Eur. J. Med. Gen.

previous termInterstitial deletions and pericentric inversions of chromosome 4next term appear to be unusual phenomena. Here, we report the case of previous termanext term 14-year-old boy with severe psychomotor retardation with previous termanext term de novo 46,XY,der(previous term4)next termdel(p15.2p15.31)inv(previous term4)next term(p15.2q13.3)del(previous term4)next term(q13.2q13.2) karyotype. We used FISH analysis with YAC and BAC clones to characterise the previous terminversion'snext term breakpoints. previous termAnext term complex event with six breakpoints was found, characterised by previous terma pericentric inversion and two deletions,next term the first on the short arm of previous termchromosome 4next term (4p) and the second on the long arm of previous termchromosome 4next term (4q). The previous termdeletionnext term events had removed previous termtwonext term segments, one of approximately 5 Mb, from 4p, outside the previous terminversion,next term and the other 2 Mb from 4q, inside the previous terminversion.next term These rearrangements were not found in the parents. Microsatellite marker analysis showed that the previous terminversionnext term carrying previous termchromosome 4next term was derived from the father. Bioinformatic analysis of the human genome sequence allowed us to identify several hemizygotic genes in the previous termpatient,next term which might be involved in the pathogenesis of this clinical previous termphenotype.next ter