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Familias is a program for probability calculations when inferring paternity and identification based on DNA data. It is freely available from this homepage.

The familias program may be used to compute probabilities and likelihoods in cases where DNA profiles of some people are known, but their family relationship is in doubt. The program extends a previous program known as pater, in that multiple alternative pedigrees can be handled. Given several alternative family trees (or pedigrees) for a group of people, given DNA measurements from some of these people, and given a data base of DNA observations in the relevant population, the program may compute which pedigree is most likely, and how much more likely it is than others. Obviously, there are several other programs performing similar tasks. As far we know a distinguishing feature of familias is its ability to handle complex cases where potential mutations are accounted for, together with its ability to handle multiple pedigrees simultaneously. Familias does not co computations for linked markers; for such computations, you may consider FamLink.

Background

The familias program (and previously the pater program) has been developed by Petter Mostad and Thore Egeland, then at the Norwegian Computing Center, in cooperation with Bjørnar Olaisen, Margurethe Stenersen, and Bente Mevåg at the Institute of Forensic Medicine (RMI) in Oslo. The Norwegian Computing Center is a non-profit institute for applied research. The cooperation with RMI started in 1994, and the first version of the program was made in 1995. Several updates have been made since then, the latest in May 2010. The program is released freely.

Method

The simplest cases in which the familias program can be used are paternity cases, i.e., cases where one wants to determine whether a man is the father of a certain child. In general, one would have DNA data for the child, the mother, and the putative father. One would also need data bases with the frequencies for the observed alleles in the relevant population. Given this, the program will calculate the odds for the putative father being the real father.In such paternity cases, one may say there are two alternative hypotheses, i.e., two alternative pedigrees: One where the man is the father, and one where he isn't. The strength of familias is that it may calculate odds for any pair of alternative pedigrees. Thus, it may be used to calculate whether an uncle is indeed an uncle, whether two girls are indeed sisters, and so on. In fact, multiple different hypotheses may be handled.

In some systems used for human DNA typing, mutations are fairly frequent. If the possibility of mutations is not considered, one may mistakenly exclude a pedigree that turn out to be the correct one after considering all the data. The familias program has the ability to weigh the possibility of mutations against other evidence.

A number of other features, such as the possibility to adjust for kinship, are also included. See the documentation, and the program, for further details.

Using familias

The program may be downloaded here. A short tutorial, and a manual, are available.

The program downloadable above (Familias 2.0, actually identical to Familias 1.97) runs under Windows, and is intended for practical use in DNA testing labs. It is the result of many many years of cumulative development. A new version is now being developed at RMI. It will improve and modernize the program in may ways, for example it will be able to handle DVI situations. For further information about the new version, please contact Daniel Kling.

For research purposes, the core functions of Familias have now been made availiable in an R package. Please see the OpenFamilias pages.

If you have questions, please consult the Help pages.

Citing Familias

Egeland, Thore; Mostad, Petter; Mevåg, Bente; Stenersen, Margurethe: "Beyond traditional paternity and identification cases. Selecting the most probable pedigree." Forensic Science International Vol 110, Nr. 1, 2000.

Some other references

Egeland, Thore; Mostad, Petter: "Statistical Genetics and Genetical Statistics: a Forensic Perspective". Scand. Journal of Statistics, Vol 29, 2002.

Olaisen,B,  Stenersen, M  and  Mevåg, B: "Identification by DNA analysis of the victims of the August 1996 Spitsbergen civil aircraft disaster",  Nature Genetics Vol. 15, April 1997(402-405).

Familias validation

J. Drábek: Validation of software for calculating the likelihood ratio for parentage and kinship Forensic Science International: Genetics, Volume 3, Issue 2, Pages 112-118. (2008)

You may send comments to mostad@chalmers.se