Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy. Duplication of theperipheral myelin protein-22(PMP22) gene is the most frequent genetic abnormality in CMT disease. Although rare compared toPMP22gene mutations, many differentmyelin protein zero(MPZ) gene mutations have been described in patients with CMT disease.MPZgene mutations are known to cause hereditary neuropathies with heterogenous phenotypes ranging from early-onset severe demyelinating to adult-onset axonal forms. MPZ, the major protein component of peripheral nerve myelin, is important for myelin compaction. We report a family in which a mother and her son, both with adult-onset CMT disease, showed a newly described mutation p.Glu37Lys of theMPZgene. The clinical features of the mother provided insight into the progression of the disease over decades, while features in the early stage of the disease could be studied in the son. Clinical, electrodiagnostic, and sonographic findings are described in the early and late stages of the disease. TheMPZgene mutation p.Glu37Lys is associated with clinical features of a progressive axonal type of adult-onset CMT disease.