When DNA test says you’re younger man, live 5,000 miles away

Antelope Valley Press (Sunday) - - News - By HEATHER MUR­PHY New York Times

Three months af­ter his bone mar­row trans­plant, Chris Long of Reno, Ne­vada, learned that the DNA in his blood had changed. It had all been re­placed by the DNA of his donor, a Ger­man man he had ex­changed just a hand­ful of mes­sages with.

He’d been en­cour­aged to test his blood by a col­league at the Sher­iff ’s Of­fice, where he worked. She had an inkling this might hap­pen. It’s the goal of the pro­ce­dure, af­ter all: Weak blood is re­placed by healthy blood, and with it, the DNA it con­tains.

But four years af­ter his life­sav­ing pro­ce­dure, it was not only Long’s blood that was af­fected. Swabs of his lips and cheeks con­tained his DNA — but also that of his donor. Even more sur­pris­ing to Long and other col­leagues at the crime lab, all of the DNA in his se­men be­longed to his donor. “I thought that it was pretty in­cred­i­ble that I can dis­ap­pear and some­one else can ap­pear,” he said.

Long had be­come a chimera, the tech­ni­cal term for the rare per­son with two sets of DNA. The word takes its name from a fire-breath­ing crea­ture in Greek mythol­ogy com­posed of lion, goat and ser­pent parts. Doc­tors and foren­sic sci­en­tists have long known that cer­tain med­i­cal pro­ce­dures turn peo­ple into chimeras, but where ex­actly a donor’s DNA shows up — be­yond blood — has rarely been stud­ied with crim­i­nal ap­pli­ca­tions in mind.

Tens of thou­sands of peo­ple get bone mar­row trans­plants ev­ery year for blood can­cers and other blood dis­eases in­clud­ing leukemia, lym­phoma and sickle cell ane­mia. Although it’s un­likely that any of them would end up as the per­pe­tra­tor or vic­tim of a crime, the idea that they could in­trigued Long’s col­leagues at the Washoe County Sher­iff ’s Depart­ment, who have been us­ing their (to­tally in­no­cent) col­league in IT as a bit of a hu­man guinea pig.

The im­pli­ca­tions of Long’s case, which was pre­sented at an in­ter­na­tional foren­sic sci­ence con­fer­ence in Septem­ber, have now cap­tured the in­ter­est of DNA an­a­lysts far be­yond Ne­vada.

The av­er­age doc­tor does not need to know where a donor’s DNA will present it­self within a pa­tient. That’s be­cause this type of chimerism is not likely to be harm­ful. Nor should it change a per­son. “Their brain and their per­son­al­ity should re­main the same,” said Dr. Andrew Rez­vani, med­i­cal direc­tor of the in­pa­tient Blood & Mar­row Trans­plant Unit at Stan­ford Univer­sity Med­i­cal Cen­ter.

He added that pa­tients also some­times ask him what it means for a man to have a woman’s chro­mo­somes in their blood­stream or vice versa. “It doesn’t mat­ter,” he said.

But for a foren­sic sci­en­tist, it’s a dif­fer­ent story. The as­sump­tion among crim­i­nal in­ves­ti­ga­tors as they gather DNA ev­i­dence from a crime scene is that each vic­tim and each per­pe­tra­tor leaves be­hind a sin­gle iden­ti­fy­ing code — not two, in­clud­ing that of a fel­low who is 10 years younger and lives thou­sands of miles away. And so Re­nee Romero, who ran the crime lab at the Washoe County Sher­iff’s Of­fice, saw an op­por­tu­nity when her friend and col­league told her that his doc­tor had found a suit­able match on a donor web­site and he would be un­der­go­ing a bone mar­row trans­plant.

“We need to swab the heck out of you be­fore you have this pro­ce­dure to see how this DNA takes over your body,” she re­called telling him.

Long agreed. He wel­comed an in­trigu­ing dis­trac­tion from his di­ag­no­sis of acute myeloid leukemia and myelodys­plas­tic syn­dromes, both of which im­pair the pro­duc­tion of healthy blood cells.

At the time, he said, “I didn’t even know if I would live.”

Four years later, with Long in re­mis­sion and back at work, Romero’s ex­per­i­ment per­sisted, aided by her crime lab col­leagues. Within four months of the pro­ce­dure, Long’s blood had been re­placed by his donor’s blood. Swabs col­lected from his lip, cheek and tongue showed that these also con­tained his donor’s DNA, with the per­cent­ages ris­ing and fall­ing over the years. Of the sam­ples col­lected, only his chest and head hair were un­af­fected. The most un­ex­pected part was that four years af­ter the pro­ce­dure, the DNA in his se­men had been en­tirely re­placed by his donor’s.

“We were kind of shocked that Chris was no longer present at all,” said Darby Stien­metz, a crim­i­nal­ist at the Washoe County Sher­iff ’s Of­fice.

If an­other pa­tient re­sponded sim­i­larly to a trans­plant and that per­son went on to com­mit a crime, it could mis­lead in­ves­ti­ga­tors, said Brit­tney Chilton, a crim­i­nal­ist at the Sher­iff’s Of­fice foren­sic sci­ence divi­sion.

And it has mis­led them, Chilton learned once she be­gan to re­search chimerism. In 2004, in­ves­ti­ga­tors in Alaska up­loaded a DNA pro­file ex­tracted from se­men to a crim­i­nal DNA data­base. It matched a po­ten­tial sus­pect. But there was a prob­lem: The man had been in prison at the time of the as­sault. It turned out that he had re­ceived a bone mar­row trans­plant. The donor, his brother, was even­tu­ally con­victed.

The specifics of Long’s sit­u­a­tion raise an in­evitable ques­tion: What hap­pens if he has a baby? Would he pass on the genes of his Ger­man donor or his own to fu­ture off­spring? In this case, the an­swer will re­main untested be­cause Long had a va­sec­tomy af­ter his sec­ond child was born.

But what about ev­ery­one else? Three bone mar­row trans­plant ex­perts who were sur­veyed agreed that it was an in­trigu­ing ques­tion. They also agreed that pass­ing on some­one else’s genes as a re­sult of a trans­plant like Long’s was im­pos­si­ble.

“There shouldn’t be any way for some­one to fa­ther some­one else’s child,” said Rez­vani, the Stan­ford med­i­cal direc­tor.

That’s not to say that other forms of chimerism haven’t cre­ated com­pa­ra­bly con­fus­ing sce­nar­ios. Fra­ter­nal twins some­times ac­quire each other’s DNA in the womb; in at least one case, that led to un­founded fears of in­fi­delity when a man’s child did not seem to be his. In an­other case, a mother nearly lost cus­tody of her chil­dren af­ter a DNA test.

But a donor’s blood cells should not be able to cre­ate new sperm cells, Rez­vani said. Dr. Mehrdad Abedi, the doc­tor at the Univer­sity of Cal­i­for­nia, Davis, who treated Long, agreed; he be­lieved it was Long’s va­sec­tomy that ex­plained how his se­men came to con­tain his donor’s DNA. The foren­sic sci­en­tists in­volved said they plan to in­ves­ti­gate fur­ther.

New York Times

Chris Long at the Washoe County Sher­iff’s Of­fice in Reno, Nev., agreed to serve as a guinea pig for his col­leagues’ ex­per­i­ment to help them un­der­stand how a bone mar­row trans­plant could con­fuse a crim­i­nal in­ves­ti­ga­tion.

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