CHIT1 and proximal spinal muscular atrophy: The study by Freigang et al. analyzed CHIT1 in 58 adult and 21 pediatric SMA patients (types 1–3) with a median age of 31 years, comparing them to an age- and sex-matched control group of 30 individuals (23 healthy, 7 with non-neuroinflammatory conditions) [70].