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Subject: [GENEALOGY-DNA] PubMed abstract: autosomal STRs in kinship analysis
Date: Fri, 1 Sep 2006 11:56:06 EDT

The PCR kit mentioned in the abstract uses the 13 CODIS markers, the same set
commonly used in paternity testing labs and by DNA Tribes. The abstract shows
how much more difficult it is to identify first cousins (third-degree
relatives, who share 1/8th of their DNA on the average). If there are only two people
tested, 123 markers only get you a 90% chance of detecting a first-cousin
relationship. However, the inclusion of more family members helps considerably.

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Hum Biol. 2006 Feb;78(1):1-8.

STR markers for kinship analysis.

Wilkening S, Chen B, Hemminki K, Forsti A.

Department of Molecular Genetic Epidemiology, German Cancer Research Center
(DKFZ), Heidelberg.

The analysis of short tandem repeats is a widely used method to estimate
relatedness between closely related populations or individuals. The AmpFlSTR PCR
Amplification Kit has 15 highly variable autosomal markers of tetranucleotide
repeats and is principally made to identify individuals and first- or
second-degree relatives. However, in many studies one is searching for individuals who
are related through more than one generation. We wanted to test whether the
amplification kit can also be used to identify more distantly related
individuals. Therefore we compared 16 different methods that calculate genetic distance
with regard to each method's ability to cluster more distantly related
individuals from two test families. Among all the tested methods Nei et al.'s (1983)
DA distance performed well in clustering family members within a group of
unrelated individuals for a broad range of scenarios. However, second-degree r
elatives were difficult to cluster with any of the examined methods when other
family members were absent. With a simulation we further estimated how many
markers would actually be needed to detect a certain degree of relatedness.
According to this simulation, one would need at least 123 independent microsatellite
markers to detect third-degree relatives with 90% probability. In conclusion,
the 15 STR markers in the amplification kit are suitable for detecting only
very closely related individuals or entire families.

PMID: 16900878 [PubMed - indexed for MEDLINE]

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