Usually, bone marrow transplants are the only option for such infants, who can die from organ failure. Bone marrow transplants can be difficult to get and donors are rare.
Umbilical cord blood, however, can be donated with every birth and also contains immature cells known as stem cells that can restore missing or damaged cells in a patient.
Stem cells are the body's master cells and there are several kinds. Stem cells from the bone marrow or cord blood are partly differentiated, or transformed, and can be used to restore the immune systems of patients undergoing cancer treatment, for example.
Dr. Vinod Prasad and colleagues at Duke University in North Carolina studied 159 children with inherited metabolic disorders who received transplants of cord blood from unrelated newborns at Duke between 1995 and 2007.
"We saw that there were advantages to the unrelated cord blood transplant," Prasad said in a statement.
"For instance, cord blood is more readily available than bone marrow and there was a decreased risk of complications, including a lower incidence of serious and potentially fatal graft-versus-host disease, which occurs when donor cells perceive a recipient's tissues and organs as foreign."
Speaking to an American Society of Hematology meeting in Atlanta, Prasad said more than 88 percent of patients who got cord blood transplants before they began to show too many symptoms of illness lived for at least a year.
"One reason for this could be the cord blood cells are immunologically more naive than the blood-forming stem cells derived from bone marrow and therefore they may be more adaptable and less reactive once they get into the patient's body," he said.
One metabolic disease Prasad's team treated is Krabbe disease, also known as Krabbe leukodystrophy, which affects the nervous system. Another is Hurler disease, which affects the heart, liver and brain.
"These disorders are rare when taken individually - some of them occur in only one in a million births - but if you put them together they have a sizable incidence, maybe one in 10 000 births," Prasad said.