SecProbe.io

May 23, 2013

Via E -mail
Stuart M. Peltz, Ph.D.
Chief Executive Officer
PTC Therapeutics, Inc.
100 Corporate Court
South Plainfield, NJ  07080

Re: PTC Therapeutics, Inc.
Registration Statement on Form S -1
Filed May 16, 2013
  File No. 333 -188657

Dear Dr. Peltz:

We have reviewed your registration statement and letter submitted May 16, 2013, and
have  the following comments.  In some of our comments, we may ask you to provide us with
information so we may better understand your disclosure.

Please respond to this letter by amending your registration statement and providing the
requested information.   If you do not believe our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.

After reviewing any amendment to your registration statement and the information you
provide in r esponse to these comments, we may have additional comments.

Unaudited Financial Statements March 31, 2013
Notes to Unaudited Financial Statements

2. Summary of Significant Accounting Policies
Basis of Presentation, page F -33

1. Please tell us the reason  for including the statement “The December 31, 2012  balance
sheet was derived from audited financial statements, but does not include  all disclosures
required by U.S. generally accepted accounting principles” in your  disclosure.

Stuart W. Peltz, Ph.D.
PTC Therapeutics, Inc.
May 23, 2013
Page 2

 5. Capital Structure, page F -37

2. Please describe how you allocated the proceeds of the convertible promissory  notes
between the debt and the warrant liability. Reference for us the  authoritative literature
you relied upon to support your accounting. Quantify and  discuss any significant
assumptions underlying your allocation.

3. You disclose that since the value of the warrants exceeded the proceeds from the
convertible notes it was considered a deemed dividend and was reflected as an  equity
transaction in your financial stateme nts. Please reference for us the  authoritative literature
you relied upon to support your presentation of the deemed  dividend in your statements
of operations.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Act of 1933 and
all applicable Securities Act rules require.   Since the company and its management are in
possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.

Notwithstanding our comments, in the event you request acceleration of the effective date
of the pending registration statement please provide a written statement from the company
acknowledging that:

 should the Commission or the staff, acting pursuant to delegated authority, declare the
filing effective, it does not foreclose the Commissi on from taking any action with respect
to the filing;

 the action of the Commission or the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not relieve the company from its full responsibility for
the adequacy and acc uracy of the disclosure in the filing; and

 the company may not assert staff comments and the declaration of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the federal
securities laws of the United States.

Please refer to Rules 460 and 461 regarding requests for acceleration.  We will consider a
written request for acceleration of the effective date of the registration statement as confirmation
of the fact that those requesting acceleration are aware of their  respective responsibilities under
the Securities Act of 1933 and the Securities Exchange Act of 1934 as they relate to the proposed
public offering of the securities specified in the above registration statement.  Please allow
adequate time for us to revi ew any amendment prior to the requested effective date of the
registration statement.

Stuart W. Peltz, Ph.D.
PTC Therapeutics, Inc.
May 23, 2013
Page 3

 You may contact Ibolya Ignat, Staff Accountant, at (202) 551 -3656 or Gus Rodriguez,
Accounting Branch Chief, at (202) 551 -3752 if you have questions regarding comme nts on the
financial statements and related matters.  Please contact Karen Ubell, Staff Attorney, at (202)
551-3873, Dan Greenspan, Legal Branch Chief, at (202) 551 -3623 or me at (202) 551 -3715 with
any other questions.

Sincerely,

 /s/ Daniel  Greenspan  for

Jeffrey P. Riedler
Assistant Director

cc: Via E -mail
 Clark W. Petschek
Wilmer Cutler Pickering Hale and Dorr LLP