(Reuters) -The U.S. Food and Drug Administration has declined to approve a higher-dose version of Biogen's drug for a rare genetic disorder that causes progressive muscle weakness, dealing a setback to the company's efforts to strengthen its position in a competitive market, the company said on Tuesday.

The health regulator has requested an update to technical information on the drug, Spinraza, to be included in the Chemistry Manufacturing and Controls module of the company's application, Biogen said.

The company did not immediately respond to Reuters' request for comment.

Spinraza was first approved in 2016 to treat spinal muscular atrophy, which is the leading inherited cause of infant death.

The FDA's decision casts uncertainty over the company's efforts to revitalize its spinal muscular atrophy franchise, which has been losing ground to newer, more convenient therapies.