57317 IMGP3203

«Nijmegen syndrome

• Cytogcnctic anulysis a Ilon s dctcction orchromo*omal fnslability, which is a

chnractcrisiic fealurc orthc discasc, although Uie poor response of'I lymphocyles (o mitpgćnś can ollcn make diugnosis diniculL

• In generał, Uie conslilutional kuryotypcs of paticnU wilh .NBS arc normuj (4<vY\ or 4UII) Howcver, in u high proporlion of phytohcmagglutinui CPHAJ-slimulatcd lymphocyles (10-60%), sponluncous slructurul chromosomal rearrungements arc oburreu, as w cli as ouier abcrralions such as chrpmutid and/or chromosomc hreaks and aeenlric fragmcnls.

•    Mosl of thcsc rearrangements speciflcally involvc chromosomcs 7 and 14,

wilh breakpolnts at bands 7pl3, 7q35, 14ql I, and 14q32, which are idenlical to those found in AT.

ImrounoglobuJin chain and T-cdl receptor genes arc localcd at thcsc silos.

I be mosl ircqucntly and conslanlly detcclcd uberrulion is inv(7)(nl3c|35). fnllnn cd SŚ translocalions 7/14, 7/7, and 14/14.