<prompt> Answer this question truthfullyWhat does Imerslund-Grasbeck syndrome mean?  <response>: <reason> Imerslund-Grasbeck syndrome or Imerslund-Najman-Grasbeck syndrome or Imerslund-Grasbeck disease IGS or INGS is an autosomal recessive, familial form of vitamin B 12 deficiency caused by malfunction of the receptor located in the terminal ileum. 