Set the ball rolling

   I don't understand what "The difference sets the ball rolling and a million other things

downstream go wrong" means.  Does it mean "the difference serves as a troublemaker, and then once the trouble gets started,  a lot of things that follow will go wrong"?

  Context:

His team showed that mice without a gene that makes a compound broken-down from oestrogen called 2-methoxyestradiol (2-ME) develop many of the signs of pre-eclampsia, including pre-term birth, high blood pressure and problems forming blood vessels.
 
"The difference sets the ball rolling and a million other things downstream go wrong," Kalluri says.

   More context see the article:
  http://www.newscientist.com/article/dn13865-treatment-hope-for-killer-pregnancy-condition.html?DCMP=ILC-hmts&nsref=news1_head_dn13865

NL888

Does it mean "the difference serves as a troublemaker, and then once the trouble gets started,  a lot of things that follow will go wrong"?

Yup!  That's what it means.  The difference -- or rather, the abnormality -- is the source of all the trouble.  It sets a series of causes and effects into motion.  If you trace the original cause to its effect, then that cause to its effect, and so on, (moving "downstream"), you see that lots of things go wrong because the first thing went wrong.

CJ