While the exact cause of keratoconus (KC) remains unknown, many studies have shown that genetics play a role in the development of the disease. A familial association appears to play a role in KC, and current literature indicates that there is less than a one in ten chance that a blood relative of a KC patient will also have the disease. While the chances of KC being passed down from relatives are low, there is still evidence that shows a person has an increased risk of developing KC if a blood relative also has the disease.
To understand the role that genetics plays in KC development, scientists have conducted multiple studies in hopes of identifying the exact genes associated with KC. There have been a handful of genes that have been identified and linked to KC, but the exact ways in which these genes influence KC development remains unclear. One theory is that KC is a monogenic disease, meaning that a single error in a single gene can cause the disease. In fact, there have been reports of large families with a high rate of KC. It is theorized that in these cases, a single gene abnormality was passed down through the family, causing multiple members to suffer from the disease. However, many other reports and studies indicate that KC is a much more complex disease and that there are small genetic variations in multiple genes in each affected individual. A popular theory combines both ideas: KC is a continuum, meaning that there are individuals whose disease is the result of a single gene mutation, and many more individuals whose disease is caused by environmental factors in combination with a large number of small effect genetic risk factors. Further research will have to be conducted to clarify the exact role of genetics in KC development.
While it is still unclear how exactly genetics contributes to the development of KC, it can be concluded that genetics does in fact play a role in KC development. If you have any family members with KC, it is important that you have regular eye examinations to monitor for the disease.
Source: Valgaeren H, Koppen C, Van Camp G, “A new perspective on the genetics of keratoconus: why have we not been more successful? Ophthalmic Genet 2017 Nov 7:1-17.