Reasons for different types of tests performed:
Paternity: Maintenance, birth certificate, identity documents, confirmation.
Maternity: determine if a child was swopped at birth, identity documentation.
Parentage test: immigration
Kinship: deceased estate, cultural reasons, find a relative after many years, sibling relatedness
Y-chromosome: genealogy, male relatedness, relationship of deceased male figure
The scientific accuracy of paternity test interpretations depends on the quality, quantity and reliability of the relevant information used in the assessment. DNA analysis uses short tandem repeat loci which are abundant in the human genome. Each locus contains alleles. One set of alleles is inherited from each parent. It is therefore important that both the parents are tested during a paternity test as one allele is first allocated to the mother and the remaining allele is allocated to the alleged father. If the alleged father
DNA (deoxyribonucleic acid) is located throughout the human body and is identical in all cells.
A person inherits 50% of the chromosomal DNA from one parent and the remaining 50% from the other parent. Therefor the samples of the mother as well as the father are required for precise results. The alleles from the child’s DNA profile are allocated to the mother first and the remaining set of alleles allocated to the father. It can happen that the alleged father is falsely included as the father of the child when the test is done on only the alleged father and the child (See article: The importance of including maternal profiles in paternity testing – three cases of possible false inclusion with duo-only testing. Y. Harris, D. Welgemoed. Medical Technology SA Vol 32 Number 2 2 December 2018)
This is to determine if a mother is the biological mother of a child. This could be for birth certificates, estate, confirmation of maternity, medical aid, hospital switches, adoption reunification. Genetic material of an alleged mother and child is analysed to determine the probability that the alleged mother is the biological mother of the child. The sample of the alleged mother and child are needed. If the alleged mother does not possess these genes, then she is excluded (ruled out) as the biological mother of the child and the probability of maternity will be 0%. If the alleged mother does possess these genes, then she is not excluded (not ruled out) as the biological mother and the probability of maternity will usually be more than 99.0%.
Test when the mother is deceased.
When the mother is deceased, the legal guardian of the underage child must give permission for a test to be done on the underage child.
This test can be done on any alleged family members to determine the potential relationship between individuals. This is used to conclude estate matters, deceased relatedness, confirm relative status,
This test determines whether individuals share the same biological parent. This test is performed where the alleged parent/s are not available for testing and a DNA profile of the alleged siblings can be performed to determine whether two individuals do in fact share the same biological parent/s. Statistical calculations are used to generate a likelihood ratio value which determines the most likely hood of the relationship between the individuals tested.
Grand parentage Testing
In a case where the alleged father/mother is not available for testing, a DNA profile Grand parentage Testing can be performed to investigate the likelihood that they are the biological grandparents of the grandchild. It is recommended to test both grandparents in order to obtain the most conclusive results.
The Y-chromosome profiles are used to follow the paternal/male lineage. All the sons of a man will have the same Y-chromosome profile. Full brothers, paternal half-brothers, male children of brothers (paternal cousins), etc. will all have identical Y-chromosome profiles, indicating that they are from the same male lineage.
Twin Zygosity Testing
Twin zygosity testing is performed to determine if twins are identical (conceived from one fertilized egg which splits into two embryos early in development) or fraternal (conceived from two different eggs and sperm). Identical twins will have exactly the same DNA profile, whereas fraternal twins will have different DNA profiles, sharing only some of their DNA.
Fully qualified, fully trained personal.
Registered medical laboratory.
Registered with HPCSA.
SANAS accredited laboratories.
ISO accredited laboratory
The importance of including maternal profiles in paternity testing – three cases of possible false inclusion with duo-only testing. Y. Harris, DJ. Welgemoed. Medical Technology SA Vol 32 Number 2 2 December 2018.
Nucleotide sequence analysis to identify a one-step mutation in a STR DNA profile during paternity testing at locus D7S820. Y. Harris, DJ Welgemoed, A Kotze et al. The Journal of Medical Laboratory Science and Technology South Africa. Vol. 1, No. 3, August 2019.
Interpretation of results
Twenty-three markers as well as an amelogenin (sex-determining) marker are used in the kit.
Exclusion: Three or more mismatches between child and parent will exclude the parent as the parent of the child. The probability of paternity will be 0%
Non-exclusion: this means that the parent is not excluded as the parent of the child. Internationally, a probability of 98% and upwards is taken as an inclusion. One or two mismatches is taken as a mutation and still seen as an inclusion.