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Genetics

Origin unveiled

Company creates software that makes paternity tests more accurate

MIGUEL BOYAYANAnswer quickly: what do Pelé, Mick Jagger and Renan Calheiros (Senator from the State of Alagoas) have in common? Easy: the three of them had to take paternity identification tests to prove they had fathered a child out of wedlock. The soccer king had to admit that he had fathered Sandra Regina Machado, from Santos, who died last year at the age of 42. The British rock star acknowledged his paternity of 8-year old Lucas, the result of a brief fling with TV presenter Luciana Gimenez when Jagger was touring Brazil for the Bridges to Babylon concert, in 1998. The former Senate chairman admitted that in December 2005 he had fathered the daughter, now three years old, of journalist Mônica Veloso. The DNA tests for proof of paternity were first used in the late 90s and they have already helped to unveil the origins of many people. Thanks to the efforts of a Brazilian biotech company, these tests have become much more reliable. Genomic Engenharia Molecular, based in the city of São Paulo, created a web-available computer tool for its clients. This tool will enable the clarification of complex paternity cases in which the alleged father is dead.

To understand the advances made possible by Genomic, which was established in 1991, one must first learn how DNA-based paternity tests are conducted when the parents are alive. The first step is to draw blood samples from the mother, the child and the alleged father. The next step is to extract the DNA from the leucocytes, the only blood cells that contain genetic material. A comparison is then made of the genetic material of the three parties. It must be kept in mind that DNA, deoxyribonucleic acid, is the source of the genetic information inherited from the parents and transmitted to the offspring. This information is found in the chromosome, at positions referred to as loci. Each locus has two or more alleles (one of the various forms of a gene), one of which comes from the mother and one from the father. The paternity test analyzes a specific number of loci and their respective alleles, which are similar in people with blood ties, and tend to be different in individuals who have no blood relationship.

The paternity test is simpler when the alleged father is alive, because the laboratory responsible for the identification has the genetic material of the parties involved and can therefore compare the loci and the alleles. Because of reliability issues, the laboratories analyze several loci and generate a paternity ratio for each one, taking into account the frequency of the alleles in the Brazilian population. They then calculate the accumulated paternity ratio, which is the result of the multiplication of the ratios of each locus. This is how the laboratories are able to specify how many times the investigated man has the chance of being the biological father of the given child, in comparison to another man chosen at random from the population. The final step is to convert this ratio into a probability that indicates the chance that a given individual is the biological father of another individual.

However, these calculations are much more complex when the alleged father is dead. “It is necessary to rebuild the genotype of the deceased man, but it isn’t always easy to extract DNA from corpses and the cost of analyzing skeletal bones is very high. Not to mention that the deceased may have been cremated,” explains physician and biochemist Martin Whittle, managing partner of Genomic. The expert explains that paternity tests of an alleged father who is dead or missing are quite common when a wealthy man dies and is survived by an illegitimate son or daughter interested in claiming a share of the inheritance. In these cases, the solution is to collect samples from the family members of the missing or dead father, such as his parents, siblings or biological offspring, who all share the same genetic material, and, based on this information, try to reconstruct the DNA of the deceased. “Labs can genotype the parties involved but they don’t know how to conduct the paternity probability calculation because there aren’t any standard mathematical formulas to define this ratio when the alleged father is deceased,” says Whittle. He adds that the only software – created by a Norwegian institute – that allows these calculations to be worked out is user-unfriendly and complicated.

To develop these formulas, Genomic obtained funding from FAPESP’s “Programa de Inovação Tecnológica em Pequenas Empresas/Pipe” (Program for Technological Innovation at Small Companies). The funds were to be used specifically to develop software and to purchase servers. In addition, Genomic entered a partnership arrangement with Supremum, a consulting firm from São Paulo specializing in mathematical and statistical models, and with a group of researchers from the Mathematics and Statistics Institute of the University of São Paulo, who used the Bayes network concept. These networks, based on a theorem proposed by British mathematician Thomas Bayes in 1763, are a reality representation model that works with uncertain and incomplete knowledge. The first presents deficient data, which may be inexact, partial or merely an approximation of reality – precisely the case of the analysis of a deceased person’s DNA. After completing these calculations, the next step taken by Genomic was to create a computer tool and make it available on its website for those interested in this issue.

The client’s lab technicians get a password that gives them access to GenomiCalc’s home page (http://genomicalc.com.br); they create a profile for the test, defining how many people will be tested and what their kinship is with the person being investigated. The technicians then add data about the genetic material of each person, specifying the number of alleles of each locus that is to be analyzed. From this point onward, the site itself does all the calculations and provides the paternity ratio and the probability. “One of the advantages of our software, the first of its kind to be available on the Internet, is that it can do the calculations with any configurations of individuals related to the alleged father,” points out Whittle.

“Our potential clients are the Brazilian and foreign laboratories that work with paternity tests, as well as government entities.” The interested parties pay for each test in order to have access to the software, or pay a subscription fee which is good for a set period of time. The yearly fee costs R$ 8 thousand and the subscriber is entitled to conduct one hundred calculations a month.

The Project
Computer analysis of genetic material to establish paternity  (nº 02/07887-6); Modality Programa Inovação Tecnológica em Pequenas Empresas (Pipe); Coordinator Martin Ritter Whittle – Genomic; Investment R$ 382,883.00 and US$ 37,700.00 (FAPESP)

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