NEW YORK (AP) — Shares of Genzyme Corp. fell further Monday as potential rival Shire Plc. moved closer to putting a genetic disorder treatment on the market. The competitive threat comes on the heels of Friday’s announcement that the Food and Drug Administration will re-inspect a Boston facility to determine whether certain manufacturing issues are resolved. The stock fell $1.72, or 3.3 percent, to $50.17 in afternoon trading, and fell as low as $49.84 earlier in the trading session, marking its lowest point in about five years. On Friday, shares slid 7 percent following the announcement of the FDA inspection. On Monday, U.K.-based Shire said its Gaucher disease treatment met key goals in a late-stage study. Gaucher disease is an enzyme disorder that can result in liver and neurological problems. If Shire’s velaglucerase is approved, it would compete directly with Genzyme’s Cerezyme. Meanwhile, the FDA accepted Shire’s treatment protocol for the drug, which means physicians can treat patients with the drug prior to traditional FDA approval. The company is asking for approval of the drug using a “rolling submission,” which allows it to submit study findings on an ongoing basis. Shire expects the submissions to be complete by the end of the quarter. The potential threat to Genzyme’s Cerezyme comes as the FDA plans to reinspect the company’s Boston facility to determine whether manufacturing problems discovered in February have been fixed. The company said it fixed the problems and the plant was re-inspected by the agency in May. Meanwhile, the company had to temporarily shut down the production facility in June to clean up viral contamination that had been slowing down the process for making supplies of two biotech-based drugs. The virus, which is not harmful to people, was detected in a bioreactor at the facility. Bioreactors are used in the production of living cells, which are in turn used to make the biotech-based drugs Cerezyme and Fabrazyme. Fabrazyme treats an inherited disorder known as Fabry disease, which is caused by the buildup of a particular type of fat in the body’s cells.