Molecular cytogenetic characterization of a derivative chromosome 8 with an inverted duplication of 8p21.3-->p23.3 and a rearranged duplication of 8q24.13-->qter.

A derivative chromosome 8 was observed in a newborn boy who presented with low birth weight, multiple congenital anomalies, and dysmorphic face. The der(8) was further characterized at age 18 months by a high resolution G-banding analysis, spectral karyotyping, and fluorescence in situ hybridization (FISH) with multiple DNA probes. The karyotype was described as 46,XY,der(8)(qter-->q24.13::p21.3-->p23.3::p23.3-->qter), representing an inverted duplication of region 8p21.3-->p23.3 and a duplication of region 8q24.13-->qter, which attaches to the duplicated short arm segment at 8p21.3. Different from previously reported patients with an inverted duplication (8p), no deletion was detected in the distal region of 8p in this case. This young child had manifested a broad nasal bridge, micrognathia, cleft lip, hydrocephalus, partial agenesis of the corpus callosum, Dandy-Walker malformation, congenital heart defects, dysplastic kidneys, hydronephrosis, marked hypotonia, and significant psychomotor retardation. These features are compared with those commonly seen in cases with an inverted duplication of 8p and cases with a partial trisomy of 8q.