  The study of ionized gas morphology and kinematics in nine eXtremely
Metal-Deficient (XMD) galaxies with the scanning Fabry-Perot interferometer on
the SAO 6-m telescope is presented. Some of these very rare objects (with
currently known range of O/H of 7.12 < 12+log(O/H) < 7.65, or Zo/35 < Z <
Zo/10) are believed to be the best proxies of `young' low-mass galaxies in the
high-redshift Universe. One of the main goals of this study is to look for
possible evidence of star formation (SF) activity induced by external
perturbations. Recent results from HI mapping of a small subsample of XMD
star-forming galaxies provided confident evidence for the important role of
interaction-induced SF. Our observations provide complementary or new
information that the great majority of the studied XMD dwarfs have strongly
disturbed gas morphology and kinematics or the presence of detached components.
We approximate the observed velocity fields by simple models of a rotating
tilted thin disc, which allow us the robust detection of non-circular gas
motions. These data, in turn, indicate the important role of current/recent
interactions and mergers in the observed enhanced star formation. As a
by-product of our observations, we obtained data for two LSB dwarf galaxies:
Anon J012544+075957 that is a companion of the merger system UGC 993, and SAO
0822+3545 which shows off-centre, asymmetric, low SFR star-forming regions,
likely induced by the interaction with the companion XMD dwarf HS 0822+3542.
