everyone is born with a unique genetic blueprint known as dna . as half of the dna of an individual is inherited from the biological mother and half from the biological father , the comparison of the dna sequences of a person to that of another person can show if one of them is derived from the other or not . specific sequences are usually looked at to see if they are copied verbatim from one of the individual 's genome to the other . saliva is a potentially useful source of genomic dna for genetic studies since it can be collected in a painless and non - invasive manner . consequently , dna testing has become the most accepted method to determine identity within the legal and scientific communities . the dna parentage testing is the most reliable and powerful method of proving or disproving parentage for legal , personal , or medical reasons . this test also resolves disputes , and helps streamline court proceedings to settle child support and custody cases . the standard methods for paternity testing are polymerase chain reaction ( pcr ) , short tandem repeat ( str ) , restriction fragment length polymorphism ( rflp ) , and dna sequencing . a female victim aged 24 years lodged a complaint in barabanki police station for being raped a year back by mr . x. victim claims to be mother of his 3 months old baby ( girl ) and wanted justice and compensation . the case was referred to the department of medical genetics , sanjay gandhi post graduate institute of medical sciences , lucknow for paternity testing . saliva samples were collected from the oral cavity of the baby , and blood samples were collected from the mother and suspected father . extraction of genomic dna in both blood and salivary samples was done using phenol - chloroform method published in our previous research article . it was followed by its qualitative and quantitative analysis using spectrophotometer and amplification of dna by using pcr . further panel of markers were selected for this purpose ; few of them were used because of their positive response shown in our previous study like apob3'hvr , hum - vwf-1 , hum - f13a . other strs markers used were hum - vwa , hum tho1 , hum - tpo , hum - fes , hum - hprt , and hum - fga . all the above markers were analyzed on poly - acylamide gel electrophoresis ( page ) . we analyzed few of the autosomal str markers on 310 fragment analyzer ; these were d3s1342 , d8s4321 , and d115432 . also , we analyzed human leukocyte antigen ( hla ) gene complex markers like class i- a , b , c and class ii- dr , dq on agarose gel . analysis of hum - vwf-1 marker [ figure 1 ] showed that bands in the suspected father ( sf ) did not match with the bands in the baby ( b ) , whereas bands in the baby matched with the bands in mother ( m ) . analysis of hum- fes marker showed that bands in the suspected father did not match with the bands in the baby , whereas one of the bands in the baby neither matched with the mother nor with the suspected father . analysis of hum - vwf-1 marker using page , l - dna ladder analysis of hla -a gene complex using agarose gel [ figure 2 ] showed that one out of 2 bands in the suspected father did not match with the bands of the baby . the analysis of hla -c gene complex using agarose gel [ figure 3 ] showed that one out of 2 bands in the suspected father did not match with the bands in the baby . analysis of hla -a gene complex using agarose gel analysis of hla -c gene complex using agarose gel based on the dna analysis , the pattern of bands revealed in the child 's dna was compared with that in the mother 's dna . all bands that matched in position and relative intensity are , or could be , maternal in origin . thus , all of the remaining bands in the dna fingerprint of the child must have been inherited from the biological father . in this present case , all of these remaining bands in the child were not present in the dna fingerprint of the alleged father . x ( suspected father ) as the biological father of the baby because they do not share sufficient genetic markers as there was no common allele between the putative father and baby at 5 loci . comparing the dna sequence of suspected father , mother and the baby [ figure 4 ] showed that one of the sequences in the baby was solely derived from the mother . as the tested alleged father does not match the child on 3 or more genetic sites , the alleged father is not the child 's biological father . forensic science ( legal medicine ) is a specialism that aims to help judges and juries solve legal issues , not only in criminal law but also in civil cases . dna fingerprinting is a technique used especially for identification ( as for forensic purposes ) by extracting and identifying the base - pair pattern of an individual 's dna . the process of dna fingerprinting was developed by alec jeffreys in 1984 , and it first became available for paternity testing in 1988 . the basic function of paternity testing is to exclude the maximum number of individuals that could be biological fathers of the child in question . this is done by identifying the obligate allele in the child and determining if the alleged father also carries this allele . for a paternity test to be considered to be of high quality , at least 16 loci must be analyzed during testing , which was done in the present case . if dna of the child and alleged father show exclusions at 3 or more loci , then the alleged father is considered to be excluded as the biological father of the child . in the present case , the probability of paternity would be 0.00% as 5 of the bands present in baby did not match the bands of suspected father . generally , fresh whole blood or blood - stained material is the primary source of an individual 's dna used as a standard for comparison to evidentiary material in dna typing . various studies along with our previous study have demonstrated that saliva and saliva - stained materials are good source of dna . moreover , the dna banding patterns obtained from saliva or saliva - stained material are indistinguishable from the patterns obtained from blood or hair from the same individual . in the present case , since the baby was 3-months - old , fairly large volumes of saliva was collected in a painless and non - invasive manner . most paternity testing is done for financial reasons , i.e. to establish legal responsibility and provide for child support . such testing is clearly an important tool in civil courts when the paternity of a child is in question . as saliva is a rich source of genomic dna , it can be used as an alternative source of dna for known standards ( blood ) . as it is well said , it 's important to give justice to the victim when the alleged father is proved to be the biological father , but it is also equally important to exclude the innocent .
everyone is born with a unique genetic blueprint i.e. its own genome . 
 special locations called loci on different chromosomes display predictable inheritance patterns that could be used to determine biological relationships . 
 these locations contain specific dna sequences , called markers , which forensic scientists use as identifying marks for individuals . 
 saliva is a potentially useful source of genomic dna for genetic studies . 
 paternity testing is based on the premise that we inherit half our dna from our father and half from our mother . 
 therefore , persons who are biologically related must share similar dna profile . 
 conversely , the absence of similarities in the dna profiles of the child and the alleged father is used as proof that no biological relationship exists . in this paper , 
 a female complained for being raped a year back by mr . 
 x and accused him of being father of her 3-months - old baby girl . 
 dna testing was done using saliva for the child and blood sample from the mother and the suspected father . 
 the finding presented here allows the use of saliva as an alternative source of blood .