The present invention provides methods, kits, and compositions for detecting mutations in transient receptor potential cation channel, subfamily V, member 4 (TRPV4). In particular, mutations are detected in TRPV4 to detect diseases such as scapuloperoneal spinal muscular atrophy (SPSMA) and hereditary motor and sensory neuropathy type IIC (HMSN IIC) or Charcot-Marie-Tooth disease type 2C (CMT2C).