'Junk DNA' plays role in face shape

Regions of the genome that do not code for proteins have
been found to shape facial features, research at the Lawrence Berkeley National
Laboratory, USA, has shown.

The team identified more than 4,000 regions of DNA in noncoding
areas, often dubbed 'junk DNA', that affect the shape of the skull or size of
the nose.

'We're trying to
find out how these instructions for building the human face are embedded in
human DNA', Professor Axel Visel, who led the study, told BBC News. 'Somewhere in there must be that blueprint
that defines what our face looks like'.

The study looked at 3D models of developing mouse embryos
and identified transcriptional enhancers - lengths of DNA that affect which
genes are switched on or off - that were active during facial development.

Researchers saw subtle and consistent changes to the length
and width of the faces after deleting three of these enhancers in mice when
comparing their CT scans with those from normal mouse embryos.

Although these experiments were carried out on mice, humans
have many of the same enhancer regions, so these results may help researchers
gain a greater understanding of facial birth defects such as cleft lip or
palate.

'Our
results also offer an opportunity for human geneticists to look for mutations
specifically in enhancers that may play a role in birth defects, which in turn
may help to develop better diagnostic and therapeutic approaches', said Professor
Visel.

Speaking to The
Guardian, Professor Peter Hammond at University College London's Institute
of Child Health, who was not involved in the research, said: 'There are many
genetic conditions where the face is a first clue to diagnosis, and even though
the facial differences are not necessarily severe the condition may involve
significant intellectual impairment or adverse behavioural traits, as well as
many other effects'.

The study was published in Science.