A t(5;16)(p15.32;q23.3) generating 16q23.3 --> qter duplication and 5p15.32 --> pter deletion in two siblings with mental retardation, dysmorphic features, and speech delay.

We report on two siblings (half brothers on the paternal side) with a syndrome consisting of delayed development, cardiac anomalies, chest deformity, hip rotation, metatarsus adductus, genital hypoplasia, dysmorphic face, depressed nasal bridge, mental retardation, and speech delay. All metaphases examined showed a normal karyotype in the patients, their father, and both mothers. High-resolution array CGH examination revealed a 16q (6 Mb) duplication dup(16)(16q23.3 --> 16qter) and a 5p (0.97 Mb) terminal deletion del(5)(p15.32 --> pter) in both affected boys but not their healthy siblings or parents. Interphase fluorescence in situ hybridization (FISH) confirmed both the 16q duplicated region and the 5p terminal deletion. Clinical abnormalities in the patients included thin upper lip, clinodactyly, and foot deformity, which were reported previously with duplications in 16q23.3. Pectus excavatum, hip rotation, metatarsus adductus, umbilical hernia, brachycephaly, and esotropia were not reported previously in chromosome 16q duplications but may be features that occur intermittently. The 5p deleted region has been associated previously only with speech delay, which was present in both patients. These patients display certain phenotypic characteristics not reported previously in 16q duplication and confirm 5p terminal deletion as an important chromosome anomaly for speech delay.