Human Genome: Understanding DNA, GMOs, and Genetic Diseases

Posted on Dec 8, 2024 in Biology

Universal Statement on the Human Genome and Human Rights

The human genome is the basis of the fundamental unity of all members of the human family and the recognition of their inherent dignity and diversity. In a symbolic sense, the genome is the heritage of humanity.

  • Each individual is entitled to respect for their dignity and rights, regardless of their characteristics.
  • That dignity makes it imperative not to reduce individuals to their genetic characteristics and to respect the uniqueness of each and their diversity.
  • The human genome in its natural state shall not give rise to financial gain.

An investigation, treatment, or diagnosis related to the genome of an individual can only be made after a rigorous assessment of the risks and benefits pertaining thereto and in accordance with any other requirement of national legislation.

No one shall be subjected to discrimination based on their genetic characteristics.

The Greatest Biological Discovery of the 20th Century

The greatest biological discovery of the twentieth century is the DNA double helix, consisting of two chains joined in the shape of a spring. Each chain forms one of the two ribbons, and one string is attached to the other through the nucleotides.

The Key is in the Base

DNA molecules are very long but are formed by the repetition of just four basic subunits, called nucleotides (Adenine, Thymine, Cytosine, Guanine). These are grouped in pairs A+T and G+C. The chains are complementary; each strand serves as a template to produce a new string coupling the corresponding nucleotides. The order of the genetic basis is called the sequence and is what distinguishes one individual from another.

Genetically Modified Foods

Genetically modified (GM) foods are derived from, or with the participation of, GMOs (genetically modified organisms).

Food Labeling

Genetically modified foods must be identified as stated in the new regulations published by the European Union in April 2004. They will be labeled if:

  • GM-food (maize)
  • A product containing GMOs (corn salad)
  • A food produced from genetically modified organisms (corn oil)

There are exceptions:

  • Foods containing only 0.9% of GM, because they are considered to be introduced “accidentally” in the food chain.
  • Products of the second or third generation (food of animal origin from animals fed with GM food).
  • Food employing transgenic microorganisms for fermentation (no need to indicate if the GMO is not present in the final product, but if the organism is in the food, it will have to be specified).

Applications and Risks of GMOs

Biotechnology is the use of living organisms or their products for commercial and/or industrial purposes. Its application covers different areas:

  • Food industry: food production with special characteristics (grain gluten-free).
  • Pharmaceutical industry: production of pharmaceuticals or vaccines (for animals whose milk contains a blood clotting factor).
  • Agriculture and livestock: improved agronomic characteristics (resistance to pests or herbicides from plants).
  • Environment: toxic waste disposal plants capable of resisting the presence of toxic substances that accumulate in your body.
  • Medical research: procurement of organs for transplantation from transgenic animals that pose no problem of rejection.

Risks of Biotechnology

Despite its obvious advantages, biotechnology also has risks, for example:

  • The loss of genetic diversity, crop diversity loss.
  • The “jump” of accidentally transferred genes to other wild species or traditional crops could create herbicide-resistant weeds or pathogenic bacteria that incorporate the antibiotic resistance genes used as markers.
  • Adverse effects on health.

Transposons -> fragments of DNA that can jump from plant to plant.

Human Genome Project

The project was conceived in two parts: identify the existing genes and determine the exact sequence of nucleotides. Sequence of the human genome:

  • Public Art Consortium: chromosomes are divided into regions for maps with a scale of increasing accuracy.
  • They divide and study one, bringing together all human chromosomes (23 pairs) to analyze.
  • Sequencing is the last step.
  • The Technique of Celera (Shotgun): detected by computer programs where they overlap and meet the pieces.
  • Fragments into millions of fragments, randomized, with 23 pairs of human chromosomes.
  • Each fragment is sequenced to order it, then the genetic map.

Can You Patent Genes?

The European Patent Convention prohibits the patenting of human genes, even when the function is known. The invention is patentable if, that is, the particular drug or treatment for which that gene is to be used.

Completion of the Human Genome Project

On April 14, 2003, the Human Genome Project (HGP) announced the complete sequencing of the human genome.

Characteristics of the Human Genome

  • The human genome contains about 3.2 billion base pairs.
  • Only 2% of the genome contains genes, i.e., information to make proteins.
  • A very high percentage consists of the so-called junk DNA, whose function is not exactly known.
  • It’s almost the same for all individuals; only 0.1% difference between people.
  • It contains about 25,000 genes, a number similar to that of a chimpanzee or a mouse, and the function is unknown for half of them.

Biotechnology and Genetic Diseases

The possibility of replacing the gene for a disease with the normal gene is called gene therapy.

What is a Genetic Disease?

It is when a normal chromosome suffers a change, i.e., mutated or not doing its usual role. So the change affects all body cells, producing the genetic disease, which is hereditary. They can be:

  • Chromosomal: are the result of problems that affect entire chromosomes or chromosome fragments.
  • Monogenic: are due to changes in a single gene and inherited like any other character. Cystic fibrosis is caused by a recessive mutant allele on chromosome 7, an autosome.

Prenatal Diagnosis

For certain genetic diseases, an early diagnosis can be made in utero. This diagnostic modality is called prenatal diagnosis. Amniocentesis and chorionic villus sampling are prenatal diagnostic methods to detect DNA and chromosomal abnormalities and biochemical studies.

Both techniques have the disadvantage of slightly increasing (1%) the rate of spontaneous abortions. With IVF techniques (in vitro fertilization), it is possible to make a preimplantation diagnosis. The tests are done from one of the cells of the morula, and the embryo is kept frozen.

Amniocentesis

Amniocentesis is a sample of amniotic fluid containing fetal cells in suspension using a hypodermic needle. The cells are separated from the fluid by centrifugation. The cells are grown in a laboratory.

Sampling of the Chorionic Villi

Sampling of the chorionic villi involves taking a small sample of tissue from the developing placenta, using a catheter inserted through the vagina with the help of an ultrasound. Chromosome studies are performed later, biochemical or DNA. The results take between one to three weeks.

Gene Therapy

Current medicine is preparing for a change as revolutionary as was once the discovery of antibiotics or vaccines. Gene therapy is the use of genes to cure or alleviate diseases, both inherited and acquired.

  1. Cells are taken from the patient.
  2. A virus (vector) is modified in the laboratory so as to be unplayable.
  3. A gene is inserted into the virus.
  4. The patient’s cells are contacted with the modified virus.
  5. Genetic modification of the patient’s cells occurs.
  6. The modified cells are injected into the patient and start producing the desired proteins.

Ethical Dilemmas

In any case, the use of this knowledge is associated with certain aspects that cannot be overemphasized, such as the following:

  • Confidentiality: medical confidentiality also applies to the information generated by genetic diagnosis.
  • Autonomy: the decision to know or not know should be free and voluntary. Tests may exist for many genetic diseases for which there are no effective treatments to cure or reduce their consequences.
  • Information: Autonomy and information are the basis for informed consent, a prerequisite in clinical bioethics.
  • Justice: refers to equal opportunity without discrimination of a social, economic, racial, or religious group.
  • Profit: any decision should always be made thinking about the benefit of the individual concerned, if possible avoiding diagnostic errors, and not creating false expectations.