code: def __set_lost_start_status(self, hgvs_string):
          
          # set is lost start status
          mymatch = re.search('^([A-Z?])(\d+)([A-Z?])$', hgvs_string)
          if mymatch:
              grps = mymatch.groups()
              if int(grps[1]) == 1 and grps[0] != grps[2]:
                  self.is_lost_start = True
                  self.is_non_silent = True
              else:
                  self.is_lost_start = False
          else:
              self.is_lost_start = False
docs: Sets the self.is_lost_start flag.