Webmedcentral WebmedCentral Neurosciences 2046-1690 WebmedCentral 5017 research-article Neurosciences Gait Analysis in Uner Tan Syndrome Cases with Key Symptoms of Quadrupedal Locomotion, Mental Impairment, and Dysarthric or No Speech Uner Tan Senior Researcher,Cukurova University Medical School ,Turkey * E-mail:

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11 2015 10 11 2015 5 7 WMC005017 09 11 2015 10 11 2015 Copyright: © 2011 Webmed Ltd 2011





In 1887, Eadweard Muybridge reported the first case of a person walking on all fours, in a child with a paralyzed leg [1]. In this context, Price [2] noted ââ¦not only was the regular system of limb movements used, but the support of the body devolved, in their proper sequence, on the lateral and on the diagonals.â This child typically exhibited straight legs during quadrupedal standing. A man with healthy legs walking on all fours was discovered by Childs [3] in Turkey, 1917. Childs [3] described this man as follows: âI saw that he was without thighs; that the knee-joint was at the hip, the leg rigid, and only half the usual length. With his grim bearded face thrust upwards, and the odd movements of his little legs, he lacked only a stump of tail to make me think I had come upon a satyr in life.â This man exhibited habitual QL with straight legs. He had tattered and torn trousers (Illustration 1). Habitual QL, mental impairment, and poverty were the characteristics of all of the UTS cases [4].Â  Â  About a century later, in the years 2004-2005, Turkish media reported five siblings of a consanguineous family with 19 children, residing in a village near Iskenderun beneath the Syrian border. The Â five siblings exhibited habitual QL, accompanied by severe mental retardation, and dysarthric speech. At the time the discovery attracted little interest Â among scientists.Â  Because I was deeply interested in, and had worked on, the extensor and flexor motor systems since 1960, I visited this family and investigated the affected siblings neurologically, radiologically, and cognitively with my colleagues [4]. After an âAha!â experience [5], I realized the affected siblings were affected by a novel syndrome. This was called Uner Tan syndrome (UTS) after its discoverer [6,7]. I described the condition as âlocomotor evolution in reverse in humans,â or in short, âlocomotor devolutionâ [6,7], to highlight the reappearance of an ancestral locomotion in human beings.Â  Â Â Â  Despite obtaining extensive video recordings, I performed no quantitative gait analysis of the UTS cases. Instead, I made simple gait analyses by observing that the still photos showed ipsilateral limb interferences. I therefore described their walk as (DS) because ipsilateral limb interferences frequently occurÂ  in nonhuman primates with DS walking, and indeed, the ipsilateral limb interference is a potential drawback of a diagonal walk [8-10]. âDS gaits often result in limb interference [11, 12],â as noted by Young et al. [13]; âa diagonal sequence/diagonal couplet walking gait creates a strong potential for interference between the ipsilateral hind and forelimbsâ [12]; ââ¦its associated ipsilateral limb interference in DS gait.â [10]; â âipsilateral interlimb interference is very high for DSDC walkingâ [14], in which the hind foot touchdowns are followed by the contralateral fore foot touchdowns. In a lateral sequence (LS) walking gait, the hind foot touch downs are followed by the ipsilateral fore foot touchdowns [13].Â  The idea that nonhuman primates exclusively prefer the DS walking gait is not in accord with the scientific literature. Namely, Sellers et al. [15] found a mixture of DS and LS gaits in nonhuman primates when they used a computer simulation of chimpanzee locomotion, suggesting a mixture distribution of the DS and LS walking in these primates. Hildebrand [8] and Cartmill et al. [9], early experts in gait analysis, also found a broad spectrum of gaits with footfall overlaps in nonhuman primates.Â  In humans, Shapiro et al. [16] carried out a biomechanical gait analysis of a few UTS cases belonging to a single family and a few healthy individuals requested to use QL. They reported the UTS cases exhibited LS walks almost exclusively, unlike the DS walking gaits of nonhuman primates. Consequently, these authors suggested the UTS cases may not reflect a locomotor reappearance of ancestral human QL. That is, Tanâs theory of reverse locomotor evolution in humans [6,7] would not be tenable, provided that nonhuman primates were our ancestors [16]. However, I had discovered 33 cases in 10 families since finding the first family with UTS in 2005 [17]. Thus, more families with UTS cases needed to be subjected to a quantitative gait analysis, to be conclusive about their type of QL. The essential questions to be answered by a more comprehensive study of cases from the 10 families were: (i) do the UTS cases use LS and/or DS walking gait?; (ii) how might the locomotion of UTS cases be related to that of nonhuman primates?; (iii) are the UTS cases examples of a locomotor evolution in reverse, provided that present-day nonhuman primates could be considered to be similar to our ancestors, at least with regard to locomotion. In the present work, a postural and locomotor gait analysis was performed on videos of a larger sample of UTS cases, with healthy individuals with requested and free QL, and nonhuman primates, to answer these questions.


