The Paternity test allow to establish if a man is or not a biological father of the other individual. Currently the exam is made through the analysis of highly variable DNA regions, different for length from individual to individual and namely micro-satellites (STR); because each of us inherits a half of our genetic heritage from father and half from mother, the comparison of own type of micro-satellites with that of father (and eventually of the mother) establish the paternity attribution or exclution.
In the Fig 1 it has been considered only 5 micro-satellites (normally 9-15 STR are analyzed) with a variable length, indicated by a letter (different letters for different lengths); in each individual, a micro-satellite, like a gene, is present in double copy. The profile of alleged father is A/B-C/D-E/F-G/G-H/I, that of the mother is D/B-J/E-F/K-L/M-N/G; the son which has inherited half of the genetic heritage from the father and half from the mother has a profile B/D-D/J-F/F-G/L-I/N. This result suggests with a 99,99% probability that the alleged father is a biological father (attribution of paternity).
Fig.1 – Attribution of paternity
In the Fig.2 the profile of the alleged father is A/B-C/D-E/F-G/G-H/I, that of the mother D/B-J/E-F/K-L/M-N/G; the son have a genetic profile C/D-K/J-G/F-P/L-E/N, that is different from the father for all STR; this result indicates the alleged father isn't a biological father (exclusion of paternity).
Fig.2- Exclusion of paternity
Usually the test is performed comparing the genetic profile of three individuals: alleged father, son and mother; if the mother isn't available, it can be made only on the son and alleged father.
Legal paternity test
In order that the paternity test has a legal soundness it’s necessary of:
- valid identification document (ID, passport, driver licence, etc) of the individuals who perform the test.
- authorization for children or individuals under legal protection of the/those who has/
have the parental authority or legal protection.
- for adults, signed informed consent about of a way and aims of sampling and analysis.
It’s not necessary a simultaneous sampling for all individuals involved.
The paternity test results are available after 20 days from the withdrawal.
DNA extracted from peripheral blood lymphocytes (in tubes with EDTA) or buccal swab (baby or child)