The proband presented at 9y with 2 years of red, painful, itchy feet, distal ulcers, tachycardia, hypermobility and growth retardation. Gabapentin was ineffective, leaving him crying, depressed/anxious, and out of school. Lower-leg PGP9.5-immunolabeled skin-biopsy revealed abnormal epidermal neurite density (END) at 0.08% of predicted. Mexiletine gave immediate pain relief, and he flourished with improved functioning, growth, and resolved depression/anxiety. At 12.5y, he self-weaned medications, restarted school, and maintained nearly symptom-free remission for 3y with his 13.3y post-treatment biopsy normalized to 60.8%. His variant-bearing brother started holding and rubbing his feet at 2y. At 4.2y, his skin biopsy was normal (48.7%), but symptoms persisted and growth slowed. Initiating carbamazepine at 4.6y resolved his distress, improved his growth, and also his 6.1y skin-biopsy (54.5%). Their variant-bearing mother with milder, untreated erythromelalgia since 9y also had profound axonopathy (END <0.01%). 1.75y of mexiletine also induced continuing 3y remission, during which she delivered a 3rd variant-bearing child, asymptomatic at 8mo. Mother’s post-treatment biopsy at 37y was also normal (11.8%). Her affected father had subclinical "hot feet", erectile dysfunction, and irritable bowel since mid-40s. At 57y, his evaluation revealed reduced foot sweating and normal END (85.0%); oxcarbazepine was initiated.