Comparing mitochondrial DNA from an unidentified mummy to the genetic code of an identified female mummy can establish a family relationship.
But the technique limits researchers to tracing a mummy's lineage through its female bloodline, which may not be available in many cases.
So instead the Egyptian team will examine the male mummy's nuclear DNA, which yields just one copy of the genetic code in each cell but can be traced from either parent.
This exhaustive testing process is made more difficult by contamination of the mummies' DNA over time and from chemicals used in the mummification process.
"[The DNA samples] are not just damaged because they are really old," Corthals said.
"They are also damaged because of the process of mummification. Ironically, what preserves the mummies best for their appearance destroys the DNA."
Several queens of the 18th dynasty, which lasted from 1550 to 1069 B.C. and preceded Tutankhamun's reign, have yet to be identified.
These include Kiya, who was likely Tut's mother and thus would share his mitochondrial DNA.
(Related photos: "Who Was King Tut's Father?" [July 10, 2007].)
The queens Nefertiti, Tut's father's primary wife, and Tiye, Tut's paternal grandmother, have also not been found.
Scientists will study the male mummy on a hunch that it belongs to Thutmose I, who ruled from 1504 to 1492 B.C. and was the father of Queen Hatshepsut.
A mummy on display in the Egyptian Museum is labeled as Thutmose I, but recent tests revealed that the body is misidentified, Hawass noted.
"We found the mummy in the museum died at the age of 30, and Thutmose I died at the age of 50," he said. "He is not a royal mummy."
In 2007 Corthals and the Egyptian scientists conducted tests on a female mummy that is believed to be that of Hatshepsut.
The scientists will compare DNA from that mummy to the one recently found, but they note that making a connection will be hard because Thutmose I's family line is dubious.
His father is unknown and his mother was called Seniseneb, which was a common name during her time.
Inscriptions indicate that Thutmose I married his sister Ahmose, who was likely named after the first pharaoh of the 18th dynasty. But her exact parentage is also in doubt.
"It's not always clear who's in the family tree," Corthals said. "You may be testing who you think is the mother, but it might not be the mother at all."
In general, Corthals added, results from testing ancient DNA are not always certain.
"In the best of cases you can be only sure of a maximum if you are really lucky of 90 percent [with mitochondrial DNA], but that's about it," Corthals said.
"There are to date no published studies that have successfully retrieved and compared ancient nuclear DNA from Egyptian mummies for the purpose of interfamily lineage."
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