FISH and cytogenetic characterization of a terminal chromosome 1q deletion: clinical case report and phenotypic implications.

We report a 24-year-old woman with minor facial anomalies, mental retardation, seizures, and partial agenesis of the corpus callosum. Cytogenetic analysis showed a de novo terminal chromosome 1 long arm deletion. FISH with a panel of chromosome 1q42-qter bands-specific BAC and YAC clones located the breakpoint at the 1q42-q43 junction, with monosomy restricted to the 1q43 and 1q44 bands. The changing craniofacial phenotype of this patient with age is described as part of the del(1)(q) syndrome natural history. The patient's features are compared with those of other patients with similar deletions, and variable phenotypic findings due to different deleted chromosomal segments are discussed.