Recently, a new study covering nearly 10,000 people in Singapore has identified genetic variations which predispose people of different ethnic groups to certain medical conditions and adverse drug responses.
A gene, made up of DNA molecules, is the basic physical and functional unit of heredity. Human’s 200 years of study into our own genetics have borne an enormous amount of fruits in the medical field. In the past decades, we have identified hundreds of genes connected to a variety of diseases, including many types of cancer.
What does the study tell us?
The study characterised clinically significant genetic variation in an ancestrally diverse Asian population and highlighted diversity in risk profiles for dominant and recessive genetic disorders, capturing the common disorders among Asians missed by prevailing screening panels. The overall frequency of clinically actionable genes was comparable to European-centric cohorts, there were differences in concentration of disease burden, exemplified by the higher risk for familial hypercholesterolemia (FH) among Chinese in contrast to the higher risk for hereditary breast and ovarian cancer (HBOC) among European-descent populations. Meanwhile, disease risk and carrier burden varied even among Asian ancestry groups, driven by the distinctive prevalence of ancestry-specific recurrent variants.
Pharmacogenomics is the study of how an individual’s genetic makeup affects their response to drugs. The study also investigated the pharmacogenomics of a large cohort of Asian ancestries. It concluded that approximately one-fifth of individuals with a predisposition to a genetic disorder are at risk of therapeutic failure or life-threatening toxicity for drugs commonly prescribed to treat the disease. Thus, a substantial fraction of genetically susceptible individuals could benefit from pre-emptive pharmacogenomics to optimize their therapeutic treatments and avoid severe toxicities, indicating opportunities to forge more comprehensive clinical care by combining pharmacogenomics and genetic disease testing.
Finally, it’s important to say that it’s not lifestyle factors alone that contribute to a greater risk of developing certain diseases among different ethnic groups. The study highlighted the need to address disparities in existing knowledge by demonstrating the contrast in risk profiles of certain genetic disorders between European and Asian ancestry groups and the need for greater genetic testing among Asians.
What are the common diseases among particular ethnic groups?
There are several genetic conditions that are more common in particular ethnic groups due to the presence of specific genetic variations that are more prevalent in these populations.
- Sickle cell disease: This is a blood disorder that is more common in individuals of African descent. It is caused by a genetic mutation that affects the production of haemoglobin, the protein in red blood cells that carries oxygen throughout the body.
- Tay-Sachs disease: This is a rare genetic disorder that is more common in individuals of Ashkenazi Jewish descent. It is caused by a deficiency in an enzyme that breaks down a fatty substance called ganglioside, which accumulates in the brain and causes progressive damage.
- Beta thalassemia: This is a blood disorder that is more common in individuals of Mediterranean, Middle Eastern, and South Asian descent. It is caused by mutations in the genes that produce the beta globin protein, which is a component of haemoglobin.
- Cystic fibrosis: This is a genetic disorder that is more common in individuals of Northern European descent. It is caused by mutations in a gene called CFTR, which affects the production of mucus and causes problems in the lungs, pancreas, and other organs.
- Hemochromatosis: This is a genetic disorder that is more common in individuals of Northern European descent. It causes the body to absorb too much iron from the diet, which can lead to organ damage over time.
Currently, there are many more genetic studies on people of European and African descent than Asian descent. However, in recent years, more and more studies on Asian genetics are published in countries like China and Singapore. With more genetic research, doctors and pharmaceutical companies can better target treatment for people with a certain genetic predisposition to particular diseases. Couples could also get more thorough genetic counselling and be better prepared for their children’s health. With this study as one of the first, many more are expected to come in the near future.