CNTN2 and tropical spastic paraparesis: Human T cell leukemia virus type I (HTLV-I) is etiologically linked to adult T cell leukemia (ATL) [1, 2] and a chronic progressive neurological disorder termed HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) [3, 4].HTLV-I genome contains a unique 3′ region, designated as pX, which encodes the viral transactivator protein, Tax [5].