Background: Uner Tan syndrome, first described in\ud
2005, consists of three main symptoms: habitual\ud
locomotion on all four extremities, impaired\ud
intelligence, and dysarthric or no speech. This\ud
extremely rare syndrome shows an autosomal\ud
recessive inheritance due to consanguineous\ud
marriages between parents. In general, there is a\ud
cerebellovermial hypoplasia with a mild gyral\ud
simplification in the cerebral cortex. Truncal ataxia is\ud
the main neurological finding, causing difficulty in\ud
standing and upright walking on two legs.\ud
Methods: As soon as the new cases came to light, the\ud
family was visited. After taking the basic information\ud
about the family members, the traditional neurological\ud
examinations were performed, MRI scans of the\ud
patients and of a healthy family member were taken in\ud
a hospital nearest to the residence (a small village\ud
near Kars, Turkey). The patients were also filmed to\ud
analyze their walking patterns.\ud
Results: Two individuals (case 1, 44y; case 2, 43y)\ud
among six siblings from a family with consanguineous\ud
parents exhibited Uner Tan syndrome, with\ud
quadrupedalism, impaired intelligence, and dysarthric\ud
speech. Their pedigree suggested an autosomal\ud
recessive inheritance. MRI scans showed inferior\ud
cerebellovermial and pontobulbar hypoplasia.\ud
Case 1 did not display hypotonia, while case 2 had\ud
been hypotonic for two years after birth. Case 2’s\ud
hypotonia progressively disappeared, and at three\ud
years old he started to sit, and could walk on all fours\ud
by the age of four. Case 1 was quadrupedal for 20\ud
years, and then walked upright with the aid of a\ud
walking stick. Tendon reflexes were normal in case 1\ud
but hyperactive in the lower extremities of case 2;\ud
Babinsky was absent in case 1 but bilaterally present\ud
in case 2. There was no nystagmus, no strabismus,\ud
and no pes pedus in either case. Cognition was\ud
severely impaired in both.\ud
Conclusion: The emergence of quadrupedalism\ud
during development, with a transition into bipedalism\ud
in case 1, and the emergence of the quadrupedalism\ud
after a full hypotonia and no locomotion in case 2,\ud
were considered as examples of the processes of\ud
adaptive self-organization, from the viewpoint of\ud
dynamic systems theory
