The liquid crystal HOBA exhibits a nematic phase between the achiral smectic C region and the isotropic one. In the nematic phase two subphases N1 and N2 can be distinguished. A shift of the transition temperature N1 - N2 has been observed, if an elastic deformation is involved, with respect to the unidirectional homogeneous case. In the present paper the experimental data concerning a twist distortion are discussed, and a theoretical model is given.