PLK4 and eye disorder: Of these, 15 genes are expressed in both the eye and brain, namely SORBS3, FKRP, SOX5, PLCH2, TRMT44, POMT2, PCDH15, PLK4, ARL13B, BBS1 B3GALNT2, CDH23, BBS9, SALL4, FKRP. This finding provides new evidence to support the second hypothesis that brain and eye diseases may be affected by the same gene or group of genes at the same time.