Genzyme (Nasdaq: GENZ) just can't catch a break. The company said last week that its supply of Fabrazyme, which treats Fabry disease, would continue to be constrained. The company has had trouble meeting demand since its manufacturing plant had to be temporarily closed and cleaned more than a year ago.

Yesterday, the European Medicines Agency took swift action recommending new patients and those who can't get enough drug start or switch to Shire's (Nasdaq: SHPGY) Replagal.

The recommended switch shouldn't have a long-term effect, unlike the government favoring Gilead Sciences' (Nasdaq: GILD) HIV drug over GlaxoSmithKline's (NYSE: GSK) drug. But it's likely to last longer than the six months that the recommendation is currently in effect for. Many patients who start Replagal in the next six months will probably just stay with that drug as long as it's working for them.

And prescriptions into next year may be affected because Genzyme has essentially opened the doctor's office door for its competitor. Many doctors would prefer to prescribe Fabrazyme, but now they'll have additional experience with Replagal whether they wanted it or not, which could lead to fewer prescriptions for Fabrazyme well into the future.

Genzyme is working on a new plant to manufacture Fabrazyme, but it won't be approved until the end of next year. Until then, another water issue in Boston, rioting Sox fans, or who knows what else could set off another supply disruption.

With all the troubles Genzyme has had, it's hard to recommend buying shares. You'd be in good company if you do go for the bad-news-buy, but with so many high-quality companies, why gamble on a potential turn around candidate that might have yet another stumble down the road?