Forensic Lecture 7 PDF - Disputed Paternity

LECTURE (7) Disputed paternity   Paternity = Parenthood.  Paternity testing: the use of genetic testing methods to determine relationship () people, most commonly between alleged parents and children.  The alleged father can be proven to be the biological parent ① A baby claimed by...

LECTURE (7) Disputed paternity   Paternity = Parenthood.  Paternity testing: the use of genetic testing methods to determine relationship () people, most commonly between alleged parents and children.  The alleged father can be proven to be the biological parent ① A baby claimed by two sets of parents. ② Accidental interchange of infant in a maternity hospitals. ③ A father denies paternity of a child, Court-Ordered Testing ④ When lost child is recovered after a long time to determine whether he belongs to certain parents. ⑤ Legal complications in inheritance and child support ⑥ Immigration , Mass Disaster Victim Identification : used to confirm biological relationships  Before the advent of modern genetic testing, disputed paternity was often resolved through less reliable methods like witness testimony, cultural norms, and early scientific methods as blood typing which could only provide partial accuracy and inconclusive results.  ① Blood groups as (ABO system , Rh factor) ② Enzyme groups. ③ Protein groups. ④ HLA (Human Leukocytes Antigen). DNA Fingerprint.  Conducted during pregnancy. ① Non-Invasive Prenatal Paternity Testing (NIPT):  Uses the mother’s blood to analyze fetal DNA fragments  With no risk to fetus. Prenatal Testing ② Invasive Prenatal Testing:  Like amniocentesis and chorionic villus sampling (CVS)  Used to collect fetal DNA.  These methods carry a risk to the fetus. Postnatal Performed after the child’s birth. Testing ①  According to Mendel's law of inheritance there are 3 inheritable factors ①A ②B ③O  A and B are dominant and O is recessive.  The legitimate child ONLY can inherit the parents’ properties Every infant will inherit 2 factors, one from father and one from mother 2 dominant factors & not similar (A plus B) AB group The rarest group. 2 recessive factors (O plus O) OO - O gp The commonest group. 1 dominant (A or B) & 1 recessive (O) AO/BO - A or B gp 2 dominant & similar (AA or BB) A or B gp ②  Inherited by two genes D (dominant) and d (recessive).  When a homozygous Rh -ve woman (dd) married a homozygous Rh +ve man (DD)  The blood group of the child will be Rh +ve.  When a heterozygous Rh +ve woman (Dd) married a heterozygous Rh +ve man (Dd)  The blood group of their child may be Rh +ve or Rh -ve.  Easy ,rapid and Cheap and technique.  100% exclusion results.  Inaccurate as it could only exclude a man as the father, but it couldn't conclusively prove paternity.  Multiple Matches: Many individuals can share the same blood type. ① Personal identification. ② Disputed paternity. ③ Blood transfusion. ④ Organ transplantation. ⑤ Pregnancy.  Polymorphic enzymes mostly present in the red blood cells e.g. lactate dehydrogenase (tested by electrophoresis).  Rapid technique.  Non expensive.  Non-conclusive alone.  This method analyzed various proteins and enzymes found in blood (such as serum proteins) that are inherited in Mendelian fashion, meaning they are passed from parents to children, such as haptoglobins, and immunoglobulins.  Moderate Exclusion Power:  Could not definitively prove paternity ,Low Accuracy  HLA typing analyzes antigens found on the surface of white blood cells. These antigens are inherited from both parents  Alone it gives 98% probability of paternity.  Difficult technique  Expensive. ① Organ transplantation: i.e. tissue typing for both donor and recipient. ② Diseases association (e.g Ankylosing spondylitis). ③ Disputed paternity. ① PCR (Polymerase Chain Reaction):  Amplifies small samples of DNA to create a larger, testable sample. ② STR (Short Tandem Repeat) Analysis:  Compares short sections of DNA sequences at specific loci.  STR testing is the most commonly used method for modern paternity testing due to its high accuracy. ③ Y-Chromosome Testing:  Useful for testing relationships between males since Y-chromosome is passed from father to son. ④ Mitochondrial DNA (mtDNA) Testing:  Though primarily used for maternal lineage, mtDNA can sometimes play a role in complex paternity cases.  Alone it gives 100% probability of paternity  The only test which can by itself solve the problem of disputed paternity.  Difficult technique  Expensive. ① Sample collection. ③ Analysis (STR). ② DNA extraction and amplification. ④ Report generation  Buccal (Cheek) Swabs:  The most common and non-invasive method for collecting DNA.  Blood Samples:  Used when more substantial DNA quantities are needed.  Hair Follicles and Other Tissues:  Sometimes used if cheek or blood samples are unavailable.  Results are usually expressed as a probability, with a 99.9% probability of paternity typically indicating inclusion (the man is the father), and a 0% probability indicating exclusion. The DNA profile of the alleged father matches The DNA profile does not match, excluding the the child, confirming biological parentage. alleged father as the biological parent.  ① Informed consent is required. ② The right to privacy must be respected for all parties involved ③ Legal requirements for maintaining confidentiality of test results. ④ the rights of the child remain central to the use of paternity testing in society  Before the advent of DNA testing, several methods were used to determine paternity.  While these methods lacked the precision and accuracy of DNA-based techniques, they were widely used in legal and medical contexts to assess biological relationships.  Below are the Pre-DNA Testing Methods (Blood groups as (ABO system , Rh factor) ,Enzyme groups ,Protein groups ,HLA (Human Leukocytes Antigen).  Paternity testing has revolutionized family law and forensic medicine, offering a reliable and scientific way to determine biological parentage.  Modern DNA testing methods provide high levels of accuracy and are essential tools in legal disputes, personal identification, and family relationship resolutions.  Ethical considerations around consent, privacy, confidentiality of test results and the rights of the child remain central to the use of paternity testing in society.