Re: Human, chimp lineages interbred after splitting, study suggests

94% or 99%?... or less or more? There seems to be little agreement
even among experts in the field.

http://www.chinapost.com.tw/news/archives/taiwan/20061222/98129.htm
Chimpanzee gene study may help find cures for human diseases

2006/12/22
TAIPEI, CNA


The results of a recent analysis of chimpanzee genes may be helpful in developing cures for hepatitis B and C, as well as acquired immunodeficiency syndrome (AIDS) and Alzheimer's disease, sources at Taiwan's National Health Research Institutes (NHRI) said yesterday.

The research paper was published online in November by the scientific journal Genome Research.

The principal author, Chen Feng-chi, an assistant researcher in NHRI's Division of Biostatistics and Bioinformatics, said that humans and chimpanzees are closely related to each other genetically and have 99 percent of genes in common. However, some diseases that are extremely dangerous to humans have altogether no effect on chimpanzees -- and that one percent variance may hold the key to answering such a difference.

For instance, life-threatening complications in the later stages of hepatitis B and C are common in human patients. However, such symptoms never occur in chimpanzees.

The human immunodeficiency (HIV) often leads to AIDS in humans, while there are only a few cases in which HIV in chimpanzees develops into AIDS. And chimpanzees never get Alzheimer's disease, even in old age.

After close comparisons were made between humans and chimpanzees on 7,000 genes related to biological functions, the team found that humans have an additional 840,000 gene deletions and insertions in genetic sequencing, which may lead to the development of the diseases.

Gene deletions and insertions are very similar in the analogy of a word, for example "vocabulary, " that is spelt correctly as "vocabulary"in the chimpanzee genetic sequence,but spelt "vocbulary" or "vocaebulary" in humans, Chen explained.

Chen noted these deletions and insertions may alter the expression of genes and interfere with the functions of RNA and protein, thus creating an environment in which certain human-specific diseases develop.

If a single or a series of deletions and insertions are proved to be related to certain diseases such as hepatitis B/C, AIDS, or Alzheimer's disease, then modifying these alterations may "close the door" and stop the disease from developing, Chen said.
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