Autoimmune diseases refer to diseases where the body itself manifests an immune reaction to its own antigens, causing disease. In other words, it attacks its own tissues and organs causing pain, inflammation and other pathological manifestations affecting the quality of life.
It is estimated that around 50 million people suffer from one Autoimmune disease (AD: Autoimmune Disease), i.e. 1% of the total population of the planet.
“Today they have been recognized over 80 different autoimmune diseasesof which the most common are rheumatoid arthritis, type 1 diabetes, systemic lupus erythematosus, psoriasis, multiple sclerosis, autoimmune thyroiditis, celiac disease and others,” points out the Mrs. Eleni Komninou Rheumatologist, Director of Autoimmune Rheumatic Diseases Clinic Metropolitan General.
There are many hypotheses regarding the causes of autoimmune diseases, such as: genetic factors, viruses, bacteria, toxins, psychosomatic causes, etc.
The majority of autoimmune diseases are not “hereditary” in the classical sense of the term, such as e.g. Mediterranean anemia or cystic fibrosis, which are caused by mutations. But often in families that have members with autoimmune diseases, a predisposition is observed that other people in the extended family may develop an autoimmune disease.
Genetic diversity and predisposition
“Genetic variation in just 0.1% of the genome is responsible for the uniqueness and diversity of individuals and is responsible for genetic predisposition to disease. Two categories of DNA changes are responsible for genetic diversity: single nucleotide polymorphisms (SNPs) and copy number variations (CNVs).
The thorough study of SNPs has resulted in the identification of many SNPs associated with autoimmune diseases and explains the genetic predisposition observed in some individuals and families.
Mutations on the other hand are abnormal changes in the DNA sequence that lead to an abnormal gene and disease. The majority of individuals in the population have two normal copies of each gene. Mutated genes are rare. In contrast, polymorphisms resulting from SNPs and CNVs are very common. Both SNPs and CNVs and mutations are inherited.
But it is possible that they are new events (de novo) during gametogenesis, embryogenesis, as well as during cell division in the somatic cells of an individual.
Some people inherit a genetic code with mutations or changes in specific genes, i.e. DNA, that increase the risk of developing diseases. This does not mean that in every case they will be expressed and lead to disease.
The human (Homo Sapiens) genome has been 99.9% conserved during evolution. The genetic variation (genetic variation) in only 0.1% of the genome is responsible for the uniqueness and diversity of individuals and is responsible for the genetic predisposition to diseases, explains the doctor.
The fact that there is a clear link between genetic predisposition and autoimmune diseases is also reinforced by studies on monozygotic twins, where their genetic material is identical. It is observed that when one of the monozygotic twins gets sick, there is a high probability that the other will also get sick. It has been observed, for example, that in celiac disease, when one twin gets sick, the probability that the other will also get sick can reach up to 83%, which shows the strong influence of the genetic factor.
Association of genes and autoimmune diseases
About fifty, 49 to be exact, autoimmune diseases have been associated with 4,249 different genes.
From the study of monozygotic twins it has been established that in autoimmune diseases the genetic factor contributes on average 25% – 40%. Also, it has been found that the same genes or genetic regions are involved in many different autoimmune diseases and there are common triggers, meaning that the same person can suffer from different autoimmune diseases.
“Although, as presented above, genes and genetic changes have their importance, as is the case for all diseases, man is not only a prisoner of his DNA and genes. The deviation from the natural way of life and diet, as well as the burden from the “toxic load” in the environment where we live are the main causes of causing autoimmune diseases.
By shaping one’s lifestyle it is possible to influence the non-occurrence of an autoimmune disease to which one is genetically predisposed and to influence one’s health to a great extent”, concludes Ms. Komninou.
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