DNA Terms, Definitions and History

History of DNA Testing DNA testing has a history rich in scientific discovery and application.

Genetic research, (the study of heredity in living organismsespecially in the discovery and understanding of DNA), has been an important component of the development and success of DNA testing. Thanks to the extensive research of DNA and genetics, many techniques with significant health and legal implications have been established, improving the quality of life for many people.

Understanding and using DNA applications have led to the scientific ability to accurately identify individuals, locate inherited diseases earlier, and successfully reduce the stress and ambiguity associated with determining biological relationships.

To learn more about the history of DNA and DNA technology, please refer to

Developing DNA Testing

Techniques for DNA testing have changed dramatically over the past century. They have been fine-tuned over the years in an effort to increase accuracy and improve the power of exclusion for DNA testing. Power of exclusion is the power of a test to eliminate a certain percentage of the population from being biologically related to an individual; for example, if a paternity test using blood typing has a power of exclusion of 30%, only 30% of the male population could be eliminated from being the biological father of a tested child.

In the early 1900s, the first attempts of genetic testing were made with the advent of blood typing. Quickly thereafter, techniques with higher powers of exclusion were adopted through serological and HLA tests. It was only in the 1980s that scientists began using DNA characteristics as evidence of biological relationships.

The evolution of techniques has led to an increase in the power of exclusion to more than 99% in many cases.

To learn more about the development of present-day DNA testing please read below.

Blood Typing In 1901, Austrian scientist Karl Landsteiner discovered blood types. He noticed that blood clumping often occurred when he mixed blood from two different sources together, and he determined that this clumping was a result of an immunological response.

Landsteiner's experiments, with contributions from Jan Jansky, ultimately revealed the four major blood types possible in humans. In 1930, he was awarded the Nobel Prize in Physiology or Medicine for this work. The four blood types &mdash A, B, AB, and O &mdash were differentiated based on the presence or absence of certain proteins called Antigen - a foreign substance or biological invader that elicits an immune response; the presence of antigens triggers the production of antibodies )in the red blood cell surface.

Identification of these blood types was a significant medical development, as it provided doctors the ability to more successfully perform blood transfusions with compatible blood. Blood antigens that are different from those normally found in a transfusion recipient's bloodstream are bound by antibodies and stimulate an immune response. Scientists quickly realized that patients with type AB blood were able to receive transfusions from all blood types and those with type O blood were able to donate blood to all blood types.

Upon his blood typing discovery, Landsteiner realized that blood types were inherited from one's parents. Scientists determined that a child's blood type was dependent upon the blood types of his or her parents. Below is a table of the blood type possibilities for a child based on his or her parents' types.

Almost 40 years after the discovery of the major blood types, Karl Landsteiner and Alexander S. Wiener discovered the Rh factors - inherited antigens often found on the blood cells; some individuals have these antigens (Rh+) while others do not (Rh-); the presence of Rh factors, in conjunction with blood typing, has been used in the past to determine paternity-- in 1937. The Rh system, named after the Rhesus monkeys being studied, is composed of two basic types: Rh positive (Rh+) and Rh negative (Rh-). These types are based on the presence or absence, respectively, of specific antigens.

Like the inheritance of blood types, the absence or presence of the Rh antigen in parents' blood determines the Rh blood type of the child. For instance, it is possible for an Rh- mother to give birth to an Rh+ child if the child's biological father is Rh+.

Along with the Rh system, other serological tests have been used for determining paternity, especially tests for the inheritance of Kell and Duffy antigens.

Ultimately though, these serological tests only produce a slight increase in accuracy when combined with blood typing for paternity testing. Their combined power of exclusion is only 40%; therefore they are not a reliable source for paternity identification.

HLA Typing In 1975, Peter Doherty and Rolf Zinkernagel identified human leukocyte antigens (HLA). HLA are proteins found everywhere in the body except red blood cells. They are especially prevalent in white blood cells. Many types of HLA exist, often varying greatly from person to person. Doherty and Zinkernagel were awarded the 1996 Nobel Prize in Physiology or Medicine for this discovery.

Since many types of HLA exist, scientists can use HLA typing for genetic identification. They are able to compare the types of HLA in different people and determine if the people are related based on similarities between these proteins. HLA have become increasingly important for identifying positive matches between donors and recipients of bone marrow transplants.

