Eye color is determined as a polymorphism and polygenic trait. Brown is the most common eye color in the world, accounting for about 79%, blue eye color for about 8–10%, hazel for 5%, and green for 2%. Rare‐colored eyes include gray and red/violet. Different factors are involved in determining eye color. The two most important factors are the iris pigment and the way light is scattered from the iris. Gene expression determines the iris pigmentation and how much melanin is present in the eye, which is the number of melanin subunits that identify eye color. The genes involved in the pigmentation of single‐nucleotide polymorphism (SNP) have a significant role; and even some genes are included only in the eye color through SNP. MicroRNAs also affect melanocyte synthesis, which is usually affected by the downregulation of essential genes involved in pigmentation. In this study, we assess the biochemical pathways of melanin synthesis, and the role of each gene in this pathway also has been examined in the signaling pathway that stimulates melanin synthesis.
Ectodermal dysplasia (ED) syndrome is a rare genetic disease that involves a heterogeneous group of hereditary disorders that occur as a result of mutations in genes that code for development of fetal ectoderm and lead to numerous disorders. Defects in the development of the ectoderm cause symptoms in tissues derived from the ectoderm layer, such as skin, nails, hair, and teeth. Because many pathways are involved in the development of the ectoderm, there are mutations in many genes that cause ED. Owing to the heterogeneity of ED, there are different types of the disease that have different symptoms. These symptoms include sparse hair, abnormal or missing teeth, nail dystrophy, lack of sweating owing to the absence of sweat glands, and cancer. In this review, in addition to discussing the role and pathway of each of the genes involved in ED, the incidence of cancer in these patients, diagnostic methods and differentiation from other similar diseases, and the treatments currently being performed for ED are discussed.
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