  Analysis of the correlation between the angular positions of distant radio
galaxies on the sky and the orientations of their polarization vectors with
respect to their major axes, indicates a dipolar anisotropy in the large scale.
We consider a single mode of large-scale scalar perturbation to the FRW metric.
Using Newman-Penrose formalism, we calculate the rotation of the galaxy major
axis with respect to the polarization vector as the elliptic image and the
polarization vector are carried through the perturbed space-time. The
dependence of the rotation on the polar angular coordinate of the galaxy, is
qualitatively similar to the claimed dipole pattern.
