We have identified inherited mutations in genes of the telomere repair complex in patients with acquired aplastic anemia. These mutations diminish the ability of cells to repair the ends of chromosomes, called telomeres, which normally shorten with each cell division. Mutations in TERC, the gene which encodes for the RNA template of the complex; in TERT, the gene for the enzyme in the complex, and also in the Schwachman-Bodian-Diamond syndrome gene (SBDS), which we believe to be associated with telomere repair, lead to reduced telomerase activity, diminished numbers of hematopoietic cells in the bone marrow, and presumably also a deficiency in the ability of cells to respond to immunological attack and destruction of the hematopoietic system.

This laboratory research protocol will allow us to evaluate whether similar gene mutations might underlie other autoimmune diseases, here specifically, inflammatory bowel disease, which share broad pathophysiologic features with immune-mediated aplastic anemia. We will directly assess by DNA sequencing suspect genes (TERC, TERT, SBDS, DNA helicases and others) in buccal mucosal samples obtained from patients with inflammatory bowel disease (IBD).

Analyses from large numbers of controls have defined polymorphisms for these genes. IBD samples will allow us to determine whether mutations in these genes are more prevalent in this patient population and to test the hypotheses that telomere repair defects underlie human autoimmunity, or that these genes are specifically involved in hematology as risks factors for bone marrow failure.