Cobalamin Malabsorption or Imerslund-Grasbeck Syndrome (IGS) is an inability of the intestine to properly absorb B12 which is needed for cell growth and in the nervous system. Early signs include a loss of appetite and energy, and abnormal growth.
Imerslund-Grasbeck Syndrome is an autosomal recessive condition caused by a mutation in the CUBN gene.