Repligen Corp. has received a $1 million milestone payment from Pfizer under an exclusive worldwide licensing agreement for the development of compounds to treat spinal muscular atrophy (SMA), a neuromuscular disease that typically presents in children under age two.   The companies signed the agreement in January 2013, and since then, Repligen has received $7 million in upfront and milestone payments. Repligen is eligible to receive as much as $63 million in additional milestones, as well as ro...