In a family HLA typing for stem cell donation, what is the expected B antigen in the third child given the parents' typings?

The answer suggests that the expected B antigen in the third child is B35. In HLA typing for stem cell donation, the inheritance of HLA antigens follows a Mendelian pattern, where each child inherits one set of alleles from each parent.

To arrive at the expected B antigen, both parents' HLA types are considered. Each parent contributes one of their HLA alleles for the B locus. If, during the testing or given information, one or both parents have the B35 antigen present in their HLA typing, there would be a chance that the third child could inherit this antigen. The selection for B35 as the answer indicates that the antigen is common among the parents.

Understanding that HLA typification involves multiple alleles allows us to see why B35 is the anticipated antigen for the third child if it is a possibility in the parents’ markers. This ties into the framework of how offspring inherit a combination of genes from both parents, and in this case, the presence of the B35 antigen is significant for compatibility in stem cell donation.

In family HLA typing, family members must match closely for successful transplantation, making the identification of specific antigens vital. The B antigen chosen must be one that is manifested in