What are Polymorphisms (SNPs) and how do they differ from Mutations?

A polymorphism, specifically a Single Nucleotide Polymorphism (SNP), is a genetic variation that occurs in at least 1% of the population. In contrast, mutations are less common genetic changes, with a frequency of less than 1%. While mutations are often associated with diseases, many do not have negative effects and are part of genetic diversity.

Both types of variations can influence the survival and reproduction of organisms. If a genetic change offers an advantage or disadvantage, it may be subject to natural selection (positive or negative). However, some variants simply fluctuate in frequency due to random genetic drift.

How do these genetic changes occur?

1. Errors during DNA replication
   The majority of variations arise from errors in copying DNA that are not corrected. These errors can be caused by:

   • Radiation (UV, X-rays).

   • Environmental chemicals.

2. Genetic recombination
   During meiosis, chromosomes exchange fragments in the process of crossing over, generating unique combinations of genetic variants (haplotypes).

How many genetic variants does an individual have?

The average individual has between 4 and 5 million variants compared to the reference genome, with SNPs making up 99.9% of these variations. Most variants within an individual are common in their population, but some are rare.

When a genetic variant is related to a specific disease or trait, it is called a risk allele, while the alternative allele is considered protective.

Types of SNPs

1. In non-coding regions:
   Between genes or in regulatory sequences. They do not directly affect protein function, but may influence gene expression.

2. In coding regions:

   • Synonymous: Changes in DNA that do not alter the produced amino acid.

   • Non-synonymous: Changes that modify the amino acid sequence, impacting protein function.

   • Nonsense: Create a premature stop codon, truncating the protein.

3. In intronic regions:
   They may affect the RNA splicing process, altering the proteins produced.

Analysis and Techniques to Detect SNPs

SNPs can be analyzed using various genomic techniques, such as:

• Next-generation sequencing (NGS): Identifies variants on a large scale.

• Genetic microarrays: Detect common SNPs in population studies.

• Real-time PCR: Ideal for specific variants.

The results are reported by comparing the analyzed genome with a reference genome, indicating the variants found and their possible implications. To identify/name an SNP, the rsID code is used. This code is the identification of an SNP within a reference genome. The letters "rs" are followed by a numerical code. For example: rs4680.

Application of SNPs in Precision Nutrition

SNPs are the revolution of personalized nutrition. These variations influence:

• Nutrient metabolism: For example, variants in the MTHFR gene affect folic acid metabolism.

• Response to specific diets: Some SNPs are related to sensitivity to fats or carbohydrates.

• Predisposition to metabolic diseases: Such as obesity or type 2 diabetes.

The analysis of an individual's genetic profile allows professionals to design optimized nutritional plans for improving health and preventing diseases.

Knowing the polymorphisms in our DNA not only provides valuable information about the evolutionary past of humanity but also opens doors to much more personalized nutritional care, maximizing the benefits of diet and, in some cases, improving adherence and effectiveness of treatments. DNA tests from N·GENE provide an advanced tool to understand such polymorphisms and therefore genetic predispositions to certain conditions.