Uncommon illnesses showing up more frequently: An in-depth examination of the locations and factors contributing to their increased prevalence
In various parts of the world, rare diseases are becoming a growing area of interest, particularly in regions where consanguineous marriages are common. These unions, where partners are closely related, such as first cousins, are prevalent in Arab nations and certain communities in Brazil. This practice, while culturally significant, contributes to the higher incidence of rare diseases in these regions.
One such region is Saudi Arabia, which ranks among the countries with the highest incidence of consanguineous marriages globally. This, in turn, leads to a high prevalence of thalassemia, an inherited blood disorder, within the kingdom. Saudi Arabia has seen a boom in human genetics research over the past decade, with researchers like Fowzan Alkuraya and his colleagues at King Faisal Specialist Hospital and Research Centre (KFSHRC) making significant contributions.
The Arab Pangenome, a recently published genetic research, aims to address the disparity in understanding genetic risk factors among different populations. This research could potentially provide valuable insights into the increased prevalence of rare diseases in consanguineous communities.
Another driver of rare disease prevalence is the founder effect, where a small, isolated population amplifies variants that were rare globally. This is evident in a small, remote town in Brazil called Serrinha dos Pintos, where a high rate of consanguineous marriages has led to the prevalence of a rare condition called Spoan syndrome, which affects the nervous system and gradually weakens the body.
Consanguineous marriages are a primary driver of recessive genetic disorders, including congenital heart diseases, renal diseases, and rare blood disorders. Studies have shown that many new mutations originate in sperm, and their frequency increases with the father's age. This dynamic, combined with the common practice of consanguineous marriages, contributes to the high incidence of rare diseases in these communities.
In an effort to combat this, Abu Dhabi's Department of Health recently established a policy requiring engaged couples to get genetic testing done before marriage. This proactive approach could potentially reduce the burden of rare diseases in the region.
However, it's important to note that the burden of rare diseases is particularly heavy in low- and middle-income countries due to inadequate healthcare infrastructure. This underscores the need for continued research and policy changes to address this issue on a global scale.
In contrast, some countries in Europe have banned cousin marriages to prevent health issues associated with these marriages, such as Norway, Sweden, and Denmark. Yet, the biology of rare diseases can sometimes reveal insights that lead to treatments for much larger patient populations. For instance, the development of Amgen's drug, Evenity, for osteoporosis, was influenced by the understanding of the biology of rare diseases.
As we delve deeper into the complex genetic causes of rare diseases, long-read sequencing will be crucial for identifying new drug targets. This could potentially lead to breakthroughs in the treatment and management of rare diseases, benefiting not only affected communities but also the broader medical community.
