The Gap Junction Protien gene, also known as (GJB1/CMTX1 OMIM 304040), encodes for the connexin 32 protein, a gap junction protein that facilitates the transfer of ions and small molecules between cells (Bergoffen, J et al. Science 1993;262:2039-2042). The GJB1/CMTX1 gene, located at Xq13.1, contains 2 exons. Mutations in GJB1/Cx32 result in X-linked dominant Charcot-Marie-Tooth disease (CMTX). CMTX is characterized by peripheral neuropathy, white matter lesions, absence of deep tendon reflexes, and pes cavus deformity of the foot (Ikegami, T et al. Am J of Med Genet 1998;80:352-355).