To treat Pompe disease in the US, the Genzyme Corp. received a significant boost yesterday as the Food and Drug Administration approved for its enzyme replacement drug Lumizyme.

As the news of the drug's approval spread, Genzyme shares shot up 5.5 per cent.

Since 2003, this is one of the most important decisions of the US drug approval for the Cambridge biotechnology company. The worldwide sales are expected to be of at least $1 billion annually that would make Genzyme hopes Lumizyme a blockbuster.

John P. Butler, president of personalized genetic health at Genzyme, said, "This will be our fastest-growing product. The company has spent more than 10 years and $1 billion developing Lumizyme. The United States is the single largest market for this product, and now we have complete access to that market."

The company would be getting the drug shipped from Geel in Belgium and reports state that no other company is marketing a drug for Pompe disease in the United States.

The approval means that about 200 adult patients residing in the US would be sold the drug Lumizyme. About 1, 000 adults who are suffering from the Pompe disease also prospective customers for the company and it can begin marketing the drug to them.