The degree of variation among HLA in different people provides for fairly accurate paternity testing, with a power of exclusion from 80 to 90% when combined with blood typing and serological testing. The accuracy of HLA typing increases with the rarity of a tested person's HLA. However, this procedure is normally performed serologically, requiring a relatively large amount of fresh (no more than a few days old) blood. Additionally, the collection process can be considered uncomfortable, especially for children, and cannot be performed on infants under the age of 6 months.

RFLP Technique In 1985, Sir Alec Jeffreys developed Restriction fragment length polymorphism (RFLP) - a process by which DNA samples are cut into specific fragments of varying lengths for analysis; a child's fragments will be the same length as the fragments of his or her biological parents; similarities in fragment lengths can be used to verify other biological relationships - which quickly became the standard technique for DNA testing throughout the 1980s. RFLP provided the world with the first form of genetic testing based on DNA, the body's genetic material.

Each person inherits a unique combination of DNA from both biological parents, and this DNA serves as the code for all of that person's biological characteristics. By comparing the unique genetic code of one person to that of an alleged relative (for example, comparing a child to an alleged father), one can see whether or not the two people are biologically related.

Using RFLP, scientists cut specific portions of DNA into fragments for comparison. These fragments have different lengths, depending on the location of certain markers for cutting the DNA.

In a family relationship test, one person's DNA fragments are compared with those of an alleged relative. If the fragments match each other, they are considered to be from biologically related people.

In the case of a paternity test, a child's DNA fragments would be compared to the fragments of the mother and alleged father. Since the child received half of his or her DNA from the mother and the other half from the father, his or her DNA fragments should match those of both parents. Half should match the mother's, and half should match the father's.

If the alleged father is not the child's biological father, the child's DNA will not match the father's. In some RFLP cases, it will appear that the child's DNA does not match either parent's; this situation requires extra analysis. Occasionally, mutations in the DNA occur, causing a mismatch of fragments. When this happens, statistical analysis is needed to determine the likelihood of a mutation and the biological relationship between the family members.

Despite the periodic complication of genetic mutations in this procedure, RFLP is highly accurate, with a power of exclusion of 99.99% and higher.

RFLP is a highly accurate test. However, because it requires a large amount of blood and a long processing time, it is not used as frequently today as it once was.

Restriction Fragment Length Polymorphism (RFLP)in DNA Testing - What is RFLP? Restriction fragment length polymorphism, or RFLP, is a technique for preparing a DNA sample for analysis through electrophoresis.

How does it work? The DNA sample is exposed to restriction enzymes that recognize and cut DNA at specific sequences surrounding variable number of tandem repeats, or VNTRs. VNTRs are short sequences of DNA that repeat a specific number of times, based on inheritance. When the restriction enzymes cut the DNA sample, the products are DNA fragments of different lengths. The fragments are further analyzed through electrophoresis. (See it's history below)

In DNA paternity testing using RFLP, a child's DNA is cut into fragments that match the biological parents' DNA fragment lengths. Half of the child's DNA fragments will be the same length as the mother's DNA fragments, while the remaining fragments will be the same length as the father's DNA fragments.

Sometimes a child will have fragments that do not match either biological parent. When this happens, the lab will perform additional statistical analysis to determine if an unmatched fragment was caused by a mutation or if the tested father is not the child's biological father.

Why use RFLP? RFLP has a high power of exclusion , typically equal to or higher than 99.99%. Through RFLP, labs are able to analyze samples with a high power of discrimination at fewer Locus/loci -( position or location of a gene on a chromosome) (usually 6 loci) than other tests require. This means that they only have to use a few loci instead of using as many as 14 to obtain conclusive results.

Despite its power, the RFLP technique is not as common as PCR. It requires large samples of blood from tested parties and can take up to 8 weeks for analysis. Since the advent of PCR technology, many laboratories have favored the use of small buccal samples and the fast turnaround time made possible by PCR. Additionally, PCR offers a similar and often greater power of exclusion.

History of Electrophoresis:
Electrophoresis After it has been fragmented and copied through RFLP or Polymerase chain reaction (PCR) - a technique for copying small Fragments - (pieces of DNA; often used for DNA testing and analysis) many times; it is one of the most common processes used in DNA testing) the DNA sample undergoes electrophoresis. Electrophoresis is a process by which the fragments of the DNA sample are separated and identified.

There are two forms of electrophoresis typically used in DNA testing: gel electrophoresis and capillary electrophoresis.

