GJC2 and pathologic nystagmus: Some point mutations in Cx47 (e.g., p.Ile33Met, p.Ser48Leu, p.Pro87Ser, p.Pro90Ser, p.Arg260Cys, p.Glu263Lys, p.Tyr272Asp, p.Met286Thr, and p.Met283Thr), and a frameshift mutation in Cx47 [23,24] have been identified in patients with HLD2, who often have nystagmus, spastic ataxia, and hypomyelination/demyelination.