![handle is hein.journals/injlegame128 and id is 1 raw text is: Int J Legal Med (2014) 128:1-9
DOI 10.1007/s00414-013-0847-2
(>RIG[NAL ARTICLE
Comparison of southern Chinese Han and Brazilian
Caucasian mutation rates at autosomal short tandem repeat
loci used in human forensic genetics
Hongyu Sun Sujuan Liu Yinming Zhang-
Martin R. Whittle
Received: 4 December 2012 /Accepted: 5 March 2013 /Published online: 3 April 2013
C Springer-Verlag Berlin Heidelberg 2013
Abstract The short tandem repeat (STR) loci used in hu-
man genetic studies are characterized by having relatively
high mutation rates. In particular, to ensure an appropriate
evaluation of genetic evidence in parentage and forensic
analyses, it is essential to have accurate estimates of the
mutation rates associated with the commonly used autoso-
mal and sex chromosome STR loci. Differences in STR
mutation rates between different ethnic groups should also
be determined. Mutation data from two laboratories working
with different ethnic groups were extracted from many
meiotic transmissions ascertained for 15 autosomal STR loci
currently used in forensic routine. Forty-five thousand and
eighty-five trios were checked for the biological consistency
of maternity and paternity through the analysis of a mini-
mum of 15 loci. Mutations were scored as paternal, mater-
nal, or ambiguous according to the most parsimonious
Hongyu Sun and Sujuan Liu contributed equally to the article.
Electronic supplementary material The online version of this article
(doi:10.1007/s00414-013-0847-2) contains supplementary material,
which is available to authorized users.
H. Sun
Shanghai Key Laboratory of Forensic Medicine,
Institute of Forensic Science, Ministry of Justice,
Shanghai, People's Republic of China
H. Sun S. Liu - Y. Zhang
Faculty of Forensic Medicine, Zhongshan School of Medicine,
Sun Yat-sen University, Guangzhou, People's Republic of China
M. R. Whittle ( )
Genomic Engenharia Molecular, Rua Itapeva 500/SAB,
01332-903 Sao Paulo, Sao Paulo, Brazil
e-mail: mwhittle@genomic.com.br
explanation for the inconsistency, using always the least
requiring hypothesis in terms of number of repeat differ-
ences. The main findings are: (a) the overall mutation rate
across the 15 loci was 9.78 x 10 4 per gamete per generation
(95 % CI-9.30 x 10 4-1.03 x 10 3), and with just 48 (out of
1,587) exceptions, all of the mutations were single-step; (b)
repeat gains were more frequent than losses; (c) longer
alleles were found to be more mutable; and (d) the mutation
rates differ at some loci between the two ethnic groups.
Large worldwide meiotic transmission datasets are still
needed to measure allele-specific mutation rates at the
STR loci consensually used in forensic genetics.
Keywords STR loci Mutation rate Parentage testing
Introduction
Mutation, besides being the most important evolutionary
driving force [1], is central to many biological phenomena
such as cancer and is also a factor sometimes of
underestimated importance in forensic genetics. In this par-
ticular field, both germinal and somatic mutations can be a
source of erroneous inferences either in kinship analysis or
in identification [2]. One of the reasons that short tandem
repeat (STR) loci, also known as microsatellites, remain the
markers of choice in forensic genetics is that they are highly
polymorphic, and this feature reflects their relatively high
mutation rate. This is due to their molecular architecture,
which makes them especially prone to a specific type of
mutation: the addition or subtraction of a repeat unit, com-
monly attributed to DNA polymerase slippage [3-5], during
which the nascent DNA strand and polymerase transiently
' Springer](ViewImageLocal?handle=hein.journals/injlegame128&div=1&collection=&method=preview&ext=.png&size=3)
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