GPR143 and pathologic nystagmus: In summary, we investigated five Chinese families with X-linked nystagmus and identified five mutations in GPR143 including four novel mutations, c.333G>A (p.W111X), c.360+1G>C, c.659-1G>A and c.43_50dupGACGCAGC (p.L20PfsX25), and a previously described mutation of c.703G>A (p.E235K).