25 January 1998

Hi, I am trying to seek clarification/perspectives on a set of disorders I have come across whilst looking for genetic disorder mapping to human 12q. Noonan syndrome has been mapped to 12q (Jamieson 1994, Nat.Genet. 8:357-360, but scouring through literature I have come across reports that suggest Noonan syndrome shares characteristics with Cardio-Facio-Cutaneous syndrome and LEOPARD syndrome, and some or all of these may represent manifestations of the same entity.
Are there any views out there on this point. Also is there any evidence that any or all of these may be contiguos gene disorders caused by deletions taking out several genes, or conversely that these are single gene defects?

Thanks for your help.