Diagnostic Genetics
Genetic testing helps us to get to know ourselves, so our doctor can personalise our treatment.
Genetics and Diagnostics
Monogenic genetic diseases are caused by an alteration in the DNA sequence of a single gene, resulting in an alteration in the protein encoded by that gene. They are transmitted from generation to generation, from parent to offspring, and may or may not manifest themselves, following a Mendelian inheritance pattern.
More than 6000 monogenic diseases are known to mankind, with a prevalence of 1 case per 200 births. More than 10,000 diseases are believed to be monogenic in origin.
These diseases are caused by mutations in the nucleotide sequence of a gene, due to substitution, loss or gain of nucleotides.
A mutation can cause alteration of the amino acid sequence of a protein and thus can alter its conformation and function, resulting in a disease phenotype.
Therefore, the effect of a mutation depends on the nature of the DNA sequence change.
Monogenic diseases follow classical or Mendelian patterns of inheritance: autosomal inheritance (dominant or recessive) and sex-linked inheritance.
When the result obtained after genetic analysis gives evidence of mutations that are in themselves pathogenic, we can establish a molecular diagnosis based on the appearance of said mutation, giving the patient the status of carrier or sufferer of a certain disease. The assignment of one of these statuses depends on the dose and transmission characteristics of the genetic disease in question.
Genetic disease
Genetic disease is caused by an alteration of an individual's DNA. This alteration can affect a single gene, several genes, a chromosome, or several chromosomes. All diseases to a greater or lesser extent have a genetic component.
Genetic diagnosis provides insight into the genetic basis of a hereditary disease, and the information that can be obtained is necessary for decision-making in several aspects:
- Treatment: The result of a genetic study that can determine the most effective type of treatment for the pathology.
- Evolution and prognosis: a hereditary pathology can have different severities or developments depending on the mutation that caused it. Genetic diagnosis makes it possible to anticipate its manifestation so that it can be adequately prevented.
- Form of inheritance: A genetic alteration can be transmitted recessively, dominantly, depending on sex, or sporadically according to the association of risks inherited from our parents. Interpreting this aspect allows us to estimate the chances of it being transmitted to the individual’s offspring and whether it will manifest itself.
- Preventing the transmission of the pathology: Knowledge of the genetic basis of a pathology makes it possible to prevent its transmission to offspring, using prenatal or pre-implantation genetic diagnosis methods.
- Family study: The implications of a genetic test are also important for the direct relatives of those affected, so it is advisable to assess the convenience of extending the testing to other members of the family. It is possible that a genetic alteration manifested in a second, third, or fourth degree relative may also manifest itself in other branches of the family.