Basilar artery dolichoectasia in a boy with a combination of partial monosomy 18p and partial trisomy 20q.

We describe an 11-year-old boy with facial dysmorphism consisting of a round and flat face, hypertelorism, short nose, and down turned corners of the mouth. In addition, he had severe mental retardation, short stature, imperforate anus, and basilar artery dolichoectasia. Cytogenetic evaluation revealed an unbalanced paternally inherited translocation t(18;20)(p11.2q13.3), resulting in partial monosomy 18p and partial trisomy 20q. The combination of deletion 18pduplication 20q has not been previously described and we suggest that the unusual finding of basilar artery dolichoectasia may be a feature of one of the imbalances.