Genetic tests help us to know ourselves better, so our physician can personalize the treatment
Genetics and Diagnostics
Genetic diseases classified as monogenic diseases are caused by disturbances in the DNA sequence of a single gene, giving rise to an alteration in the protein encoded by that gene. These are transmitted from generation to generation, in the offspring, whether they become apparent or not, according to a Mendelian inheritance pattern. Over 6,000 monogenic diseases are known, and their prevalence is one case in every 200 births. It is believed that over 10,000 diseases are of monogenic origin. These diseases arise because of mutations in the nucleotide sequence of a gene, due to the replacement, loss or gain of nucleotides. A mutation may bring about an alteration in the amino acid sequence of a protein, and may therefore alter its structure and its function, giving rise to a disease phenotype. Therefore, the effect of a mutation depends on the nature of the change in the DNA sequence.
Monogenic diseases follow classic or Mendelian inheritance patterns: autosomal inheritance (dominant or recessive) and gender-related inheritance.
When the result obtained after genetic analysis evidences mutations which are pathogenic in themselves, we can establish a molecular diagnosis based on the appearance of that mutation, conferring on the patient the status of carrier or sufferer, according to the dose and the transmission characteristics of the genetic disorder in question.
Genetic disorders are caused by alterations in the individual’s DNA. This alteration may affect a single gene, several genes, a chromosome or several chromosomes. All diseases have a genetic component to a certain extent.
Genetic diagnosis enables us to find the genetic basis of a hereditary disease, and the information that may be obtained is necessary for the making of decisions in several aspects:
- TREATMENT: The result of a genetic test can determine the most effective type of treatment for the pathology.
- PROGRESSION AND PROGNOSIS: A hereditary pathology may have a different progression or seriousness, depending on the mutation causing the same. Genetic diagnosis enables us to anticipate its appearance and to take steps for its prevention.
- FORM OF INHERITANCE: A genetic alteration may be transmitted recessively or dominantly, gender-dependently, or sporadically due to the association of risks inherited from our parents. Interpreting this aspect enables us to estimate the probability of it being transmitted to our offspring and of it becoming evident.
- PREVENTING TRANSMISSION OF THE PATHOLOGY: Knowledge of the genetic basis of a pathology enables the prevention of its transmission to the offspring, by using prenatal or preimplantational genetic diagnostic methods.
- FAMILY SCREENING: The implications of a genetic screen are also important for the direct relatives of those affected; it is therefore advisable to consider the expediency of extending it to other members of the family. It is possible that a genetic alteration appearing in a second-, third- or fourth-degree relative may also appear in other branches of the family.