Genetic Q 12 with explanation - aquatic_horizon

[ArchivalUser]

that's why i posted this!!! http://www.usmleforum.com/showthread.php?tid=414951

[ArchivalUser]

THANK U SO MUCH SAMO
link is very helpfull

[ArchivalUser]

Why chance of two siblings being HLA-identical is 1/4?


1-The best potential for an HLA match is within the family. Each person inherits one A, B, C, DR and DQ antigen from each parent. Thus, we have two HLA-A antigens, two HLA-B antigens and so on.

2-The number of different HLA combinations is limited to the HLA types of the parents.

3-The combination of HLA-A, B, DR and DQ antigens inherited from each parent is called a haplotype.

4-Each parent has two HLA haplotypes one of which will be inherited by each child.

5-For all children sharing the same parents, there will only be four possible combinations of HLA antigens or haplotypes.

6-The odds of finding œmatches between siblings greatly increases compared to the general population because we have a 1-in-4 chance of being identical to each sibling.