基因與糖尿病 Genetics and Diabetes
Updated: Jan 15
形成一型糖尿病主要是因為身體出現抗胰島細胞的反應，令自身免疫細胞破壞胰島細胞，最後因胰島素生產不足而最終導致血糖上升。研究同時發現多個基因與一型糖尿病有關聯，而這些基因的功能大多數與免疫系統有關。 另一種糖尿病，「年輕早發型糖尿病（Maturity Onset Diabetes of the Young，MODY）」，是一種由基因突變引起的單基因糖尿病。「年輕早發型糖尿病」與一型糖尿病相似，患者多數在年輕時發病，但亦因這方面兩者病徵較為相似，導致年輕早發型糖尿病病人常被誤診為一型糖尿病，並接受一型糖尿病的治療方法，導致治療效果未能達致理想。
Each cell in the human body contains genes and around 20,000 of these are protein-coding. These genes are inherited from the parents and are similar to a blueprint since the human body will produce proteins and control its structure and functions based on this “blueprint.” Since there are variations among individual’s genes, they enable us to be different in appearance and physique.
Understanding Genes and Diabetes
As technology advances, human has been trying to encode this genetic blueprint and studying genes and diabetes and their relationship with related diseases. Evidence from studies show that if an individual’s direct relatives (e.g., parents, siblings) have Type II diabetes, they are up to 3 times more likely than others to get it later in life. Studies also find that some genetic variations in individuals may affect the development of the pancreas, the generation and secretion of insulin, and the insulin sensitivity of cells.
Currently, diabetes genetic studies have discovered over 100 genetic variations associated with Type II diabetes, and diabetes and its complications are caused by multiple genetic changes. However, not all genetic variations will induce disease instantly, other risk factors of diabetes also contribute to our well-being. In addition, studies from foreign countries find that among different races, their diabetes-related genes are also different. These variations can lead to different incidence of diabetes in different groups of people. Using Asia as an example, ⅕ of Chinese diabetic patients see onset of the disease before 40 years of age and it is probably associated with race-related genes.
Cause of Type II Diabetes
Type II diabetes results from genetic and variable risk factors. If an individual naturally has multiple high-risk genes and is also affected by adverse environmental factors (e.g. obese, smoking, etc.), plus a delay in diagnosis and treatment because the diabetic symptoms are not obvious, these factors will all increase the risk of developing diabetes. On the contrary, if one has a limited number of high-risk genes and cares about one’s health as well as aware of the risks, then this individual has a relatively lower chance of developing diabetes. Although genes are irreversible, variable risk factors (such as weight) can be changed to reduce the risk. Therefore, the earlier you know about your physical conditions, the better you can prevent yourself from developing diabetes.
True or False Type I Diabetes?
Type I diabetes is mainly due to the immune system attacking islet cells which will result in increased blood sugar due to the insufficient production of insulin. Studies also find that multiple genes are associated with Type I diabetes and the functions of these genes are mostly related to the immune system. Another subtype of diabetes, namely “Maturity Onset Diabetes of the Young (MODY)”, is induced by a single gene mutation.
Similar to Type I diabetes, MODY patients usually show onset symptoms from a young age, and also due to the similarity between these two types, young “MODY” patients are often misdiagnosed with Type I diabetes and receive therapies for Type I diabetes, causing unsatisfactory treatment results.
Understanding Precision Medicine
The study of genetic blueprints not only can analyze different types of diabetes, the genome can also reflect the effectiveness of drugs and associated reactions. In the past when we wanted to know the effectiveness of a particular drug on an individual, it took quite some time to observe its benefits and reactions, and only then would the type of drug and dosage be adjusted according to the situation.
However, with the help of genetic information, precise decisions can be made to avoid using drugs with poor or undesirable results, and we can personalize a precise medical regimen. We believe in the near future, medical staff can use genetic tests as a common practice to perform risk prediction for people who are at a higher risk of developing diabetes.
On the other hand, diabetes patients can be diagnosed with the correct type and/or subtype, their conditions can be better assessed, and a management regimen of precise treatment can be applied to reduce complications. For further information about genetics and diabetes, please seek professional medical advice and consult a doctor.