Xu Zibo, a 17-month-old boy, received stem cells transplanted from his twin brother at Shanghai Children's Medical Center last week to treat an inherited metabolic disease.

The stem cell transplant was the first between twins in Chinese history.

Doctors said it will take at least a month to determine if the surgery was a success.

"There is a 80 percent possibility of success. The stem cell is from a sibling, so the patient faces a lower chance of rejection and other complications," said Dr Chen Jing from Shanghai Children's Medical Center. "The best time for a transplant is within one year after delivery."

Xu, a Zhejiang Province native, suffers from mucopolysaccharidosis, or MPS, a rare disease caused by the lack of a specific enzyme. It stunts a child's growth and development, limits the movement of joints and impacts organs.

The condition usually becomes evident in early childhood, as the patient is shorter and has deformed joints and strange appearance. Infected children often die before they reach the age of 10.

Xu's father and mother are both MPS gene carriers, but neither has ever shown signs of the disease. When two gene carriers have a child, there is a 25 percent possibility he will have the disease.

"Our first son was detected with MPS at the age of four. Up till that point we had never heard about the disease and we were told we are both carriers," said Xu Xiao, the father.

Xu's wife became pregnant again in 2004 with twins, and doctors said one fetus was an MPS carrier and the other had the full-blown disease.

"Since doctors said a stem cell transplant can treat the disease, we decided to give birth to the twins," Xu said.

The twins were delivered in September, 2004.

According to Dr Chen, MPS is so rare that ordinary examinations won't diagnose it, but it can be found during a prenatal test.

"Most cases aren't detected until the child starts to show symptoms," Chen said.

(Shanghai Daily April 3, 2006)