N-glycation of alpha-1 acid glycoprotein as a potential diagnostic marker for monogenic type of diabetes mellitus HNF1A-MODY

Diabetes mellitus je teška kronična bolest koju uzrokuje nemogućnost gušterače da sintetizira inzulin ili nemogućnost organizma da funkcionalno koristi sintetizirani inzulin (WHO, 1999.). Diabetes mellitus se, obzirom na mehanizam razvoja bolesti, može podijeliti na više podtipova, a najčešće pogrešno dijagnosticiran tip dijabetesa je MODY (Maturity-onset Diabetes of the Young). MODY dijabetes je heterogena skupina poremećaja uzrokovanih mutacijama u različitim genima, a najčešći tip je MODY3 uzrokovan mutacijom gena HNF1A za istoimeni transkrpicijski faktor. Mutirani transkripcijski faktor HNF1A dovodi do abnormalne regulacije sinteze inzulina u β-stanicama Langerhansovih otočića pankreasa zbog čega dolazi do razvoja šećerne bolesti. Dosadašnjim istraživanjima ustanovljeno je da do najboljeg terapijskog ishoda kod MODY pacijenata dovodi liječenje sulfonilurejama, no, zbog često pogrešno postavljene inicijalne dijagnoze, pacijentima se daje metformin koji ne dovodi do poboljšanja stanja i povlačenja simptoma. Mutacije gena HNF1A su heterogene; neke od njih su benigne, više različitih dovodi do razvoja bolesti, a nekima još uvijek nije dodijeljeno značenje. Stoga su metode molekularne dijagnostike u dijagnostici MODY dijabetesa manjkave i često pružaju rezultate kojima se, zbog manjka literaturnih podataka, ne može dodijeliti kliničko značenje. Prepoznato je kako mutacije u transkripcijskom faktoru HNF1A dovode do promjene glikozilacije α-1 kiselog glikoproteina, te se može pretpostaviti kako bi iscrpna analiza strukture i sastava glikana na α-1 kiselom glikoproteinu dala adekvatnu informaciju o funkcionalnosti transkripcijskog faktora HNF1A, pa tako i o kliničkoj slici pacijenta. U ovom istraživačkom radu glikopeptidi su analizirani masenom spektrometrijom spregnutom na tekućinsku kromatografiju kojom je moguće usporediti velik broj uzoraka obzirom da metoda trpi istovremeno analiziranje velikih kohorti. Glikopeptidi su ispitani u 90 uzoraka plazme pri čemu je njih 72 pripadalo osobama bez mutacije u HNF1A genu, a njih 18 pojedincima s potvrđenom oštećujućom mutacijom HNF1A. Statističkom obradom podataka pomoću Mann Whitney testa ustanovljeno je kako je prisutna statistički značajna razlika u fukozilaciji AGP-a između ispitanih skupina.Diabetes mellitus is a severe chronic disease caused by the inability of the pancreas to synthesize insulin or the inability of the body to functionally use synthesized insulin (WHO, 1999). Diabetes mellitus, according to the mechanism of disease development, can be divided into several subtypes, and the most commonly misdiagnosed type of diabetes is MODY (Maturity-onset Diabetes of the Young). MODY diabetes is a heterogeneous group of disorders caused by mutations in different genes, and the most common type is MODY3 caused by a mutation in the HNF1A gene for the transcription factor of the same name. Mutated transcription factor HNF1A leads to abnormal regulation of insulin synthesis in the β-cells of the pancreatic islets of Langerhans leading to the development of diabetes. Previous research has shown that treatment with sulfonylureas leads to the best therapeutic outcome in MODY patients, but due to the often misdiagnosed initial diagnosis, patients are given metformin which does not lead to improvement and withdrawal of symptoms. Mutations in the HNF1A gene are heterogeneous; some of them are benign, more different leads to the development of the disease, and some have not yet been assigned meaning. Therefore, molecular diagnostic methods in the diagnosis of MODY diabetes are deficient and often provide results that, due to lack of literature data, cannot be assigned clinical significance. It has been recognized that mutations in the transcription factor HNF1A lead to changes in the glycosylation of α-1 acid glycoprotein, and it can be assumed that a comprehensive analysis of the structure and composition of glycans on α-1 acid glycoprotein would provide adequate information on the functionality of transcription factor in HNF1A. patient. In this research work, glycopeptides were analyzed by mass spectrometry coupled to liquid chromatography by which it is possible to compare a large number of samples since the method can simultaneously analyse large cohorts. Glycopeptides were tested in 90 plasma samples, of which 72 belonged to individuals without a mutation in the HNF1A gene, and 18 to individuals with a confirmed damaging HNF1A mutation. Statistical processing of the data using the Mann Whitney test revealed that there was a statistically significant difference in AGP fucosylation between the examined groups