Jacobsen syndrome (JS) is a contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11. The syndrome is rare and there are very few observations regarding the pubertal period of the affected individuals. We report the case of a 22-year-old female, with JS, monitored since the age of three months. She presented intrauterine growth retardation, failure to thrive and feeding difficulties from the first year of the life, and she learned to walk at the age of four years. Phenotypically, the case is characterized by distinctive facial and limb abnormalities. She shows spasticity and profound delay in gross and fine motor skills. Additionally, she has severe learning difficulties, non-verbally communicates, and displays hetero-aggressive and auto-aggressive behavior. The evolution of puberty was characterized by hypogenitalism and primary amenorrhea. Thrombocytopenia and IgM deficiency became apparent also at puberty. Array comparative genomic hybridization (aCGH) analysis confirmed a deletion of 16.3 Mb on 11q23.3-q23.4. We report this case as the first documented case of JS in Romania, as well as for clinical particularities (long period of survival and late appearance of hematological and immunological disorders).