PTC Therapeutics Inc., a South Plainfield, N.J.-based drug company focused on post-transcriptional control mechanisms, has withdrawn its $86.25 million IPO filing, citing “market conditions.” The company had originally filed in March 2006, with Morgan Stanley and JPMorgan serving as lead underwriters. PTC has raised over $143 million in total VC funding since its 1998 inception, including a $10 million Series F round earlier this year (according to a regulatory filing). Backers include CSFB Private Equity, HBM BioVentures, Vulcan Ventures, Novo A/S, Delphi Ventures, Bay City Capital, Novartis BioVentures, Amgen Ventures and HealthCap.