Parental testing

The parentage is the result of a scientific process by which the relationship between people is to be found. The process is called paternity test because of the common use case in the current language.

Methods

The methods for paternity tests have been developed by the progress of science. There are, inter alia, the following methods:

  • For blood group tests the blood groups of the mother, the child and the alleged father to be determined. The known laws of inheritance include a number of combinations result from compelling.
  • In serological report more blood components ( HLA antigens and other proteins ) are drawn into the investigation.
  • When anthropological and hereditary biological opinion was (skin, eye, hair color, head shape, iris structure, for example ) to consider the likelihood of paternity with the help of inheritable physical features.
  • The DNA analysis provides the most advanced and safest method of descent tests; they can also be performed prenatally, as can be detected in the blood of pregnant women free fetal DNA.

Plausibility checks on the basis of visible characteristics

The assessment of the anthropological differences is the oldest method available. This is a plausibility check in the existing knowledge on parents and offspring is compared with known inheritance rules and statistics. This method can regularly a progeny does not rule out eventually, as parents phenotypically distinct genetic traits (phenotype and genotype) can inherit nevertheless, so that the child show visible features that are not visible in the parents. By phenotypic plasticity, including the influence of environmental and suffered in the course of life diseases, even dominant genes can be various degrees of seriousness.

  • Hair color - in hair color is dark brown dominant to blond, so that even dark-haired parents can have blonde children. Likewise, red hair are recessive, in which instead of the brown melanin the lighter pheomelanin forms the pigmentation.
  • Eye color - blue eyes are recessive, since a bright blue like in infants actually contains no pigmentation. On the inheritance of eye color at least three genes are involved, whose function is not yet fully understood.
  • Height - the attainable body size is dependent not only on the genetic constitution also from the diet, especially protein intake. Statistically probably is actually the average of mother and father plus / minus 6.5 cm for sons / daughters.
  • Skin color - the limited state of research on the genetic basis of skin color refers to the fact that most of the differences arise from variations of the receptors for the pigmented melanin. For Europeans, so far 18 genes have been identified that make a contribution, in Africans, there are populations that have none of these genes variations.

Especially the external features of a child often give the original reason to doubt paternity. The samples for the genetic basis, however, show that even large differences are unlikely, but do not provide a reason for exclusion. The coincidence of several major differences is unlikely, however, the intuitive notion of probability is partly deviate substantially from the known probability.

Process of elimination based on a blood group test

For blood group tests the blood groups of the mother, the child and the alleged father to be determined. It is then checked whether a common descendant of the mother and father could have the same blood group as the child. This method can exclude only in certain combinations paternity, but not confirm.

The inheritance rules to blood groups AB0 system are completely known - and in contrast to the Rh factor and the antibodies are spontaneously in all children in the first year of life pronounced, which are easy to detect by antibody screening. The tests for blood group AB0 system and Rhesus D are widespread, including a bedside test. In comparison with DNA analysis of blood group determination is cheaper and for adults can be the blood group easily by a blood free to bring in experience. The blood group of an unborn child can without risk to the pregnancy be determined because blood body of the child to a small extent are also present in the bloodstream of the mother and can be distinguished there - an intervention such as in prenatal genetic diagnosis is not necessary here.

Everyone has a genotype in the AB0 system with exactly two alleles from the totality of codominant allele A and allele B with the recessive allele 0 The genotype of a child forms from each exactly one allele of the mother's genotype and exactly one allele of genotype of the Father. A popularly adopted inheritance of phenotypic blood group, there is not a child of parents with blood type AB (genotype AB ) and 0 ( genotype 00) must either blood group A ( genotype A0) or type B blood (genotype B0) have. Other blood types are generated from these parents can not be configured ( here AB or 0). For other parents configuration can be by knowing the blood groups of grandparents often exclude some genotypes.

Paternity tests based on DNA analysis

Genetic fingerprinting allowed the identification of a person based on characteristics of the DNA. In the course of descent opinion one uses the rules of inheritance that in diploid human genome for each gene in each one allele from the father and the other must come from the mother. If problems occur in the DNA strands of the chromosome features that are not present in the parents, it can thus be excluded parenthood. Since there are a number of possible errors in the biological inheritance, including acquired during the lifetime of mutations that are included as part of the lineage report several features in DNA analysis and combined into a probability number of descent. Since the genetic fingerprint one focuses on areas that have a high degree of variability in the general population, DNA analysis can also confirm with a probability number parenthood.

For the parentage no coding sections are examined as a rule, only the regions between genes are analyzed (Repetitive DNA). Therefore, these DNA investigation within the meaning of the law becomes not as specially protected genetic testing, but the sampling in the child is an invasion of the personal rights. In Germany, therefore, the recovery of a lineage report was regulated by means of DNA analysis.

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