In this study we have established a simple, accurate and widely
applicable method for determining the sex of primate DNA samples by
using triple primer PCR of a small region of the UTX/UTY gene. The ubiquitously transcribed tetratricopeptide repeat protein gene (UTX/UTY) is located on the X and Y chromosomes and our analysis identified a region in the human UTY having
the highest identity to the mouse Y chromosome. Due to the high
conservation of this region the triple primer PCR setup works in all
primate species tested. Furthermore, the method contains an internal
positive control (the shared primer), but should always be tested in
samples of known sex before actual analysis is carried out. Also, it
may be necessary to perform species specific optimization of annealing
temperature and/or primer concentrations prior to analysis.
Since the nature of the Y chromosome allows deletion of many
regions, it can be expected that with an increased number of
individuals tested deletion of UTY might be found in low frequency (as
reported for amelogenin-Y ).
Furthermore, primer region mutations may result in non-identification
of males due to PCR failure, which are known in the amelogenin system [9-11]. Generally, non-identification of males may result from non-amplification of the Y fragment and it has been argued 
that all "females" (XX or XY with no Y amplification) should be
analysed with at least two independent sex tests. It is now possible to
combine the analysis of amelogenin, SRY and UTX/UTY in parallel for
most primate species, thereby obtaining reliable sex determination
and this study) using independent PCR runs. Given the low amount of DNA
usually obtained from non-invasive sampling, the optimal approach for
molecular sexing would be to run a single multiplex PCR analysis, but
such a protocol has not been developed yet.