Symptoms of CMT2D include foot deformity, muscle weakness and cramping, compromised reflexes, loss of sensation, and muscle atrophy and are similar to the symptoms of other both CMT1 and CMT2 types. Symptoms and severity vary from patient to patient.Mice are often used to model CMT2D and typically demonstrate aberrant neuromuscular function at the neuromuscular junction (NMJ). The neuromuscular junction is abnormal in CMT2D mice, with subjects showing neuromuscular junction degeneration in hind muscles. The dorsal root ganglia (DRG) is also affected via aberrant sensory neuron fate, meaning that sensory neuron cell fates are abnormally determined. CMT2D mice have fewer proprioceptive and mechanosensitive neurons, but have more nociceptive neurons, possibly due to mutant GlyRS aberrantly interacting with the extracellular region of tropomyosin receptor kinase, or Trk, receptors. Trk receptors are crucial to the survival and development of sensory neurons; when disrupted, nerve development and survival is disrupted as well, possibly leading to the abnormal sensory neuron counts observed in CMT2D mice.CMT2D is a result of autosomal dominant mutations in the human GARS1 gene located at 7p14.3  and is thought to be caused by aberrant gain-of-function missense mutations. The GARS1 gene is a protein-coding gene responsible for the encoding of glycyl-tRNA synthetase (GlyRS). Glycyl-tRNA synthetase is a class II aminoacyl-tRNA synthetase and acts as the catalyst for the synthesis of glycyl-tRNA by covalently bonding amino acids with their corresponding cognate tRNAs for protein translation.
Because this protein is also present in oligodendrocytes, demyelination can appear in the CNS.Schwann cells create the myelin sheath, by wrapping its plasma membrane around the axon.Neurons, Schwann cells, and fibroblasts work together to create a functional nerve. Schwann cells and neurons exchange molecular signals by gap junctions that regulate survival and differentiation.Demyelinating Schwann cells causes abnormal axon structure and function. They may cause axon degeneration, or they may simply cause axons to malfunction.The myelin sheath allows nerve cells to conduct signals faster. When the myelin sheath is damaged, nerve signals are slower, and this can be measured by a common neurological test, electromyography. When the axon is damaged, though, this results in a reduced compound muscle action potential.GARS1-Related Axonal Neuropathy
CMT2 types are typically referred to as axonal neuropathies due to the axonal degeneration observed. CMT2 types are a result of damage to the nerve axons rather than damage to the myelin sheath (as is the case with CMT1). Damaged axons cause slowed transmission of signals to the muscles and brain, causing symptoms including muscle atrophy, weakness, decreased sensitivity, and foot deformity. Symptoms of CMT2 types typically appear between the ages of 5 and 25. CMT2D is one of 31 Charcot-Marie-Tooth type 2 forms 1 and is only diagnosed if sensory deficits (such as loss of sensation due to the degradation of sensory axons) are observed along with motor deficits; otherwise, distal hereditary motor neuropathy type V is diagnosed. It is unknown why sensory involvement is so varied between GARS1 neuropathy patients.