Gel Electrophoresis Gel electrophoresis is a common DNA separation technique. It is designed to separate fragments of a molecule based on the fragments' sizes and charges. Labs are able to identify the fragments based on their location in the gel.

Gel electrophoresis is performed after the DNA sample has been amplified. The sample is placed into a gel slab, typically made of agarose or polyacrylamide. After the sample is placed in the gel, it experiences an electric current, which is promoted by a negative pole, or cathode, at the top of the gel and a positive pole, or anode, at the bottom.

The DNA fragments in the sample separate across the gel. The smaller fragments travel farther towards the bottom of the gel. The larger fragments remain closer to the top. Based on the distance that they travel, the lab is able to determine the size and, subsequently, the identity of the fragments.

Capillary Electrophoresis Capillary electrophoresis works on the same principles as gel electrophoresis.

After the sample has been amplified, it is injected into a long, thin capillary containing a gel. The gel acts as a meshwork for the sample to travel through. An electric field runs through the capillary as well. The sample starts at the negative pole, or cathode, and moves towards the positive pole, or anode.

The sample fragments separate as they travel through the capillary.

The DNA fragments in the sample move through the capillary at different speeds. The speed of each fragment is determined by its size. The smaller fragments travel through the capillary faster than the larger fragments.

PCR Technique In 1983, Kary Mullis and members of the human genetics team at Cetus Corporation developed a genetic replication technique called polymerase chain reaction (PCR). After several years of fine-tuning the process, PCR became the most popular DNA replication technique by the 1990s. Kary Mullis was awarded the Nobel Prize in Chemistry for this work in 1993.

The popularity of PCR is based on both the sample size and the processing time it requires. DNA testing utilizing PCR can be performed in a matter of hours with a very small DNA sample.

In PCR, scientists isolate a small amount of DNA (an amount easily obtained from a Buccal swabbing - (a DNA collection process by which a bristle or cotton-like material, often similar to a large Q-tip, is used to rub the inside of the cheek; this process is painless and quick )

They then copy regions (or loci) on the DNA many times to establish large quantities of DNA fragments from the copied regions. PCR can be used to copy any region of DNA.

For PCR use in paternity testing, scientists isolate a small amount of DNA and copy many specific DNA fragments (or loci) that help identify and differentiate people. Fragments from one individual are compared to fragments from other individuals, as done in RFLP, and relationships are determined based on the similarities and differences between the DNA fragments or genetic profiles.

Polymerase Chain Reaction (PCR) - Amplification of DNA Samples What is PCR? Polymerase chain reaction, or PCR, is a process by which small samples of DNA are made larger, or amplified. By using PCR, labs are able to create larger batches of DNA from small samples for easier analysis.

How does it work? A sample of DNA is collected and exposed to the "PCR mix," a solution of primers, free nucleotide bases, and DNA polymerase in a buffer. Each of these components plays an important part in ensuring that the DNA is amplified.

There are three basic steps in PCR:
1. Denaturing: Separating the DNA Strands The first step of PCR is denaturing the DNA sample. The DNA is heated to approximately 95 degrees Celsius, causing the DNA to unwind from its normal shape and the two backbone strands to separate. At the end of this step, the lab has two single strands of the DNA backbone for each molecule of the original DNA.
2. Annealing: Attaching the PCR Primers After the DNA is denatured, the sample is cooled to approximately 60 degrees Celsius and molecules called primers bind to the two single DNA strands. The primers prepare the strands to reform into complete DNA molecules.
3. Elongation: Rebuilding the DNA Strands Once the primers have attached to the single DNA strands, the sample is heated to approximately 72 degrees Celsius and the DNA polymerase is activated. The polymerase recruits free DNA bases in the sample solution, matches them to the single DNA strand, and extends the primer. This process, called elongation, results in a double-stranded copy of the original DNA sample. At the end of these three steps, the lab has two copies of the original DNA sample. This three-step process is repeated at least 30 more times, ultimately resulting in millions of copies of the original DNA sample.

Why use PCR? Most DNA testing laboratories now use PCR, because it allows them to make many copies of the samples, reducing the amount of time necessary for analysis. With other methods, such as RFLP, larger samples are needed. With PCR, labs can copy a small sample many times to create a larger batch of sample copies for easier analysis. Essentially, the more copies of the sample they have, the faster they can complete the DNA test

DNA Technology Introduction DNA technology is a powerful tool for verifying biological relationships and identifying individuals.

