Phenotypical manifestations of partial trisomy 9 and monosomy 4 in two siblings.

In this case report, we describe two siblings with a previously unreported partial monosomy 4q and partial trisomy 9q. The sibling karyotypes were determined to be 46,XX,der(4)t(4;9)(q33;q33)pat and 46,XY,der(4)t(4;9)-(q33;q33)pat. The siblings share several common pathological features, including VSD, PDA, low-set ears and digit anomalies as well as features consistent with Pierre-Robin syndrome and hydrocephalus. We review previously reported phenotypes associated with monosomy 4q and partial trisomy 9q and discuss potential mechanisms for these morphological insults with particular emphasis on neuropathology.