There is also a CCR5 gene mutation that some HIV+ people have that can confer immunity because the defect keeps HIV from entering cells. Heterozygous carriers of same gene mutation can experience a much slower progression of the disease. The youngest son of Paul and Elizabeth Glaser is HIV+, in his 20s and is symptom free.
The gene that codes for CCR5 is situated on human chromosome 3. Various mutations of the CCR5 gene are known that result in damage to the expressed receptor. One of the mutant forms of the gene is CCR5-delta32, which results from deletion of a particular sequence of 32 base-pairs. This mutant form of the gene results in a receptor so damaged that it no longer functions. But surprisingly, this does not appear to be harmful:
Photo wikipedia.org
Bacteria carried by fleas
Yersinia pestis seen at 2000x magnification. This bacterium, carried and spread by fleas, is generally thought to have been the cause of millions of deaths.
‘It’s highly unusual,’ says Dr. Stephen J. O’Brien of the National Institutes of Health in Washington D.C. ‘Most genes, if you knock them out, cause serious diseases like cystic fibrosis or sickle cell anemia or diabetes. But CCR5-delta32 is rather innocuous to its carriers. The reason seems to be that the normal function of CCR5 is redundant in our genes; that several other genes can perform the same function.’
http://creation.com/ccr5delta32-a-very-beneficial-mutation
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