Forensic study of sex determination using PCR on teeth samples

Insulin-Like Peptide 3 (INSL3) Serum Concentration During Human Male Fetal Life

Context: Insulin-like peptide 3 (INSL3), a protein hormone produced by Leydig cells, may play a crucial role in testicular descent as male INSL3 knockout mice have bilateral cryptorchidism. Previous studies have measured human fetal INSL3 levels in amniotic fluid only. Objective: To measure INSL3 serum levels and mRNA in fetal umbilical cord blood and fetal testes, respectively. Design: INSL3 concentrations were assayed on 50 μl of serum from male human fetal umbilical cord blood by a non-commercial highly sensitive and specific radioimmunoassay. For secondary confirmation, quantitative real-time PCR was used to measure INSL3 relative mRNA expression in 7 age-matched human fetal testes. Setting: UT Southwestern Medical Center, Dallas, TX and Medical University of South Carolina, Charleston, SC. Patients or other Participants: Twelve human male umbilical cord blood samples and 7 human male testes were obtained from fetuses 14-21 weeks gestation. Male sex was verified by leukocyte genomic DNA SRY PCR. Interventions: None. Main Outcome Measures: Human male fetal INSL3 cord blood serum concentrations and testicular relative mRNA expression. Results: INSL3 serum concentrations during human male gestational weeks 15-20 were 2-4 times higher than published prepubertal male levels and were 5-100 times higher than previous reports of INSL3 concentrations obtained from amniotic fluid. Testicular fetal INSL3 mRNA relative expression was low from weeks 14-16, rose significantly weeks 17 and 18, and returned to low levels at week 21. Conclusions: These findings further support the role of INSL3 in human testicular descent and could prove relevant in uncovering the pathophysiology of cryptorchidism.

Sex determination from mesiodens of Indian children by amelogenin gene

Context:

The identification of sex is the first and the foremost step in forensic science. Teeth consist of enamel which is the hardest tissue available in the body, protector of DNA presents in pulp tissue at the time of exposure of tooth to adverse conditions. Teeth can be stated as a sealed box of mystery as it contains various human and bacterial DNA for molecular utilization.

Aim and Objective:

The aim is to determine sex from mesiodens on the basis of gene identification by the polymerase chain reaction (PCR).

Settings and Design:

Total number of sample was 8 human-extracted mesiodens. DNA was isolated and was subjected to PCR analysis with use of predesigned primers for amelogenin (AMEL) X and AMEL Y genes.

Results:

Isolation of genomic and mitochondrial DNA from mesiodens was successful in six samples (75%). In samples, quantity of DNA present was also calculated.

Conclusion:

Mesiodens are a good source of DNA and are a very useful tool in identification of sex using PCR analysis which was simple and effective. Hence, the procedure presented in the present study can be applied for extraction of DNA and identification of sex for forensic purpose.

Molecular sex identification of dry human teeth specimens from Sokoto, Northwestern Nigeria

BACKGROUND

The advent of molecular techniques has revolutionized the ability of scientists to estimate the sex of individuals. Forensic odontology plays an important role in establishing the sex of victims with bodies mutilated beyond recognition due to major disaster. The genetic difference between males and females is defined by the presence or absence of the Y-chromosome. The use of alphoid-repeat primers in sex estimation was first applied on dried blood. Generally, the X, Y alphoid repeats blind test attest to the accuracy of genetic testing, and also point the potential for occasional error in morphometric sexing.

AIM

To estimate genetic sex of dry human teeth specimens from Sokoto, Northwestern Nigeria, using polymerase chain reaction (PCR).

MATERIALS AND METHODS

A single-blind study of DNA analysis for sex estimation of nine dry human teeth specimens from Sokoto, Northwestern Nigeria, through PCR, using alphoid repeats primers, was undertaken.

RESULTS

The genetic sex of each group of the teeth samples were accurately (100%) identified. For each group of teeth, PCR Sensitivity = 100%, Specificity = 0%, Predictive value of positive test = 100%, Predictive value of negative test = 0%, False positive rate = 0%, False negative rate = 0%, Efficiency of test = 100%. Fisher's exact probability test P = 1. Z-test: z- and P values were invalid.

CONCLUSION

This study has demonstrated the successful use of alphoid-repeat primers in genetic sex identification of human dry teeth samples from Sokoto, Northwestern Nigeria. This is the first known study estimating the sex of human dry teeth specimens by means of PCR in Nigeria. There is need for further studies in Nigeria to complement the findings of this study.

Role of deoxyribonucleic acid technology in forensic dentistry

In the last few years, Deoxyribonucleic Acid (DNA) analysis methods have been applied to forensic cases. Forensic dental record comparison has been used for human identification in cases where destruction of bodily tissues or prolonged exposure to the environment has made other means of identification impractical, that is, after fire exposure or mass disaster. Teeth play an important role in identification and criminology, due to their unique characteristics and relatively high degree of physical and chemical resistance. The use of a DNA profile test in forensic dentistry offers a new perspective in human identification. The DNA is responsible for storing all the genetic material and is unique to each individual. The currently available DNA tests have high reliability and are accepted as legal proofs in courts. This article gives an overview of the evolution of DNA technology in the last few years, highlighting its importance in cases of forensic investigation.