If you choose to order or participate in a DNA test, certain DNA technologies will be employed to test your samples. Thanks to major advancements in DNA isolation and separation techniques over the past 10 years, DNA tests can be completed in just a short time.

When the laboratory receives your DNA sample, the process begins. Although there are several different techniques that labs can use for testing DNA, the overall process is typically the same.

Testing Process Overview For a standard DNA test, the lab will:
1. Extract the DNA samples.
2. Denature, amplify, and label small DNA samples into smaller DNA segments with fluorescent tags called STR through PCR.

OR

Denature and label large DNA samples into smaller DNA fragments with fluorescent tags through RFLP or mtDNA.
3. Separate and identify the DNA segments through gel electrophoresis or capillary electrophoresis.
4. Analyze and interpret the DNA segments to determine relationships or identity.
5. Verify and release the results to the interested parties.

At each step, most labs will statistically analyze the raw data for the samples before moving on to the next step.

DNA Technology The most common technologies used in DNA testing include:
Short Tandem Repeat (STR) Polymorphism
What are STR polymorphisms? Short tandem repeats, or STRs, are short (typically between 2 and 10 base pairs long), variable regions of DNA that repeat many times. Over generations, these regions of DNA have developed polymorphisms, variations in the number of repeats in the DNA sequence. This has made them useful as unique genetic identification markers. The number of repeats varies from individual to individual, and the repeats are inherited in a predictable pattern from parent to child.

Why use STRs?

Since STRs are inherited from both biological parents, they can serve as useful DNA fragments for identification.

Labs examine STRs at specific loci and identify the number of repetitions found in a particular individual's DNA. Because children receive half of their DNA from their mother and half from their father, it is possible to verify the biological relationship between parents and children by comparing their STRs. STRs are used in many other DNA tests as well.

Labs typically use STRs more often than other loci because they are small, making them easily amplified through PCR

See above for Restrictive Fragment Length Polymorphism (RFLP)

See above for Polymerase Chain Reaction (PCR)

See above for Electrophoresis

Mitochondrial DNA (mtDNA) Sequencing
What is mitochondrial DNA sequencing? Mitochondrial DNA sequencing, or mtDNA sequencing, is a process by which scientists analyze and compare samples of the DNA located in the mitochondria of the body's cells. This technique is valuable because mitochondria can serve as a useful source of genetic material when nuclear DNA samples are unavailable or degraded.

To learn more about how mtDNA sequencing is used for genetic and DNA testing, see below.

How does it work? About mtDNA Mitochondrial DNA is a small, circular DNA molecule found in mitochondria, which are small organelles found within all cells of the body. Unlike nuclear DNA, which only exists inside the nucleus of a cell, mtDNA is found in multiple copies outside the nucleus.

This high concentration of mtDNA in cells makes it especially useful for testing samples that have low nuclear DNA concentration or are old and/or degraded. For this reason, mtDNA is often used in forensic testing and other situations that require genetic identification.

Mitochondrial DNA is almost exclusively inherited from the mother; less than 0.01% of a person's mtDNA is influenced by the father. Essentially, a mother will pass an exact copy of her mtDNA on to her child. This inheritance pattern allows scientists to trace maternal lineages back through several generations.

mtDNA is composed of two regions arranged in a ring shape. These regions are the control (or non-coding) region and the coding region. The control region is of most interest to scientists as it contains two variable segments, Hypervariable Region I (HVI) and Hypervariable Region II (HVII). In humans, these regions have a higher mutation rate, such that even though a mother passes on the exact copy of mtDNA to her child, enough variation has occurred through several generations that scientists can differentiate among different maternal lineages.

About mtDNA Sequencing An mtDNA test uses sequencing, the process of determining the nucleotide sequences of a person's DNA. In a relationship test, the mtDNA sequences of samples from two or more individuals are compared.

mtDNA sequencing is performed in 5 basic steps:

1. Sample preparation When a sample for mtDNA testing is received, it first undergoes a preparation process. Any potential contaminants on the sample are removed. Then the sample is placed in a solution that lyses the mitochondria, causing the mtDNA to be released.

2. mtDNA Extraction After the mitochondria are lysed, the mtDNA remains mixed in the sample solution. Additionally, unwanted biological molecules, such as proteins, may still be attached to the mtDNA. To be separated from the excess molecules, the mtDNA is exposed to an organic chemical.

