A 50-year-old previously healthy man is evaluated for progressive fatigue, weakness, and recurrent gingival bleeding. Laboratory studies reveal normocytic normochromic anemia, thrombocytopenia, and leukocytosis with circulating myeloblasts. Bone marrow biopsy establishes a diagnosis of acute myeloid leukemia. Induction chemotherapy followed by allogeneic hematopoietic cell transplantation (HCT) is planned. Molecular typing of human leukocyte antigen (HL A) -A, -B, -C, -DP, -DQ, and -DR is performed. The patient's biological sister, with whom he shares both parents, is eligible for stem cell donation and undergoes HLA typing. Which of the following is the most likely probability that the sibling will be an identical HLA match with this patient?

Question

A 50-year-old previously healthy man is evaluated for progressive fatigue, weakness, and recurrent gingival bleeding.  Laboratory studies reveal normocytic normochromic anemia, thrombocytopenia, and leukocytosis with circulating myeloblasts.  Bone marrow biopsy establishes a diagnosis of acute myeloid leukemia.  Induction chemotherapy followed by allogeneic hematopoietic cell transplantation (HCT) is planned.  Molecular typing of human leukocyte antigen (HL A) -A, -B, -C, -DP, -DQ, and -DR is performed.  The patient's biological sister, with whom he shares both parents, is eligible for stem cell donation and undergoes HLA typing.  Which of the following is the most likely probability that the sibling will be an identical HLA match with this patient?

Quizplus · Accepted Answer

Eductional Objective: The human leukocyte antigen (HLA) genes encode major histocompatibility complex (MHC) molecules that are key to activation of the immune system in response to foreign (non-self) antigens.  All the HLA genes are clustered together, meaning that there is a low rate of crossover and that offspring essentially inherit 2 HLA haplotypes, one from each parent.  Therefore, the probability that a sibling would be an identical HLA match is 1/4.

A 50-Year-Old Previously Healthy Man Is Evaluated for Progressive Fatigue