What is Genetics?

The study of genetics allows us to understand what exactly happens in the cell cycle, (replicate our cells) and reproduction, (meiosis) of living beings and how it can be that, for example, between human beings are transmitted biological characteristics genotype (content of the specific genome of an individual in the form of DNA), physical characteristics phenotype, appearance and even personality.

The main object of study of genetics are the genes, formed by segments of DNA (double strand) and RNA (single strand), after the transcription of messenger RNA, ribosomal RNA and transfer RNA, which are synthesized from DNA . DNA controls the structure and functioning of each cell, with the ability to create exact copies of itself, following a process called replication, in which DNA replicates.

The Human Genome Project, created in 1990, aimed to decipher the genetic code of the human being, which was completed in 2000. This research project has shown that there is 0.1% genetic variability among people. This variability is mainly due to polymorphisms of a single nucleotide (SNP of the English Single Nucleotide Polymorphism) that consist in the change of one nucleotide for another in the genome sequence, having been proven that many of these genetic polymorphisms may have pathogenic implications.

The risk of suffering from a disease is due to the combination of genetics and the environment (diet, lifestyle, etc). Depending on the disease, the influence of genetics in suffering it or in treating it can be very large or residual. There are diseases where genetics is the cause at 100%, while others do not have (or have yet to be proven) a relationship with the patient’s genes.

In genetic tests what is valued is the risk or, in other words, the probability of suffering from the disease. If you have a high risk does not mean that you will definitely develop the disease, but that your chances are higher and therefore you should go to your doctor so that with this information schedule the frequency of your reviews, medications, etc. In the same way, a low risk does not totally rule out the appearance of the disease, although the probabilities are lower.

Genetic risk

In recent years, studies have been conducted that have identified certain genetic patterns that are frequently repeated in people affected by a disease. In this way, it has been possible to relate the presence of variations (polymorphisms) in certain genes with the highest probability of suffering from a disease.

Limitations of genetic testing

The genetic test is based on the study of polymorphisms that consist of the change of a single nucleotide (SNP) in a specific area of the genome. It must be borne in mind that there may be rare or infrequent polymorphisms associated with the risk of suffering diseases that have not yet been discovered or that are so rare that their effects can not be determined in epidemiological studies. That is to say, it may happen that the patient has some of these variations in other genes that affect their risk of the disease but that nowadays can not be analyzed as previously mentioned.

Therefore, although this genetic test is based on the latest scientific research, it may be that in the future new genetic variations are discovered that improve the prediction of the risk of suffering from a certain disease.

However, the state of current science, already allows to draw interesting conclusions from the clinical point of view, which help physicians to improve their decisions.


Expand the information on this topic


Abbreviation of deoxyribonucleic acid, which is the molecule that contains all the genetic information of a person


Each of the alternative forms that a gene can have that differ in their sequence.


Each of the structures that result from the packaging of DNA during cell division.


Sequence (fragment) of DNA that constitutes the unit for the transmission of hereditary characters.


Set of the genes of an individual contained in the chromosomes.


Combination of the variants of a gene in an individual.


When the two alleles of the same gene are different.


When the two alleles of the same gene are the same.


Each of the units that make up the DNA.


Variation in the nucleotide sequence of genes between individuals.

Adenomatous polyps

Abnormal growth of potentially cancerous mucosal tissue


Ordered succession of the units (nucleotides) that constitute a gene.


English abbreviation of the technique of polymerase chain reaction (Polymerase Chain Reaction) by which millions of times are amplified minimum amounts of DNA, which allows to detect precise and specific genetic sequences.

The FEHV clinic is a pioneer in the use of genetic diagnostic tests, offering the novel PNPLA3 gene test.


  • GRIFFITHS, A.J.F., S. R. WESSLER, R.C. LEWONTIN & S. B. CARROLL (2008). Genética. MGraw-Hill Interamericana. Novena edición.
  • KLUG, W.S. & CUMMINGS, M.R. (1998). Conceptos de Genética. 5.ª Edición. Prentice Hall. España.
  • BENITO-JIMÉNEZ, C. (1997). 360 Problemas de Genética. Resueltos paso a paso. 1.ª Edición. Editorial Síntesis. España.
  • MENSUA, J.L. (2002). Genética: Problemas y ejercicios resueltos. Prentice.

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Dr. Vicente Carreño
Hepatology specialist


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