Predictive, Forensic, and Carrier Genetic

Predictive, Forensic, And Carrier

Genetic Testing: Forensic, Predictive And Carrier

This work seeks to examine genetic testing in the light of the potential contribution of genetic testing specifically in the area of forensic testing, predictive testing, and carrier testing. Genetic testing is beneficial in today's society as both a technological and social adaptation improving information related to crime investigation and evidence and in the area of prediction of genetically inherited diseases for prevention and early detection of these diseases. According to the American Cancer Society, "recent scientific advances have allowed researcher to identify a growing number of genetic alterations that may indicate predisposition for developing cancer or other diseases. The ultimate goal of genetic testing research is the development of clinical applications for risk assessment, early detection and appropriate interventions for individual risk reduction and disease prevention." (2007)

I. GENETIC TESTING DEFINED

Genetic testing is also referred to as 'gene testing' and 'DNA tests' and is a process by which the individual's DNA is examined. DNA is the material which genes are composed of which serve to determine the specific characteristics of living things. DNA determines the individual's features and as well, genetic testing has the capacity to detect particular genes in terms of whether they are present, absent, or altered and specifically in detection of chromosome abnormalities through laboratory testing.

II. USE of GENETIC SCREENING

The work of Jacobs (1997) relates the potential sues of genetic screening and testing techniques in a work published in the Occupational Medical Journal. Jacobs relates."..appropriate biotechnology has produced the capability of linking identifiable genetic structures with particular effects. In turn, this raised the possibility of modifying genetic instructions to overcome health problems. DNA analysis also has applications in forensic science, enables us to study current health risks, and also to discover the health status of preceding generations from human remains, and to pursue the genetic origins of disease leading to prevention or cure." (1997; p.367) Additionally genetic testing has enabled the detection of mutation of genes due to exposure to radiation or chemicals." (Jacobs, 1997; paraphrased; p.368)

III. GUIDELINES for GENETIC TESTING

Guidelines for genetic testing proposed in 2003 by ten genetic-medicine-related societies focused toward incorporation of genetic testing into clinical practice resulted in the creation of guidelines concerning genetic testing for the purposes of: (1) clinical diagnosis; (2) carrier detection; (3) presymptomatic diagnosis; (4) disease susceptibility estimation; (5) pharmacogenetic diagnosis; (6) prenatal diagnosis and newborn screening for inborn errors of metabolism." (Guidelines for Genetic Testing, 2003) Carrier testing is conducted when "there is in a family a patient with autosomal recessive, X-linked recessive or unbalanced chromosomal translocation" for determining whether those being examined are carriers and if their offspring might be affected with the same disorder. (Guidelines for Genetic Testing, 2003; paraphrased) Genetic testing for prediction of disorders includes "presymptomatic testing that is almost completely predictable for the development of a single-gene disorder, and susceptibility testing that estimates the predisposition to a multifactorial disease or its risk." (Guidelines for Genetic Testing, 2003)

IV. MITOCHONDRIAL DNA SEQUENCING

The work of Jakupciak and O'Connell (2005) entitled: "NIST Physical Standards for DNA-Based Medical Testing" states that a "rapid, high-throughput sequencing protocol to detect mutations in the mitochondrial genome" has been developed by a research team from the National Cancer Institute NIST and Tetracore. Affymetrix is stated to have developed "a microarray chip that has improved the data collection and interpretation of mitochondrial genomic data." (Jakupciak and O'Connell, 2005) This chip has been sued to analyze the mitochondrial DNA isolated from various tumors and bodily flues. Mutations in the cancer cells are identified according to the nucleotide change and according to gene locations." (Jakupciak and O'Connell, 2005) This test was conducted in less than 10 minutes. Advances in Mitochondrial DNA Sequencing include: (1) Optimized high-throughput re-sequencing array; (2) early cancer associated mutations detected in 88% of patients; (3) non-invasive samples; and (4) easily interpretable array results and assay is easily transferred to clinical use. (Jakupciak and O'Connell, 2005; paraphrased)

V. FORENSICS GENETIC TESTING

Forensic identification through genetic testing involves scanning of 13 regions of the DNA, which is used to compile the data profile of an individual often referred to as a 'DNA fingerprint'. (Human Genome Project, DNA Forensics, 2006) Examples of genetic testing use of DNA in forensic identification are: (1) identification of potential suspects from DNA left at crime scene; (2) exoneration of those wrongly accused of crimes; (3) identification of crime and catastrophe victims; (4) establishment of paternity and other family relationship; (5) identification of endangered and protected species in aiding wildlife officials and in prosecution of poachers; (6) detection of bacteria and other organisms that may be pollutants of air, water, soil and food; (7) matching of organ donors with recipients in transplant programs; (8) determination of pedigree for seed or livestock breeds; and (9) authentication of consumables such as caviar and wine. (U.S. Department of Justice, 2003; DNA Forensics, 2006) DNA typing is accomplished through obtaining DNA samples through designing "small pieces of DNA probes that will each seek out and bind to a complementary DNA sequence in the sample. A series of probes bound to a DNA sample creates a distinctive pattern for an individual. Only one-tenth of a single percent of DNA differs from one person to the next. Scientists can use these variable regions to generate a DNA profile of an individual" (DNA Forensics, 2006) by using blood, bone, hair, and other body tissue samples. DNA technologies used in forensic investigations are inclusive of the following: (1) Restriction Fragment Length Polymorphism (RFLP); (2) Polymerase Chain Reaction (PCR) Analysis; (3) Short-Tandem Repeat (STR) Technology; (4) Mitochondrial DNA Analysis and (5) Y-Chromosome Analysis. (DNA Forensics 2006) RLFP is a technique used in analysis of the "variable lengths of DNA fragments" resulting from the digestion of a DNA sample with a unique type of enzyme which cuts DNA "at a specific sequence pattern known as a restriction endonuclease recognition site." (DNA Forensics, 2006) the presence or absence of specific recognition sites in a DNA sample generates variable lengths of DNA fragments, which are separated and hybridized with DNA probes that bind to a complementary DNA sequence in the sample. (DNA Forensics, 2006; paraphrased) the PCR analysis is used in making millions of exact DNA copies from a biological sample, which serves toward better analysis. The STR analysis is used for evaluation of specific regions within nuclear DNA. Mitochondrial DNA analysis is extremely valuable in 'cold cases' (National Institute of Justice, 2002) or those that have remained unsolved for a length of time. Finally, Y-Chromosome analysis relates to a chromosome passed "directly from father to son" making this type of analysis useful in tracing relationships among males.