Can DNA be useful to federally-recognized tribes?

A few federally-recognized tribes, such as the Mashantucket Pequot of Connecticut, have
considered using Native American DNA tests for enrollment purposes. For the Pequot, as for
other wealthy casino tribes, the financial stakes of enrollment are high: the Pequot disburse
monthly payments to each member totaling thousands of dollars. If DNA could exclude those
who cannot legitimately claim Pequot ancestry, the financial benefits for the remaining tribal
members would be great.
However, these Native American DNA tests rarely (if ever) identify genetic markers for
particular tribes. Because no tribe has been completely isolated from other human groups
throughout history, very few genetic markers are present only in the members of one tribe. In
all likelihood, genetic markers found in the Pequot also exist in many other tribes.
Consequently, adoption of a DNA-based enrollment policy might actually expand the number
of individuals qualifying for tribal enrollment because individuals without Pequot ancestry
could claim membership based on the shared genetic markers.
This example should serve as a red flag to tribes: enrollment policies based on DNA alone could
backfire. Furthermore, because individual identity is shaped by more than genetic ancestry,
other enrollment criteria might be better able to meet the needs of land-based tribal nations.
Reservation residence or tribal community involvement, for example, can help ensure that tribal
members are also culturally connected to the tribe and committed to its future.
Some companies may encourage the notion that genetic ancestry alone makes an Indian,
though, because there is a potentially lucrative market in such over-simplification. For
example, the DNA testing company DNAToday has teamed up with DCI America (a for-profit
tribal management consulting firm) to sell “genetic identification systems” to tribes. Their $320-
per-person photo ID cards sport computer chips and list specific DNA markers. DNAToday
advocates tribal-wide DNA testing, and claims that their product is “100% reliable in terms of
creating accurate answers” to questions of tribal enrollment.

Extracting DNA from Your Cells

Cells from the lining of your mouth come loose easily, so you will be able to collect cells containing
your DNA by swishing a liquid around in your mouth.
The cells from the lining of your mouth also come off whenever you chew food. How do you think
your body replaces the cells that come off the lining of your mouth when you eat?
To extract DNA from your cells, you will need to separate the DNA from the other types of biological
molecules in your cells. What are the other main types of large biological molecules in cells?
You will be using the same basic steps that biologists use when they extract DNA

Getting Your Sample of Cells

Obtain a cup with sports drink. You will need to get thousands of your cheek cells in the sports drink
in order to extract enough DNA to see. Therefore you should swish the sports drink around in your
mouth vigorously for at least one minute. Then spit the drink back into the cup.

Step 1: Detergent

Add a small amount of detergent to a test tube (about 0.25 mL). Put a glove on the hand you will use
to hold your test tube, not the hand you will use to pour. Now carefully pour the drink containing your
cheek cells into the test tube with detergent until the tube is half full Dishwashing detergent, like all soaps, breaks up lipids. This is why you use detergents to remove
fats (which are lipids) from dirty dishes. Adding the detergent to you cheek cell solution will break
open the cell membranes and nuclear membranes and release your DNA into the solution.

Step 2: Enzymes

Add a pinch of enzyme (meat tenderizer) to your test tube. With your gloved thumb (or palm)
covering the top of the test tube; gently invert the tube five times to mix. Let the mixture sit for at least
10 minutes. While you are waiting, you will learn about the structure of DNA. Remove your glove
and throw it in the garbage.


Why am I adding enzymes?

The nucleus of each of your cells contains multiple long strands of DNA with all the instructions to
make your entire body. If you stretched out the DNA found in one of your cells, it would be 2-3
meters long. To fit all of this DNA inside a tiny cell nucleus, the DNA is wrapped tightly around
proteins. The enzyme in meat tenderizer is a protease, which is an enzyme that cuts proteins into
small pieces. As this enzyme cuts up the proteins, the DNA will unwind and separate from the
proteins.
The protease in meat tenderizer actually comes from plants, but animals also make proteases.
Where in your body do you think you make protein-cutting enzymes?

