Objective We present a 5-year old girl with mild developmental delay, short stature, stigmata dysplastica and strabism, who developed typically up to seventh month when growth and motor development slowed down. Year later squint was observed. At four years social functioning disorder was diagnosed, mainly due to speech delay. Laboratory and imaging results were not informative. General impression following the Gestalt principle led us to closer observation of a girl. Observation, documentation and assessment tool for babies' development was initiated by prof. Prechtl who described spontaneous movement, now called general movement (GM) in term babies and discovered that the quality of spontaneous general movements in the foetus and young infant could provide information on the integrity of the young nervous system. We have decided to use modified approach to the qualitative assessment of movements in our patient. Methods Short footage of girl's movement in our ambulatory unit showed discrete dystonic movements, which were not identified previously as well as inequivalent body scheme. The girl was sent for sensory-motor integration as well as further genetic work-up: kariotyping and FISH analysis. Results Filming enabled us to identify dystonia. Kariotyping showed two cell lines: 93% of all analysed cells showed isochromosome 18 (46,XX, i(18)(q10)); 7% of cells had 18p deletions (46,XX, del(18)(p11.1)). Kariotypes of both parents were normal. In both cell lines monosomy of short arm as well as trisomy of long arm of chromosome 18 were present. Dystonia is described as a rare feature of monosomy 18p. Conclusion In the presenting case, analysis of movement by filming revealed dystonia, which further guided diagnostic testing and treatment. By following consesus 2013 regarding dystonia we found a rare mutation which would not be detected otherwise. We present a 5-year old girl with mild developmental delay, short stature, stigmata dysplastica and strabism, who developed typically up to seventh month when growth and motor development slowed down. Year later squint was observed. At four years social functioning disorder was diagnosed, mainly due to speech delay. Laboratory and imaging results were not informative. General impression following the Gestalt principle led us to closer observation of a girl. Observation, documentation and assessment tool for babies' development was initiated by prof. Prechtl who described spontaneous movement, now called general movement (GM) in term babies and discovered that the quality of spontaneous general movements in the foetus and young infant could provide information on the integrity of the young nervous system. We have decided to use modified approach to the qualitative assessment of movements in our patient. Short footage of girl's movement in our ambulatory unit showed discrete dystonic movements, which were not identified previously as well as inequivalent body scheme. The girl was sent for sensory-motor integration as well as further genetic work-up: kariotyping and FISH analysis. Filming enabled us to identify dystonia. Kariotyping showed two cell lines: 93% of all analysed cells showed isochromosome 18 (46,XX, i(18)(q10)); 7% of cells had 18p deletions (46,XX, del(18)(p11.1)). Kariotypes of both parents were normal. In both cell lines monosomy of short arm as well as trisomy of long arm of chromosome 18 were present. Dystonia is described as a rare feature of monosomy 18p. In the presenting case, analysis of movement by filming revealed dystonia, which further guided diagnostic testing and treatment. By following consesus 2013 regarding dystonia we found a rare mutation which would not be detected otherwise.