U.S. regulators want to know why Novartis didnt disclose a problem with testing data until after the Swiss drugmakers $2.1 million gene therapy was approved. The Food and Drug Administration said on Tuesday that the manipulated data involved testing in animals, not patients, and its confident that the drug, called Zolgensma, should remain on the market. The agency said its investigating and will consider criminal or civil penalties if appropriate. Zolgensma was approved in May for children under 2, becoming the most expensive treatment ever. Its a one-time treatment for a rare inherited condition, spinal muscular atrophy, which destroys a babys muscle control.