A case of congenital spinal muscular atrophy with pain due to a mutation in TRPV4.

We present a patient with congenital spinal muscular atrophy associated with pain, subjective sensory loss, right talipes equinovarus, delayed walking, and progressive gait impairment. A sister and niece reportedly had Charcot-Marie-Tooth 1A, but the patient's electromyogram showed an axonal motor neuropathy or neuronopathy. We identified a c.806G>A TRPV4 gene mutation causing an Arg269His amino acid substitution. TRPV4 mutations cause variable phenotypes including axonal sensorimotor neuropathy and motor neuropathy or neuronopathy. Associated features may include arthrogryposis, skeletal dysplasia, vocal cord paresis, sensorineural hearing loss and respiratory weakness. Skeletal X-rays can identify orthopedic causes of pain in patients with TRPV4 mutations, and imaging evidence of bone deformities in patients with suspected hereditary axonal neuropathy, pain and an unknown genetic diagnosis may help lead to a diagnosis of a TRPV4 mutation. Even when a patient's genetic diagnosis is presumed to be known, electrodiagnostic testing is warranted to verify the diagnosis.