Medical Genetics - V. M. Zaporozhan 2005

Multifactorial Diseases
Pharmacogenetics
Examples of pharmacogenetic reactions – Malignant hyperthermia

It is associated with a mutation in the sarcoplasmic ryanodine receptor Gene (RYR1). The administration of inhalation anesthetics (halothane, ethyl ether, methoxyflurane) and certain Muscle relaxants triggers an uncontrolled release of calcium from the sarcoplasm, leading to metabolic acidosis. Affected patients experience a rapid rise in body Temperature up to 42 °C or higher, accompanied by tachycardia, tachypnea, and Hypoxia, with cardiac arrest potentially resulting in death.

Examples of other pharmacogenetic traits are given in Table 7.12. An extensive and continually updated list of genetic polymorphisms related to drug efficacy and adverse effects can be found online at www.sciencemag.org/feature/data.

Table 7.12. Examples of genetic polymorphism associated with altered drug response

Protein

Drugs

Outcome

G6PD variants

Sulfonamides, furazolidone, nitrofurans, quinidine, primaquine

Hemolysis

Hydroxylation Enzymes (poor metabolizers)

Debrisoquine

Sparteine

ß-blockers (propranolol, metoprolol)

Hypotension

Heart Failure, bradycardia, lowered Blood pressure

Calcium channel receptors

Inhalation anesthesia with halothane

Malignant hyperthermia up to 42 °C

Pseudocholinesterase variants

Dystilin, suxamethonium

Prolonged apnea

Catechol-O-methyltransferase polymorphism

L-DOPA

Inefficacy

Thiopurine methyltransferase polymorphism

Mercaptopurine

Inefficacy

Peroxisome proliferator-activated receptor

Insulin

Variations in insulin sensitivity

Dopamine receptor DD3R

Neuroleptics

Development of tardive dyskinesia in schizophrenic patients


Last update: 11/08/2026

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