• Nutrigenetics

Nutrigenetics studies the relationship between genetic heritage and food metabolism

Identification of genetic variants underlying individual response to specific nutrients

Nutrigenetics studies the relationship between genetic heritage and food metabolism, through the identification of genetic variants underlying individual response to specific nutrients. Molecular biology technologies have allowed to unveil a direct correlation between food and genes: people responds very differently to the same foods as human population presents high number of gene variants (polymorphisms). These can significantly modify gene expression or the functional efficiency of the relative protein. Gene polymorphisms (and the related consequences at the molecular level) can influence the way a nutrient is metabolized. They do not represent and determine a disease on its own; however, if the gene polymorphism is associated with an incorrect introduction of particular nutrients (DNA/environment interaction), it may result in a different predisposition towards specific pathological conditions. Large-scale analysis has shown that particular gene variants are associated with predisposition to diseases such as diabetes, cardiovascular disease, osteoporosis and even some forms of cancer. Some of these variants can also lead to increased susceptibility to certain food tolerances (e.g. lactose, gluten etc.).

Genechron offers the analysis of the following polymorphisms:

C3175G and T3206G

The C-13910T and G-22018A polymorphisms of the lactase-encoding gene (LCT) have been linked to adult hypolactasia, which is a decrease in lactase activity leading to lactose intolerance.

The genetic test for the determination of predisposing haplotypes (HLA-DQ2 and DQ8) allows to identify the presence of unfavorable variants that reveal a genetic predisposition and allows to foresee a diagnostic and / or therapeutic procedure with a specialist doctor

Fructose intolerance (Hereditary Fructose Intolerance, HFI) is a disease that prevents eating foods containing fructose, particularly fruits and vegetables. HFI is caused by the presence of mutations in the ALDOB gene that encodes an enzyme, fructose-1-phosphate aldolase, which allows fructose to be used for energy purposes in the hepatic cell.

The rate of metabolism of caffeine by our body depends on the presence of two variants of the CYP1A2 gene, which encodes the enzyme Cytochrome p450 1A2 and allows the metabolism of caffeine: the allelic variant CYP1A2 * 1A encodes the enzyme that metabolizes the slow caffeine, while the CYP1A2 * 1F allele encodes the one involved in rapid metabolism.

The SUOX gene encodes an enzyme involved in the detoxification of sulphites and catalyzes the conversion of sulfite into sulfate, a final step in the oxidative degradation of Cysteine and Methionine. The polymorphisms of the SUOX gene inactivate its detoxification activity with consequent accumulation of sulfites.
The CBS gene, on the other hand, encodes an enzyme necessary to convert Homocysteine into a Cistation with production of ammonia and sulphites. The polymorphisms in this gene lead to an increase in the CBS enzymatic activity with a consequent increase in the levels of sulfites.

The FLG gene encodes a protein, filaggrin, which is the main component of the keratoialin granules of the human epidermis and is essential for the formation and hydration of the stratum corneum. Mutations in the FLG gene, in particular the deletion 2282 of the 4, cause a partial or total loss of the expression of filaggrin causing large changes in the skin barrier, including an increase in dry skin (cutaneous xerosis) and a reduced formation of the stratum corneum (ichthyosis) , as well as an important increase in the sensitivity of the skin to allergens and in particular to nickel.
The TNFa gene encodes the tumor necrosis factor α, a cytokine involved in systemic inflammation and belonging to a group of cytokines that stimulate the reaction of the acute phase. The presence of the A allele in the TNFa -308G / A polymorphism causes an overproduction of the tumor necrosis factor, the activation of inflammatory processes at the systemic level and the predisposition to nickel intolerance.

The ALDH2 gene encodes the mitochondrial acetaldehyde dehydrogenase enzyme involved in hepatocytes in the oxidation of acetaldehyde to acetate. The E504K polymorphism limits the enzymatic activity and causes acetaldehyde accumulation following the intake of alcohol that causes nausea and vomiting. Low activity of ALDH2 is associated with intolerance towards alcoholic beverages and protects against alcoholism.
The ADH2 gene encodes alcohol dehydrogenase 2, an enzyme that catalyzes the conversion of ethanol to acetaldehyde. The H48R polymorphism involves the reduction of the activity of ADH2, the alcohol taken is particularly pleasant, favoring its intake.
The ADH1C gene codes for alcohol dehydrogenase type 1C, the main liver enzyme responsible for the metabolism of ethyl alcohol. The presence of I350V polymorphism in the ADH1C gene determines low enzymatic activity with consequent reduction in the ability to metabolize ethanol.

