Several authors have attempted to characterize the partial 1q trisomy syndrome, reporting clinical features such as mental retardation, macrocephaly, large fontanels, prominent forehead, broad flat nasal bridge, high-arched palate, micro/retrognathia, low-set ears, and cardiac defects. However, defining the partial trisomy 1q syndrome is difficult, because it is a rare chromosomal abnormality and in most instances the trisomy 1q is combined with partial monosomy of another autosomal segment. We report on the clinical and molecular cytogenetic study of a patient who presents pure partial 1q duplication. This is the first case of pure duplication 1q41-qter in the literature. © 2008 Wiley-Liss, Inc.