I-MAG STS Corporation
The legendary actress Elizabeth Taylor was famed for, among other things, a
double row of eyelashes and violet eyes. We are not knowledgeable about the
genetics of eyelashes, but in the human genome the DNA associated with eye
color is the Oculocutaneous Albinism Type II gene on the long arm of
chromosome 15. OCA2 encodes the tersely but unimaginatively named P
protein which is believed to be an integral membrane protein involved in small
molecule transport, specifically tyrosine. Tyrosine is a precursor of melanin.
One mutation of OCA2 is found in almost all blue-eyed people, and it is
conjectured that all blue eyed humans share a single common ancestor. Prior
to some time between 6,000 and 10,000 years ago, we were all brown-eyed.
The most common OCA2 mutation is a large deletion in the gene, which is
found in many affected individuals of sub-Saharan African heritage: blond or
light brown hair; creamy white skin, light-colored eyes, and problems with
vision. The OCA2 gene is in a region of chromosome 15 where deletions are
associated with Angelman's syndrome (UBE3A also involved) as well as
Prader-Willi syndrome.
Fellow blue-eyed mutants take heart: it is evidently much less important how
much melanin is manifested in one's eyes than what one does about what those
eyes see.