A 4 MB CRYPTIC DELETION ASSOCIATED WITH INV(8)(Q13.1Q24.11) IN A PATIENT WITH TRICHORHINOPHALANGEAL SYNDROME TYPE-I

We report on an 11 year old girl with trichorhinophalangeal syndrome t ype I (TRPS1), postaxial polydactyly of the fingers, and a de novo par acentric inversion on the long arm of chromosome 8 involving bands q13 .1 and q24.11. Molecular analysis using FISH and polymorphic DNA marke rs detected an approximately 4 Mb, cytogenetically unidentified deleti on occurring between two STSs markers, AFMB331YA9 and D8S1200, around the region of the distal inversion breakpoint. Although the deletion i s large, mental retardation was not present in the patient. This is th e first report of a cryptic deletion in a TRPS1 patient, both ends of which were analysed at the molecular level. The data obtained are usef ul for defining the location of the putative mental retardation gene(s ) in TRPS1 and Langer-Giedion syndrome (TRPS2), as well as a locus for postaxial polydactyly.