Differences between the
X chromosome and
Y chromosome versions of the amelogenin gene (AMELX and AMELY respectively) enable it to be used in sex determination of unknown human samples.
AMELX's intron 1 contains a 6-base-pair deletion relative to
intron 1 of
AMELY. This can be detected at low cost using
polymerase chain reaction (PCR) of intron 1, followed by
gel electrophoresis. Two
bands of DNA, at 555 bps and 371 bps, are resolved if both the AMELX and AMELY versions of the gene are present (i.e. the sample is from a male) or one band of DNA, at 555 bps, if the AMELX version only is present (i.e. the sample is from a female). However, because of AMELY variation among individuals and populations, this method of sex determination is not 100% accurate. Mutation in regions of AMELY intron 1 commonly used as
primer annealing sites may disable PCR amplification. A 6bp
insertion to AMELY intron 1 results in an amplicon identical in length to that of AMELX. In some males AMELY may be deleted entirely. In any of these cases only one band is visualized during gel electrophoresis of PCR products, causing misidentification of the sample as female. Another study in India, however, found 5 of its 270 men studied (1.85%) possessed an AMELY deletion, terming them "deleted-amelogenin males" (DAMs). In response the authors suggested that while the amelogenin sex test may be accurate in general, other Y chromosome markers such as
SRY, STR, or 50f2 can be used for less ambiguous gender identification. In archaeology where DNA is too broken down to be analyzed by PCR,
Liquid chromatography–tandem mass spectrometry (LC-MS/MS) is used to directly detect the presence of the peptides corresponding to either version from tooth enamel samples. This method has been used on samples as old as the
Gravettian. == Clinical significance ==