Once the mtDNA is cleaned of these molecules, the solution is separated and filtered, leaving the mtDNA completely free of the mitochondria and excess biological molecules.

3. PCR Amplification Using PCR technology, the hypervariable regions of the mtDNA are copied and amplified. At the end of this step, there are more than one billion copies of the mtDNA sample's hypervariable regions.

4. mtDNA Purification and Quantification The amplified DNA must be purified before it can be sequenced. A chemical is added to the mtDNA sample to remove any excess PCR reagents remaining in the solution.

The sample is then quantified to determine the concentration of the amplified mtDNA regions. If the concentration is low, the sample will undergo PCR again to increase the amount of amplified DNA. The sample will continue to undergo PCR and purification until a high concentration of DNA is achieved and the sample is ready for sequencing.

5. Sequencing Sequencing of the mtDNA's hypervariable regions is a lot like the PCR technique. The sample is denatured, annealed, and elongated in the same way as PCR, but additional molecules are present in the reactions. These molecules, called dideoxyribonucleotides, act like the free nucleotides in a standard PCR solution; however, instead of promoting DNA strand growth, they stop it.

Specifically, an mtDNA double strand is denatured into two single strands. These strands are exposed to the PCR reagents (primers, nucleotide bases, DNA polymerase, and buffer) and dideoxyribonucleotides (commonly called dideoxy bases). The dideoxy bases behave in the same way as the other nucleotides in the PCR solution, but they contain a fluorescent tag and arrest DNA polymerization when incorporated into a growing DNA strand.

The strands start binding with nucleotides during elongation. Randomly (less than 5% of the time), the strand will bind with a dideoxy base instead of a normal nucleotide and the elongation of the strand will stop. This results in a fragment of double-stranded DNA.

Gel electrophoresis is performed to separate the different fragments based on their size. The smaller pieces of DNA will travel to the bottom of the gel.

The sequence of the mtDNA is determined based on the location of the fluoresced strand in the gel. The complete sequence of the mtDNA is often automated, as the sequence is typically large.

See the image below for identifying the sequence based on location of the tags in the gel.

Why use mitochondrial DNA sequencing? As mentioned earlier, mtDNA sequencing is useful for obtaining genetic material from samples that have low concentrations of nuclear DNA or are old or degraded.

More specifically, because mtDNA is highly preserved between generations, scientists use mtDNA testing for following genetic matrilineages to study the migration of humans over time. mtDNA testing is also used to provide additional information in genetic reconstruction cases and siblingship studies.

mtDNA Test Mitochondrial DNA testing is a technique used to determine if people are biologically related through the maternal genetic line. Mitochondrial DNA, or mtDNA, is the DNA found in the Mitochondrion/mitochondria (- an organelle in the cell that is responsible for respiration and energy; it contains unique DNA that can be used for mtDNA testing) of the body’s cells. This genetic material is passed down almost completely unchanged from mother to child, making it quite useful for identifying biological relatives.

Testing of mtDNA is different from other DNA tests because it requires sequencing. Sequencing determines the organization of the DNA bases, which is unique to each family.

To learn more about this technique, visit the Mitochondrial DNA Sequencing section of the page.

When is mtDNA testing used? Mitochondrial DNA testing is often used in maternity cases when the mother is missing or unavailable. The mtDNA test is also used in adoption cases to reunite biological relatives with people who have been adopted and in immigration cases to determine biological relationships between family members. This test may also be used to supplement historical information in genealogical research.

Who is typically involved? A child and maternally related family members are typically involved in an mtDNA test.However, the people involved will depend on the goal of the test.

How are the samples collected? Samples for mtDNA tests can be collected in several ways, but the most common collection method is the buccal swab.

To learn more about buccal swabbing and other collection techniques, visit the Sample Collection page.

How long can the results take? Since mtDNA testing requires sequencing, the turnaround time for the results is typically longer than other DNA tests. Most DNA testing companies that offer mtDNA tests can release results in 2 to 4 weeks after the samples are received at their labs.

How conclusive are the results? An mtDNA test can accurately determine whether two or more individuals are maternally related. Differences in base pair sequence between the tested individuals' mtDNA samples are recorded, and the sample's DNA sequence is reported by detailing these differences. A Relatedness or Maternity Index can then be calculated for the mtDNA sequence by using the frequency with which the particular sequence has been observed in a particular population (i.e., race).

