It's important to understand eye color is determined by the pigmentation of the iris, a structure surrounding the pupil.
This pigmentation helps regulate the amount of light entering the eye and can range from very light blue to dark brown. It's essential to remember that eye color is often categorized as blue, green/hazel, or brown, with brown being the most common worldwide. The amount of melanin stored in the iris is determined by various genes involved in melanin production, transport, and storage.
Researchers have made significant progress in understanding the genetic basis of eye color. More than 150 genes have been identified as influencing eye color, with some discovered through studies of genetic disorders and others through genomic studies of animals. It's important to note that while some genes play a major role in determining eye color, others have a smaller contribution.
For instance, there are two genes on chromosome 15 that play major roles in determining eye color. The OCA2 gene codes for a protein called P protein, which affects the amount and quality of melanin stored in the iris. Genetic variations in this gene can result in lighter eye colors. Another important gene is HERC2, which controls the expression of OCA2. Variations in this gene can also impact the production of P protein and contribute to differences in eye color.
Additionally, several other genes, including ASIP, IRF4, SLC24A4, SLC24A5, SLC45A2, TPCN2, TYR, and TYRP1, are thought to play smaller roles in determining eye color. These genes likely interact with OCA2 and HERC2 to collectively influence eye color.
Understanding how eye color is inherited can be quite fascinating!
The inheritance pattern for eye color is complex because of the multiple genes involved.
While it's often thought that a child's eye color can be predicted by looking at the color of the parent's eyes, the reality is that the combination of genes can lead to unexpected eye colors in children.
A child’s eye color depends on the pairing of genes passed on from each parent, which is thought to involve at least three gene pairs. The two main gene pairs geneticists have focused on are EYCL1 (also called the gey gene) and EYCL3 (also called the bey2 gene).
The different versions of genes are known as alleles. The "bey" gene has one allele that results in green eyes and another allele that results in blue eyes. The "bey2" gene has one allele for brown eyes and one for blue eyes. The allele for brown eyes is the most dominant and always overrides the other two alleles, while the allele for green eyes is dominant over the allele for blue eyes, which is always recessive. Therefore, even if parents have the same eye color, they can still have a child with a different eye color.
For instance, if both parents with brown eyes pass on a pair of blue alleles to their child, the child will have blue eyes. However, if one of the parents passes on a green allele, the child will have green eyes, and if a brown allele is present, the child will have brown eyes regardless of the other alleles present.
You can think of eye color as a beautiful mystery!
While it's true that two parents with blue eyes can have a child with brown eyes, or that grey or hazel eyes can appear seemingly out of the blue, the explanation lies in modifier genes, other genes related to eye color, and genetic mutations. These factors all play a part in the fascinating variability of eye color. Scientists are still exploring how these elements contribute to the wide range of eye colors we see.
See you soon in one more such fascinating blog 🙌🤍
Comments