Baby Ben Kutschke was diagnosed at 3 months old with spinal muscular atrophy, a rare inherited disorder which is the leading genetic cause of death in infancy globally. It leaves children too weak to walk, talk, swallow or even breathe.

So in 2021, when his parents heard about Zolgensma — a one-time therapy costing millions of dollars that promises to replace genes needed for the body to control muscles — they had high hopes.

They were disappointed.