What is the typical price range for mtDNA testing? DNA testing using mtDNA typically costs between $300 and $500.

What else should you know about mtDNA testing? You should consider the potential use of your mtDNA test results before you decide between in-home and chain of custody collection. If you are looking for peace of mind or simply for curiosity’s sake, in-home testing is acceptable for your needs. However, if you think that there is the potential your test results could be used in a legal case, you should consider having a chain of custody test instead.

Adoption Finding a family to parent your child or being a child who is adopted can be challenging. Much ambiguity surrounds adoption, and oftentimes, birthparents and children who were adopted seek information about each other.

DNA testing can provide irrefutable and reliable genetic information about birth relatives, giving hope and easing the minds of many people touched by adoption.

To learn more about the use of DNA testing in adoption cases, click on any of the links below:

Uses of DNA Testing in Adoption Cases DNA testing can be used in many situations surrounding adoption, as it provides indisputable answers and potentially life-changing evidence for those seeking information.

For adoption cases, DNA testing may be used to:

Identification and Reunion Reuniting with one's biological family is one event in adoption cases that often requires DNA testing. Particularly with cases from before the 1980s, information on the biological families of adopted children was hard to access and many people relied on what little facts they knew about the adoption cases to locate biological family members. DNA testing makes it possible for adopted children and their biological families to definitively confirm their biological relationships.

Adoption Registries With the use of DNA testing on the rise in adoption cases, several registries have been established to reunite adopted children with their biological families. These registries aim to collect DNA profiles and place them in a database to await matches between biological relatives.

Medical History In addition to discovering their biological families, adopted children can also learn about their families' medical history. If adopted children know who their biological families are, they can determine the genetic health risks they may have. If they do not know who their biological families are or the health risks their families may have passed on to them, adopted children can undergo genetic screening. Genetic screening allows scientists to review adopted children's DNA to locate potential illnesses or health concerns that they may have inherited from their biological families.

International Adoption Requirements Another use of DNA testing is in international adoption cases. In response to The Hague Convention on Intercountry Adoption, many countries require that birthparents undergo DNA testing with their child to be adopted. By proving that the parents are biologically related to the child before choosing an adoption plan, the adoption agency and/or government agency can be sure that the parents willingly placed the child into adoption and did not lose the child because of coercion or the adoption black market.

Peace of Mind Finally, DNA testing is often used in adoption cases to provide peace of mind to individuals. Sometimes biological family members and adopted children do not want to be reunited, but they would prefer having the peace of mind of knowing their origins. Sometimes this peace of mind is accompanied by a desire to learn about the family medical history.

Common DNA Tests Used in Adoption Cases Many DNA tests are useful in adoption cases. Interested parties in adoption cases should choose the DNA test that is most appropriate for their situation.

Some of the most common DNA tests used for adoption cases are listed below:

Guidelines for Adoption Cases Because of the sensitive nature of adoption cases, extra measures are taken to protect the privacy of the parties involved. DNA testing in adoption cases requires exceptional discretion and consideration for state laws by both the DNA testing company and the parties being tested.

To ensure that both discretion and legal consideration are maintained,

Chain of custody DNA test - (a legal term for a test that is performed to ensure the integrity of the results; typically, the results of a chain of custody test are court admissible; these tests cost more than in-home tests because of the collection and administrative procedures necessary to ensure the chain of custody is strictly followed)

DNA testing services should be used. Using chain of custody testing services will provide a person more freedom in accessing both Identifiable information (adoption) - descriptive details in an adoption case that may lead to the positive identification of an adopted person, birth parent, or other birth relative; mutual consent between the adopted person and the birth family is typically required to access this information; this information frequently includes the current name and contact information of a person involved in an adoption case )

and

Non-identifiable information (adoption) - descriptive details about adopted persons and their birth relatives that are generally released to adopted persons over the age of 18 in the United States; some states charge fees for the release of this information; this information often includes:

People interested in accessing information about specific adoption cases should learn more about the laws in both the state where the birth took place and the state where the adoption took place, if different.

To learn more about state laws on adoption and information access, click on the links to the Child Welfare Information Gateway and National Adoption Information Clearinghouse (NAIC) below.

To learn more about the use of DNA testing in international adoption cases, click on the link below. Inter-Country Adoptions go to www.uscis.gov