Applications of DNA Analysis Using DNA to Identify People Biomedical Technology I

DNA Each person’s DNA is unique, it is like a fingerprint Body tissues such as blood, semen, saliva, skin or hair can be tested to see if the DNA matches a particular person Sequencing all 6 Billion base pairs would be very difficult DNA fingerprinting concentrates on a few regions of DNA known as a short tandem repeat or STR.

STR’s STR’s are short three to four nucleotide sequences of DNA that repeat over and over and are found in non-coding regions of DNA. The FBI (Federal Bureau of Investigation) maintains a database that contains DNA profiles of convicted criminals, missing persons, some arrestees and unidentified remains. The number of STR repeats at a particular location is known as an allele and varies from person to person

STR’s While it is common for two people to share the same alleles at one location, it would be unlikely for even closely related people to have the same alleles at all 13 locations! As of 2013, there have been 307 post- conviction exonerations in the U.S. based on DNA evidence. DNA is used to identify close relatives as well Numerous laboratories perform tests to establish paternity and other family relationships in custody, inheritance, immigration and other legal cases.

STR’s To establish paternity, labs usually compare results at 16 loci, including the 13 core loci used by the FBI.

Other types of Identification Another type of identification is through genetic testing Angelina Jolie discovered through genetic testing that she shared her mother’s risk for breast and ovarian cancer due to the inherited tumor suppressing BRCA gene In 2008, the U.S. enacted the Genetic Information Nondiscrimination Act, or GINA, to prevent employment and insurance discrimination based on genetic information.

Identifying Diseases Newborn screening programs test infants for genetic and other conditions that should be treated immediately but might not be obvious to the doctor or parents. Babies with phenylketonuria need a special diet from birth to avoid mental retardation, seizures and albinism Babies with sickle cell disease need specialized care to prevent infections and organ damage and to treat pain

Genetic Testing Provide a person with a variety of information on his or her ancestry, potential relatives and gene variations relative to a wide range of medical conditions with a known genetic component Helps adoptees understand their risks for various medical conditions and in some cases, find biological relatives 23 and Me provides ancestry and medical risk information by looking at more than 1 million places where the human genome is known to have single nucleotide variations or SNPs

Genetic Testing Important for understanding the prognosis and treatment of certain types of cancer Cancer researchers have been able to match specific treatments for specific mutations. Examples: Breast Cancer patients whose cells test positive for receptors known as HER2 are helped by the drug Herceptin which blocks these receptors A drug called XALKORI helps the 3%-5% of lung cancer patients whose cancers test positive for a mutation in the anaplastic lymphoma kinase gene

Techniques for Analyzing DNA Karyotyping is a technique to look at a set of chromosomes to check for abnormalities. Spectral karyotyping and fluorescence in situ hybridization, or FISH, use probes that stick to known places on the chromosomes in order to color, or “paint”, specific parts of the chromosomes, making it easier to spot certain types of rearrangements.

Polymerase Chain Reaction PCR is an extremely important technique in DNA testing. PCR is used to make enough copies of DNA segments so the DNA can be sequenced, profiled or tested for a particular genetic disorder. Millions of exact copies of a specific sequence can be made in just a few hours

Gel Electrophoresis Technique for separating molecules by length and charge, including DNA, RNA and proteins DNA fragments of interest contain the STR regions PCR is used to make millions of copies of these specific fragments of DNA from a sample The fragments are inserted into a gel and electricity is applied to attract the molecules through the gel. The smaller fragments with fewer STR repeats move faster

Gel Electrophoresis The fragments are stained, resulting in a banded pattern that is compared to a reference pattern to determine which STR alleles are in the sample

Microarrays Can detect the presence and activity of thousands of genes at the same time DNA probes are put on a glass slide, chip or membrane in an organized array They are designed to attach to complementary DNA When the sample DNA matches the probe DNA, it will stick together and made to glow This tells the researcher what DNA or RNA was found in the sample.

Microarrays This technology is used to give people detailed information about their ancestry and genes for particular traits. Microarrays are used to study which genes are active during development and in cancer cells, as well as cell response to pathogens and various treatments.