A How many HLADR combinations can be made by an individual

A. How many HLA-DR : combinations can be made by an individual who is heterozygous at all HLA-DR loci, inherits the DR haplotype DRB1 from their mother, the DR haplotype DRB1, DRB4 from their father, and also inherits different allelic forms of DRA from each parent?

B. Repeat this exercise given the same information except that the maternal DR haplotype is DRB1, DRB3.

Solution

a)In the first case the haplotype DRB1 is taken from mother and DRB1,DRB4 from father

the combinations will be DRB1-DRB1 , DRB1-DRB4, DRB4-DRB1.so the total number of combinations is 3

b)In the second part the number of combinations remain same as instead of DRB4 WE HAVE DRB3

=>DRB1-DRB1,DRB1-DRB3,DRB3-DRB1=>3