However, another study [43] suggested an activating role for 2B4 in HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), correlating with SAP levels, which was higher in patients with HAM/TSP compared to asymptomatic HTLV-1 infected individuals, and lowest in uninfected controls. Here, SH2D1A is linked to tropical spastic paraparesis.