Final answer:
Yes, it is possible to have more than one DR beta gene in the HLA system.
Step-by-step explanation:
Yes, it is possible to have more than one DR beta gene. In the human leukocyte antigen (HLA) system, the HLA-DR locus contains multiple alleles that can be combined to form different DR beta genes. The HLA-DR genes are involved in the immune response and play a role in determining compatibility between donors and recipients for organ transplantation.