- FXTAS is rare among Portuguese patients with movement disorders: FMR1 premutations may be associated with a wider spectrum of phenotypes. Seixas, A.I., Vale, J., Jorge, P., Marques, I., Santos, R., Alonso, I., Fortuna, A.M., Pinto-Basto, J., Coutinho, P., Margolis, R.L., Sequeiros, J., Silveira, I. Behav. Brain. Funct (2011)