You Are Not The Father
Role of DNA in Paternity Testing
Egyptian society suffers from increasing in the number of divorce cases which leads to different problems. One of them is the children's street that is a result of paternity issues. Paternity cases are caused due to huge problems between married couples because women may be entering a sexual partner in her life so the child will be not the son of her husband. paternity testing is the best technique which is used in forensic in order to solve these issues.
You Are Not The Father
Examining the impact of paternity testing
- By the end of 2018, there were about 17,000 divorce cases in Egypt which marks a 13.4% rise in divorces.
- According to the Central Agency for Public Mobilisation and Statistics (CAPMAS), the total number of divorces reached 199,867 in comparison to 180,244 in 2014. In Egypt, most women marry between the age of 20 and 25 while most men marry between the ages of 25 to 30. Men between 60 and 65 years and women over 65 years had the lowest marriage rate so that they had the lowest judicial problems between them like the paternity issues.
- Paternity issues always happen due to huge problems between married couples. It happens when married women enter a sexual partner in her life so the child will be not the son of her husband. There are also many cases that lead to paternity and also lead the father to deny his son or daughter and vice versa.
- The science has developed and played important role paternity problems by solving these problems through different techniques. The old one is ABO blood typing and the latest one is STR. (Aswatmasriya.com, 2017).
- The aim of this research is to identify the biological parents and to prove that the case is inclusion or exclusion by extracting the DNA sample from a blood sample or from a buccal swab in order to identify the 16 codes core STR loci with chromosomal positions.
- Egypt faces many paternity cases that cause several issues for children who grow up and didn't know their biological parents. These cases have a bad effect on the children's psychology that may lead them to fail in their future and it is also one of the main reasons for children's streets. Some estimates say that two million children are living on Egypt's streets. A quarter of street children are to be less than 12 years old, two-thirds between the age of 13 and 16, and just under 10 per believed cent over 17. They find themselves on the street for a variety of reasons, including family breakdowns due to divorce and remarriage.
- Some of these Egyptian children are victims for backward society and they are deprived of their rights in education, health, and social care and especially the right to family care so that the sciences present the STR polymorphism in paternity analysis to solve the paternity cases and return the right of these children in family care.
Modern DNA typing procedures
Nowadays, the most common technique that is used in paternity cases depends on the identification of 16 STR core loci with the chromosomal position
- These loci are identified in each individual related to the paternity case. After identification, the DNA profile of the alleged father and mother is compared to the DNA profile of the child. The process steps of paternity testing include five steps. These five steps are illustrated in the sample collection, DNA Extraction, quantification, amplification, and STR analysis. In the sample collection step, the DNA is extracted from its biological source moreover it is measured in order to evaluate the quantity of DNA recovered in the quantitation step. In the amplification step, specific regions of the DNA are targeted and copied with polymerase chain reaction which is known as PCR. Finally, in the STR analysis step, the Commercial kits are commonly used to enable simultaneous PCR of 13 to 16 short tandem repeat (STR) markers. STR alleles are interpreted relative to PCR amplification artifacts following separation by size using capillary electrophoresis and data analysis software. (Sweet et al. 1997, Pang & Cheung 2007, Butler, 2011)
DNA quantitation using RT-PCR
To ensure that DNA recovered from extraction is human rather than from another source such as bacteria, human-specific DNA quantitation is required. Only after DNA in a sample has been isolated can its quantity and quality be reliably assessed. Detection of the appropriate amount of DNA template to include in PCR amplification of short tandem repeat loci avoiding off-scale data and associated artifacts are the main purpose of DNA quantitation in paternity casework. PCR amplification of too much DNA results in overblown electropherograms that make interpretation of results more challenging and time-consuming to review. Too little DNA can result in loss of alleles due to randomly amplification and failure to equally sample the STR alleles present in the sample. A number of DNA quantitation tests have been used over the years to estimate the amount of total DNA or human DNA present in a sample. Several DNA quantitation tests are used in many approaches such as yield gels, PicoGreen, end-point PCR, real-time quantitative PCR, UV absorbance, and slot blot. (Nicklas & Buel 2003 and Barbisin & Shewale, 2010).
- UV absorbance is the most common technique to determine DNA yield and purity. It could be argued that fluorescence measurement is easier. Absorbance measurement is simple, moreover, it requires commonly available laboratory equipment. All that is needed for the absorbance method is a spectrophotometer equipped with a UV lamp, UV-transparent cuvettes depending on the instrument, and a solution of purified DNA. Absorbance readings are performed at 260nm (A260) where DNA absorbs light most strongly, and the number generated allows one to estimate the concentration of the solution. To ensure the numbers are useful, the A260 reading should be within the instrument's linear range (generally 0.1–1.0).
- DNA concentration is estimated by measuring the absorbance at 260nm, adjusting the A260 measurement for turbidity (measured by absorbance at 320nm), multiplying by the dilution factor, and using the relationship that an A260 of 1.0 = 50µg/ml pure dsDNA.
Real-time PCR is known as quantitative PCR because it analyzes the cycle to cycle change in fluorescence signal resulting from the amplification of a target sequence during PCR. This analysis is performed without opening the PCR tube and therefore can be referred as a homogeneous detection assay. There are two common approaches that are used in DNA quantitative either the fluorogenic 5' nuclease assay-known as TaqMan or intercalating dye such as SYBER Green. Quantifying the DNA in a sample is used to detect the amount of DNA for adequate amplification. The smallest volume required for the reaction ranges fro, 0.5 to 1.0 ng.
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© 2020 Kareem Essam Mohamed