PAX6 is widely expressed in the central nervous system. Heterozygous PAX6 m
utations in human aniridia cause defects that would seem to be confined to
the eye(1). Magnetic resonance imaging (MRI) and smell testing reveal the a
bsence or hypoplasia of the anterior commissure and reduced olfaction in a
large proportion of aniridia cases, which shows that PAX6 haploinsuffiency
causes more widespread human neuro developmental anomalies.