Pathology Single Gene Disorders 23f0133c List the odd one out among the following A Trisomy 18 (Noonan syndrome) B Trisomy 21 (Downs syndrome) C Trisomy 18 (Edwards synd.) D Trisomy 13 (Patau synd.) High-Yield Explanation Trisomy 18 is Edward syndrome & not Noonan syndrome. Noonan syndrome occurs in both males and females with a normal karyotype(46,XX and 46,XY). Refer to the image below.