DOVER AIR FORCE BASE, Del. – The Armed Forces Medical
Examiner System’s Armed Forces DNA Identification Laboratory briefed families
of missing service members at the Defense POW/MIA Accounting Agency’s latest
family member update in Philadelphia, Pennsylvania, September 8, 2018.
The DPAA conducts periodic and annual government
briefings for families of service members who are missing in action. These
events are designed to keep family members informed of those still missing and
to discuss in detail the latest information available about their specific
case. Nearly 400 families participated in this months’ FMU making it the most
attended FMU since Dallas, Texas, 2012.
DNA analysts from AFMES-AFDIL were on site to collect DNA
samples from family members using a buccal swab, which looks similar to a
The swabs are used to test for mitochondrial DNA and
nuclear DNA. Both of these types of DNA can be utilized for human
identification and forensic testing.
Of those, mtDNA is not unique to an individual, but is
common to an individual’s maternal lineage. Nuclear DNA, where Y- Chromosomal DNA
and auDNA are found, is unique to an individual, with half of the DNA coming
from the mother and half coming from the father.
Y-Chromosomal DNA is passed from father to son thru the
paternal lineage with brothers sharing the same Y-Chromosomal DNA and the Y-Chromosomal
DNA will be passed down to their sons. However, sisters will not have the
Y-Chromosomal DNA and their son’s would have Y-Chromosomal DNA passed from
their son’s father.
“There is only one Y chromosome per cell, compared to
100’s of mitochondria,” said Julie Demarest, AFMES-AFDIL Family Reference
Sample technical leader. “However, in cases where a service member does not
have any living or available mtDNA references, Y-[Chromosome Short Tandem
Repeat markers] testing can provide another avenue for identification, and our
technology has improved to the point that more and more often we are able to
obtain Y-STR information for an unknown sample.”
In 2006, AFMES-AFDIL was able to test for auSTR and
Y-STR, with the first case being utilized in the DPAA mission to identify a
service member missing from the Vietnam War, according to Dr. Timothy McMahon,
Department of Defense DNA Operations director. However, it wasn’t routinely
used until 2010 when AFMES-AFDIL had an increase in family references.
By 2013, AFMES-AFDIL added a Low Copy Number Y-STR
amplification method along with an enhanced DNA purification method.
“This doubled our success rates to 50 percent or
greater,” said McMahon. “Additional processing efficiencies allowed for us to
maintain a 60 percent success rate for Y-STR and auSTR in 2018.”
This has allowed AFMES-AFDIL to increase the likelihood
of identifications of individuals sharing a more common mtDNA sequence or in
instances where there are no maternal references. The ability to use any male
relative along the service member’s paternal line, increases the likelihood of
finding a suitable family reference to have on file.
“Without those family references, that sequence I get
from the bone is just a sequence if I don’t have anything to compare it to,”
said McMahon. “They are our greatest resources in identifying missing service
exclusions are just as important because they can rule-out individuals who may
have similar mtDNA but unique Y-STRs.
“It’s great when we make a connection to a single service
member,” said McMahon. “It gives us the best chance to find out who the service
member truly is.”