A rare genetic distal arthrogryposis syndrome with characteristics of plantar flexion contractures typically presenting with toe-walking in infancy, variably associated with milder contractures of the hip, elbow, wrist and finger joints. No ocular or neurological abnormalities are associated and serum creatine phosphokinase levels are normal.

Autosomal recessive distal hereditary motor neuronopathy-6 (HMNR6) is a neuromuscular disorder characterized by onset of distal muscle weakness in early infancy. Affected individuals often present at birth with distal joint contractures or foot deformities and show delayed motor development, often with inability to walk or frequent falls. Hypo- or hyperreflexia may be observed; limb muscle atrophy may also be present. Patients often show respiratory distress or diaphragmatic palsy. Electrophysiologic studies are consistent with a peripheral motor neuropathy without sensory involvement (Maroofian et al., 2019). For a discussion of genetic heterogeneity of autosomal recessive distal HMN, see HMNR1 (604320).