The present study focussed on a specific type of rare genetic condition: chromosome 14 deletions. Children with this genetic condition often show developmental delays and brain and neurological problems, although the type and severity of symptoms varies depending on the size and location of the deleted genetic material. The specific aim of the present study was to describe the developmental trajectories of language skills in a group of children with linear 14q deletions. Four children with an interstitial deletion of the long arm of chromosome 14 were followed for 1 year. Data collected from psychomotor and linguistic assessments highlight a large individual variability. Considering the children's genetic and clinical conditions, findings revealed that the size of the deleted area is not related to outcome. However, the developmental trajectories of language development are deeply influenced by the presence of clinical conditions, such as autism spectrum disorders. (Contains 2 tables and 5 figures.)