Reply to Hedrick and Klitz: High haplotype discovery rate in the HLA locus

We have recently shown in 2 large-scale surveys (1, 2) that human leukocyte antigen (HLA) haplotypes frequency distributions are better characterized by purifying selection than by balancing selection. In their Letter, Hedrick and Klitz claim that the HLA locus is a classical example of balancing selection and that our recent results contradict this traditional view (3). They criticize 3 main aspects of our analyses: [↵][1]1To whom correspondence may be addressed. Email: koonin{at}ncbi.nlm.nih.gov or louzouy{at}math.biu.ac.il. [1]: #xref-corresp-1-1