SAN RAFAEL -- BioMarin Pharmaceuticals (Nasdaq:BMRN) shares jumped by more than 30 percent Monday after the company announced a key study on its GALNS therapy ended, the first step in seeking regulatory approval for its treatment of the rare enzyme deficiency condition.

The new medication is aimed at treating Mucopolysaccharidosis Type IVA, also known as Morquia A syndrome, a rare condition that is usually the result of an enzyme deficiency that can trigger bone and skeletal disorders. Only about 3,000 patients have been diagnosed with the disorder.

While that may be a small number, the development of a therapy for it is a top priority for the San Rafael-based maker developer of treatments for rare disorders.

"The GALNS clinical program is currently the highest development priority at BioMarin, and this positive phase III study services as a potentially transformative milestone for the company," Jean-Jacues Bienaime, chief executive officer of BioMarin, said in a statement. "We are applying our track record of success in developing novel treatments for orphan diseases and our existing commercial infrastructure for Naglazyme to bring GALNS to patients as rapidly as we can." 

The price of BioMarin stock Monday increased 31.2 percent, or $11.09 a share, to $49.07 and was up another dime a share in after-hours trading. The price reached an all-time high of $49.52 at one point Monday.

The study found that patients who were given a weekly dose of 2 milligrams per kilogram of patient weight of GLANS, also called BMN-110, showed improvement in walking distance by 22.5 meters in six minutes. Additionally, patients who took GLANS for 24 weeks showed better stair-climbing ability, as well as improvements in lung function.

BioMarin said it expects to file for marketing approval early next year.

"The positive results from this pivotal study will help support GLANS as the first therapy available to help the approximate 3,000 people worldwide suffering from MPS IVA -- a rare, degenerative, life-threatening genetic condition with no available therapy," Hank Fuchs, M.D., BioMarin chief medical officer, said in a statement. "We look forward to reviewing the results of this study with regulatory authorities, and applying for marketing authorizations starting in the first quarter of 2013."