C-28T and T175C

The C677T and A1298C polymorphisms of the MTHFR gene cause a reduction in the enzymatic activity of the resulting gene in an altered homocysteine level. Hyperhomocysteinemia is related to a greater tendency to thrombotic events, hypertension (due to arteriolar constriction), renal dysfunction, increased sodium reabsorption and oxidative stress.
The MTR gene encodes an enzyme that is involved in the conversion of homocysteine in methionine. The A2756G polymorphism decreases the activity of this enzyme, affecting the blood levels of folate and homocysteine.
The MTRR gene encodes the enzyme Methionine synthase reductase, necessary for the formation of a derivative of vitamin B12. This enzyme is essential to maintain an adequate amount of cellular vitamin B12, methionine and folate, and to maintain low homocysteine levels.
The TCN2 gene encodes transcobalamin 2, a globulin that acts as a transporter for vitamin B12. A polymorphism has been identified in the TCN2 gene (C776G) which causes a related alteration with a possible increase in homocysteinemia and reduction of Vitamin B12.

The Gly16Arg and Gln27Glu polymorphisms in the ADRB2 gene, which encodes the β2-adrenergic receptor, are related to clinical and pharmacological implications in cases of asthma, hypertension, ischemic heart failure, diabetes, obesity and cystic fibrosis.
The Trp64Arg polymorphism in the ADRB3 gene, which encodes the β3-adrenergic receptor, is associated with some cardiovascular risk factors, such as obesity, insulin resistance, early onset of non-insulin-dependent diabetes mellitus and high blood pressure .
The APOA2 gene encodes the apolipoprotein A2, which binds lipids to create molecular aggregates for the transport of cholesterol and triglycerides through circulation to tissues and organs.
The -265 C-T polymorphism in the APOA2 gene in heterozygosity or in homozygous CC could be associated with an increased risk of obesity or of metabolic syndrome development.
The FABP2 gene encodes the intestinal fatty acid binding protein 2. The A54T polymorphism in the gene appears to influence fat absorption. The carriers of the heterozygous or homozygous variant tend to have a greater body mass index than wild-type individuals, have an increased risk of cardiovascular disease and a greater sensitivity to refined carbohydrates.
The Leu7Pro polymorphism in the NPY gene encoding the neuropeptide Y is associated with higher concentrations of total cholesterol, LDL cholesterol and serum triglycerides.

C677T and A1298C

The ACE gene, which encodes the angiotensin-converting enzyme, is characterized by a polymorphism that can cause an insertion (I) or a deletion (D) of an alu sequence of 289bp in intron 16. Both the homozygous genotype DD that the heterozygous ID are associated with an increased risk of coronary and renal disease, hypertension, atherosclerosis and greater sensitivity to salt.
The ACTN3 gene encodes the alpha-actinin-3 protein, responsible for rapid muscle contraction. The R577X polymorphism may be an advantage for endurance sports in those carriers of the mutated allele, while the wild-type (R) variant for sprinting and for strength sports.
The CYP1A2 gene encodes the cytochrome p450 1A2 enzyme which allows the metabolism of caffeine. The polymorphism analyzed in the genetic test influences the rate of caffeine metabolism: the allelic variant CYP1A2 * 1A encodes the enzyme that metabolises caffeine in a slow way, while the CYP1A2 * 1F allele that has a rapid metabolization. Individuals who slowly metabolize caffeine must limit their daily intake: excessive caffeine consumption may result in an increased risk of cardiovascular disease and particularly heart attack.

The TaqI, BsmI and FokI polymorphisms in the VDR gene, which encodes the nuclear receptor that mediates the functions of Vitamin D, involve altered gene transcription and is associated with changes in bone mineral density, calcium absorption, and metabolic disorders and in susceptibility to infectious diseases.