Clinical and molecular cytogenetic characterization of two patients with partial trisomy 1q41-qter: further delineation of partial trisomy 1q syndrome.

We report the clinical and molecular cytogenetic characterization of two patients with partial trisomy 1q. The first patient is a currently 11-year-old female proposita with a de novo unbalanced translocation 46,XX,der(8)(8qter-8p23.3::1q41-1qter), leading to a partial trisomy 1q41-qter and a partial monosomy for 8p23.3-pter. The most prominent clinical features of the girl are a triangular face, almond-shaped eyes, low-set ears, short stature with relatively long legs, and mild psychomotor retardation. To our knowledge, the cytogenetic aberration in this girl is the most proximal partial trisomy 1q leading to a mild phenotype. Recently, we identified a second patient with a similar partial trisomy 1q combined with a cri du chat syndrome caused by a de novo unbalanced translocation 46,XX,der(5)(5qter-5p13.1::1q41-1qter). Comparison of the phenotype of the two girls as well as with already published trisomy 1q cases was performed, and fluorescence in situ hybridization probes from selected YACs were used to delineate the extent of the partial trisomy in more detail.