To assess the quadrupedal posture while standing on four extremities, the hip and knee angles were measured using the âUniversal Desktop Ruler v3.6.3481â software. These measurements were performed on photographs of the UTS cases (Group 1, n = 32), adults with requested straight-leg QL (Group 2, n = 27), adults with free (flexed-leg) QL (Group 3, n = 53)), adult terrestrial primates (Group 4, n = 24: bonobos, baboons, chimps, gorillas, and rhesus monkeys), and adult arboreal primates (Group 5, n = 31): loris, lemur, propithecus, and marmoset), as depicted in Illustration 2.Â Â  The UTS cases (Group 1, n = 32) from 10 families voluntarily took part in the study, and video footages of them were used for the gait analyses. Group 2 included 27 healthy individuals asked to use QL keeping their legs straight; the adult terrestrial primates constituted Group 3 (n = 53); healthy individuals using flexed-leg QL included Group 4 (n = 24); adult arboreal primates constituted Group 5 (n = 31).Â  Â Â Â  . A gait analysis was performed on videos of UTS cases and other groups. The UTS cases were filmed with a digital video camcorder at 25 frames/sec.Â  Â  Limb phases were measured from the video footage, âas the percentage of a hind limbâs stride duration that the touchdown of a forelimb follows that of the hind limb on the same side of the bodyâ, following Shapiro et al. [16]. Gait numbers (limb phases), were as follows: 0 (or 100) corresponds to a pace, 1-24 represents LSLC, 25: LSSF, 26-49: LSDC, 50: trot (diagonal limbs landing simultaneously), 51-74: DSDC, 75: DSSF, and 76-99: DSLC. LS, LC, DS, SF, and DC were abbreviations for lateral sequence, lateral couplet, diagonal sequence, single foot, and diagonal couplet, respectively. Sequence meant the order of footfalls in time. In a DS walk, a reference hind limb touches the ground and then the contralateral forelimb touches the ground. In an LS walk, a reference hind limb touches the ground and then the ipsilateral forelimb touches the ground [16]. Gait analysis included only the symmetrical walking strides between 40 and 60% for the fore and hind limbs [11].Â  Informed and written consent was taken from a responsible person before the investigations. The study was approved by the ethics committee of the Cukurova University, following the Helsinki declaration. Statistical analyses were performed using SPSS V. 22 (IBM Corp., 2012, USA).






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Figure legends

Illustration 1: First discovered man with habitual QL in Turkey in 1917 [3]. Notice the hip (1) and knee (2) angles. Illustration 2: Quadrupedal postures in the UTS cases (A1-A3), healthy individuals with straight- leg quadrupedal posture (B1-B3), nonhuman primates (C1: chimpanzee, C2: macaca mulatta, C3: macaque), healthy individuals with free (natural) quadrupedal postures (D1-D3), and nonhuman primates with arboreal QL (E1: slow loris, E2: grey mouse lemur, E3: propithecus.Â  Notice primates with large (C: terrestrial) and small (E: arboreal) bodies.Â Â Â Â  Illustration 3: Means and SDs of the hip and knee angles Illustration 4: Error bars with Â±2.0 SD for the hip (open circles, red) and knee (filled circles, black) angles of the UTS cases (UTS), healthy individuals with requested QL, straight legs (FORCED QL), terrestrial primates with free quadrupedal standing (PRIMATE1), healthy individuals with free (flexed legs) QL (NORM QL), and arboreal primates with free quadrupedal standing (PRIMATE2).Â  Illustration 5: Mean limb phases with Â±2.0 SDs for five study groups. UTS cases (UTS);Â  FORCED QL: healthy individuals with requested straight-leg QL; FREE QL: healthy individuals with free QL; BABIES QL: babies with QL; PRIMATES QL: terrestrial nonhuman primates QL. Notice the differences and similarities in these subgroups. Illustration 6: Percentages and minimum-maximum limb phase values for five study groups

Cover letter

Dear Editor: I would like to submit my revised paper entitled âGait Analysis In Uner Tan Syndrome With Quadrupedal Locomotion, Mental Impairment, And Dysarthric Or No Speech, for possible publication in the Journal of WebmedCentral). Uner Tan syndrome was first identified in 2005 as a unique syndrome characterized by the habitual use of quadrupedal locomotion, severe truncal ataxia, dysarthric or no speech, and severely impaired intellectual abilities. No quantitative gait analysis was carried on these cases Â until 2014, when the QL was characterized by others as lateral sequence similar to healthy human adults, but in a small sample size from only one family. The submitted work included a representative sample size from 10 families hitherto discovered in Turkey, and reports a new quantitative gait analysis of Uner Tan syndrome cases, healthy human infants, healthy human individuals and nonhuman primates. It addresses the fact that UTS cases walk with straight rather than flexed legs, and the results show that while the QL is mostly lateral sequence, there are similarities in gait characteristics with terrestrial primate locomotion, whereas the QL in healthy individuals had similarities with arboreal primate locomotion. These findings have implications in the evolution of bipedal locomotion in human beings and in the quadrupedal locomotion in UTS cases.Â  I hope the findings and conclusions in the paper all make this manuscript worthy of publishing. Yours faithfully, Prof. Dr. Uner Tan, M.D., Ph.D. Honorary member of the Turkish Academy of Sciences, Ankara, Turkey E-mail: unertan37@yahoo.com


Jera Kruja Head of Neurology Service, University of Medicine, Tirana; University Service of Neurology, , Albania Gait analysis in Uner Tan syndrome cases with key symptoms of quadrupedal locomotion, mental impairment and dysarthric or no speech. NA 9 Sanjoy Sanyal Associate Dean, Clinical Neuroscience Professor, Texila American University, Lot A, Rupert Craig Highway, Goedverwagting, East Coast Demerara, Guyana Peer-review of Gait Analysis in Uner Tan Syndrome Cases Uner Tan himself being a evolutionary biologist, he focussed more on comparative analysis of primates and humans and UTS cases.Â  Â  From a Neuroscience perspective a comparison of the brain scans of these subjects would have been more informative. 8