Proučevanje vpliva genetskih polimorfizmov v genih IMPDH1 in IMPDH2 na aktivnost inozin-5’-monofosfat dehidrogenaze v slovenski populaciji

Biškup, Nika (author), Šmid, Alenka (mentor), Urbančič, Dunja (comentor)

Encim inozin-5’-monofosfat dehidrogenaza (IMPDH) katalizira pretvorbo inozin-5’-monofosfata v ksantozin-5’-monosfosfat in predstavlja dejavnik, ki omejuje hitrost sinteze gvaninskih nukleotidov de novo, ki so potrebni za neovirano celično rast in proliferacijo. Genetski polimorfizmi v IMPDH1 in IMPDH2 imajo potencialen vpliv na aktivnost IMPDH, zato bi lahko vplivali na farmakološki učinek zdravilnih učinkovin, ki delujejo na ali se presnavljajo z IMPDH. Mednje sodijo mikofenolna kislina in tiopurini. To so imunosupresivne zdravilne učinkovine, ki lahko izzovejo resne neželene učinke, zato je ustrezno odmerjanje zelo pomembno. S prilagoditvijo terapije glede na genetske dejavnike bi lahko dosegli večjo varnost zdravljenja, manj neželenih učinkov in nižje stroške zdravljenja. Z namenom proučevanja povezave med genetskimi polimorfizmi in aktivnostjo IMPDH smo izvedli raziskavo na vzorcu 154 zdravih slovenskih prostovoljcev. Z metodo analize talilne krivulje visoke ločljivosti smo posameznike genotipizirali za polimorfizme rs2278293, rs2288550, rs558132944, rs121912550 in rs11706052 v IMPDH1 in IMPDH2. V vzorcih hemolizatov istih posameznikov smo z metodo HPLC določili aktivnost IMPDH. Najprej smo določili alelne frekvence izbranih polimorfizmov in jih primerjali z alelnimi frekvencami drugih populacij. Frekvenca polimorfizma rs2278293 v slovenski populaciji je primerljiva s frekvencami v svetovni, evropski, ameriški in afriški populaciji. Pogostnost polimorfizma rs2288550 v slovenski populaciji je nad svetovnim, vzhodnoazijskim, ameriškim in afriškim povprečjem, a pod evropskim povprečjem. Frekvenca polimorfizma rs11706052 je primerljiva med vsemi populacijami, z izjemo afriške in vzhodnoazijske populacije. Polimorfizmov rs558132944 in rs121912550 nismo identificirali v vzorcu slovenske populacije. Nadalje smo ugotovili, da se aktivnost IMPDH v vzorcu slovenske populacije porazdeljuje normalno. Razpon vrednosti je znašal 1129–4017 nmol XMP/(g Hb*h), s povprečno vrednostjo 2322 ± 578,4 nmol XMP/(g Hb*h). Ugotovili smo statistično značilno razliko v aktivnosti IMPDH glede na prisotnost polimorfizma rs2288550. Nevariantni homozigoti (CC) in heterozigoti (CG) so imeli višjo aktivnost IMPDH kot variantni homozigoti (GG). Med ostalimi polimorfizmi (rs2278293, rs558132944, rs121912550 in rs11706052) in aktivnostjo IMPDH na slovenski populaciji nismo ugotovili statistično značilne povezave. Ugotovljena povezava med aktivnostjo IMPDH in polimorfizmom rs2288550 bi lahko prispevala k bolj prilagojenemu odmerjanju mofetilmikofenolata in tiopurinov glede na genotip posameznika.

• Language: Slovenian
• Keywords: inozin-5'-monofosfat dehidrogenaza (IMPDH), genetski polimorfizmi, farmakogenomika, alelne frekvence, mofetilmikofenolat
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2024
• PID: 20.500.12556/RUL-165906
• Publication date in RUL: 13.12.2024

Secondary language

• Language: English
• Title: Evaluation of the impact of genetic polymorphisms in IMPDH1 and IMPDH2 genes on the activity of inosine-5'-monophosphate dehydrogenase in the Slovenian population

Abstract

The enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) catalyzes the conversion of inosine-5'-monophosphate to xanthosine-5'-monophosphate and is a rate-limiting factor in the de novo synthesis of guanine nucleotides, which are necessary for unimpeded cell growth and proliferation. Genetic polymorphisms in IMPDH1 and IMPDH2 may affect IMPDH activity and, consequently, the pharmacological effects of drugs that act on or are metabolized by IMPDH, including mycophenolic acid and thiopurines. These are immunosuppressive drugs that can cause serious adverse effects, which implies that the correct dosing is very important. By adjusting therapy to genetic factors, we could achieve greater treatment safety, fewer adverse effects, and lower treatment costs. The aim of this study was to investigate the correlation between genetic polymorphisms and IMPDH activity. We conducted a study on a sample of 154 healthy Slovenian volunteers. Individuals were genotyped for the rs2278293, rs2288550, rs558132944, rs121912550, and rs11706052 polymorphisms in IMPDH1 and IMPDH2 using the high resolution melting analysis. IMPDH activity was determined in hemolysates from the same individuals using the HPLC method. First, we determined the allele frequencies of the selected polymorphisms and compared them with the allele frequencies of other populations. The frequency of the rs2278293 polymorphism in the Slovenian population is comparable to the frequencies in the global, European, American and African populations. The frequency of the rs2288550 polymorphism in the Slovenian population is above the global, East Asian, American and African averages and below the European average. The frequency of the rs11706052 polymorphism is comparable among all populations, with the exception of African and East Asian populations. We did not identify the rs558132944 and rs121912550 polymorphisms in the Slovenian population. Furthermore, we found that IMPDH activity in the Slovenian population is normally distributed. Values ranged from 1129 to 4017 nmol XMP/(g Hb*h), with a mean value of 2322 ± 578,4 nmol XMP/(g Hb*h). We found a statistically significant association between IMPDH activity and the rs2288550 polymorphism. Non-variant homozygotes (CC) and heterozygotes (CG) had higher IMPDH activity compared to variant homozygotes (GG). We did not find statistically significant associations between the other investigated polymorphisms and IMPDH activity in the Slovenian population. The association between IMPDH activity and the rs2288550 polymorphism could contribute to a more precise dosing of mycophenolate mofetil and thiopurines.

• Keywords: inosine-5'-monophosphate dehydrogenase (IMPDH), genetic polymorphisms, pharmacogenomics, allele frequencies, mycophenolate mofetil