A 1-year-old girl with an inborn error of metabolism resulting in a lysosomal storage disease receives a hematopoietic stem cell transplant intended to replace her macrophage population. The gene of interest has a "marker" small nucleotide polymorphism within a non-coding intron of the affected gene in which an A (patient gene) is substituted for a G (donor gene). She does quite well for the first 3 weeks. She tests positive for the missing enzyme, her previously abnormally enlarged organs begin to diminish in size, and assay of peripheral blood lymphocytes reveals increasing numbers of cells with the G polymorphism. However, the attending physicians are now concerned because repeated genetic testing reveals a progressive increase in lymphocytes with the A nucleotide polymorphism. Which of the following is the best explanation for this finding?
The answer is D Rejection of the stem cell transplant is occurring It is evident by reappearance of the marker for the patient's original gene. Small nucleotide polymorphisms are the most frequent form of DNA variation. They are typically small in size, often a single nucleotide. They may occur in any poion of the gene, even in intergenic regions of the genome, and are of increasing impoance as genetic markers.
Generalized immune complex formation
Graft-versus-host disease
Immune paralysis
Rejection of the stem cell transplant
Organ Transplant / Graft