from one of the world's rarest genetic disorders, called X-linked Lymphoproliferative syndrome, or XLP.

The disorder has been dubbed a "time bomb" and sufferers must receive bone marrow transplants if they are to live past their teens.

When the Hartleys, who live in Romsey, first discovered the devastating news about their boys last November, they faced odds of millions to one to save their sons.

But Daniel's successful transplant is another milestone in an extraordinary appeal, launched about Easter of this year.

The story captured people's imaginations and a staggering 18,000 Hampshire people signed up to the Anthony Nolan Trust's bone marrow register.

It was discovered that mum Allison was a match for eldest son Joshua, 12.

The Romsey School pupil received his lifesaving transplant in the summer - and the Daily Echo told how friends at the family's New Life Church, in Romsey, were holding round-the-clock prayer meetings during crucial moments.

In July, the family confirmed that a match had been found for Nathan and Luke, 4, and the two brothers are due to have their crucial transplants sometime next year.