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Pre-selected sibling may cure brother of disease

"We were quite certain that the baby would be a match and the likelihood of success for the procedure of transferring the stem cells into the boy's marrow is quite high."

Su Yi-ning, National Taiwan University Hospital geneticist

The nation's first baby conceived with the help of embryonic pre-selection could help cure her older brother of the hereditary blood disease thalassemia, National Taiwan University Hospital doctors said yesterday.

Like many parents of children suffering from thalassemia, the boy's father and mother, whose names have not been released, decided to conceive another child in a bid to help their son overcome the debilitating disease.

However, an exact donor match is needed to help a sufferer of thalassemia.

For the first time, doctors employed cutting-edge genetic analysis to pre-select an embryo that was an exact donor match.

Following the baby's birth, doctors extracted stem cells from the umbilical cord and will soon implant these into her brother's bone marrow.

If the procedure is successful, his body will then be able to produce blood cells normally.

Doctors said this was possibly the first time the technology had been used in Asia to guarantee donor compatibility.

Without the pre-selection, the chances of the boy's sibling being a suitable donor were less than 25 percent, doctors said.

"There was only a one in four chance that the boy's sibling would have a compatible human leukocyte antigen," said Su Yi-ning (蘇怡寧), a geneticist at the hospital. "Of that 25 percent, one in four would be unsuitable because they would also be carriers of thalassemia."

The doctors were able to ensure that the boy's sibling would be a perfect match by using in-vitro fertilization techniques and testing each of the embryos produced for compatibility before implanting one in the mother.

"As a result, we were quite certain that the baby would be a match and the likelihood of success for the procedure of transferring the stem cells into the boy's marrow is quite high," Su said.

The case has been documented in a study published in this month's issue of the journal Reproductive BioMedicine Online.

The case was particularly difficult because doctors had to test for two factors: whether the embryo was free from thalassemia and whether its antigen was compatible with the patient's.

Su said the university hospital had some experience testing embryos for thalassemia and other genetic diseases caused by a single gene, but only performed such tests in limited cases.

"We only perform the procedure for people with a family history of the disease," Su said.

"If the embryo is tested prior to implantation, it saves the family the agonizing decision of whether to abort a pregnancy at a later stage," Su said.
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