Possible Results/Conclusions From DNA Test

When the results obtained from the standard sample from a known individual are all consistent
with or are all present in the results from the unknown crime scene sample, then the results are
considered an inclusion or nonexclusion. The term “match” is also commonly used when the test
results are consistent with the results from a known individual. That individual is included (cannot be excluded) as a possible source of the DNA found in the sample. Often, statistical frequencies regarding the rarity of the particular set of genetic information observed in the unknown
evidence sample and for a known individual are provided for various population groups.
It is possible for a falsely accused individual to be included as a source of a sample, particularly
if the test system used only tests at one or a few loci (e.g., the DQα). In this situation, additional
testing at more loci should be performed with the remaining evidence and/or DNA.
for that particular case from a legal perspective. Situations where this might apply are when the
results obtained are all consistent with the individual from whom the samples were collected


Exclusions

When the results obtained from the standard sample from a known individual are not all present in the results from the unknown crime scene sample, the results are considered an exclusion, a
nonmatch, or noninclusion. With limited exceptions, an exclusion of an individual at any one
genetic region eliminates that individual as a source of the DNA found in the sample.
In some cases where an exclusion is reported, it may be necessary to do additional testing for
that exclusion to be meaningful to the case or to provide evidence for exoneration. A situation
where this might apply is when the defendant is excluded as a donor of the DNA in a sexual
assault case, but no samples are available from the victim and/or consensual partners.



Inconclusive Result

Results may be interpreted as inconclusive for several reasons. These include situations where
no results or only partial results are obtained from the sample due to the limited amount of suitable human DNA or where results are obtained from an unknown crime scene sample but there
are no samples from known individuals available for comparison. In the latter case, the results
would be suitable for comparison once an appropriate sample for comparison is tested.


Database

RFLP-based and PCR-based databases have been constructed and are continuing to be expanded
in many laboratories throughout the United States and the world with samples from convicted
sex offenders and convicted felons, as well as samples from unsolved crimes. These databases
will be especially helpful for linking previously unrelated cases and for screening a large number
of known individuals already convicted of a crime to newly tested crime scene samples.
DNA databases of mitochondrial sequences are being established that are currently being used
for statistical purposes. It is possible that databases containing mitochondrial sequences may be
constructed for comparison to crime scene samples in the future.

Testing in the Future

Testing of hair shafts using mitochondrial DNA sequencing likely will become more widely
available in the immediate future. It may be possible to isolate and test DNA from other samples
that are not routinely tested today (e.g., fingerprints).
Y-specific probes are sequences of DNA found only on the Y (or male) chromosome. Development and validation of these probes are in progress. These probes will be especially useful for
mixed samples in which the female component is not relevant or may make interpretation of the
results more difficult (e.g., sexual assault samples, fingernails from female victims when the
assailant is male) and in the analysis and determination of the number of male sources of DNA in
samples where there are multiple male contributors (e.g., multiple assailants and/or consensual
partners in sexual assault samples). Because Y chromosomes are inherited through the male lineage, Y-specific probe results may be used to link a crime scene sample to a particular family.
DNA probes useful for identification testing are being developed from many other organisms and
may be useful in crime scene investigation. There are reported cases in which DNA from cat hair18
and from a particular type of plant has been used to link individuals to a particular crime scene.
Progress is being made in developing technologies for miniaturization of DNA tests (e.g.,
microchip analysis) that may be applied to forensic testing in the future. Expansion of existing
technologies (e.g., sequencing of nuclear DNA) may emerge for forensic testing. Other as yet
unknown or undeveloped technologies may be forthcoming that could be applied to forensic
testing. It is likely that future tests could increase the sensitivity and speed of testing, as well
as increase the discrimination capability of a test to unique identification of an individual.

Chemical structure

Each nucleotide in RNA contains a ribose sugar, with carbons numbered 1 through 5. A base is attached to the 1 position, generally adenine (A), cytosine (C), guanine (G) or uracil (U). Adenine and guanine are purines, cytosine and uracil are pyrimidines. A phosphate group is attached to the 3 position of one ribose and the 5 position of the next. The phosphate groups have a negative charge each at physiological pH, making RNA a charged molecule (polyanion). The bases may form hydrogen bonds between cytosine and guanine, between adenine and uracil and between guanine and uracil. However other interactions are possible, such as a group of adenine bases binding to each other in a bulge, or the GNRA tetraloop that has a guanine–adenine base-pair.

An important structural feature of RNA that distinguishes it from DNA is the presence of a hydroxyl group at the 2 position of the ribose sugar. The presence of this functional group causes the helix to adopt the A-form geometry rather than the B-form most commonly observed in DNA.This results in a very deep and narrow major groove and a shallow and wide minor groove. A second consequence of the presence of the 2-hydroxyl group is that in conformationally flexible regions of an RNA molecule (that is, not involved in formation of a double helix), it can chemically attack the adjacent phosphodiester bond to cleave the backbone