Two new medications for treating a rare and deadly neuromuscular disease have high prices and questionable efficacies, say scientists.

The announcement by Novartis, the maker of Zolgensma, has drawn mixed reactions from the spinal muscular atrophy community.

The animals lived longer and showed milder symptoms than untreated mice, although they didn’t survive as long as wildtype mice.

At $2 million for a single dose, Novartis’s Zolgensma is the most expensive medicine to date, but still less expensive over a lifetime than another approved drug for the rare genetic disease.