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                         January 3, 2024

       Christopher Hall
       President and Chief Executive Officer
       Personalis, Inc.
       6600 Dumbarton Circle
       Fremont, California, 94555

                                                        Re: Personalis, Inc.
                                                            Registration 
Statement on Form S-3
                                                            Filed December 21, 
2023
                                                            File No. 333-276204

       Dear Christopher Hall:

              This is to advise you that we have not reviewed and will not 
review your registration
       statement.

               Please refer to Rules 460 and 461 regarding requests for 
acceleration. We remind you
       that the company and its management are responsible for the accuracy and 
adequacy of their
       disclosures, notwithstanding any review, comments, action or absence of 
action by the staff.

                                                        Please contact Conlon 
Danberg at 202-551-4466 with any questions.



                                                                                
                         Sincerely,

                                                                                
                         Division of Corporation Finance
                                                                                
                         Office of Industrial Applications and
                                                                                
                         Services
       cc:                                              Asa M. Henin, Esq.