Kaskadno genetsko testiranje v družinah s sindromom Lynch Cascade genetic testing in Lynch syndrome families

Povzetek

Izhodišče: Sindrom Lynch (LS) je najpogostejša oblika podedovane genetske predispozicije za raka debelega črevesa in danke (RDČD). Prisotnost LS je posledica zarodne patogene različice/verjetno patogene različice (PR/VPR) v enem od genov popravljanja neujemanja baznih parov (MMR). Ker je LS povezan s povečano ogroženostjo za raka, je pomembno testirati tako posvetovance kot njihove družinske člane (kaskadno testiranje). Metode: Na Oddelku za onkološko klinično genetiko Onkološkega inštituta Ljubljana (OIL) smo opravili analizo podatkov, ki smo jih pridobili iz podatkovne zbirke oddelka. Analizirali smo podatke napotenih na genetsko svetovanje v obdobju od 1. 1. 2007 do 31. 12. 2023, pri katerih je obstajal sum na prisotnost LS. Pri tem smo uporabili deskriptivne statistične metode. Rezultati: Na genetsko svetovanje je bilo zaradi ugotovljene različice v enem od genov, ki jih povezujemo z LS, v 17-letnem obdobju, napotenih 246 posameznikov iz 97 pozitivnih LS družin. Od tega je bilo pozitivnih 170 posameznikov, kar predstavlja 69,1 % vseh testiranih. Kaskadnega testiranja se je udeležilo 157 družinskih članov iz 54 družin (55,7 % glede na vse pozitivne družine), in sicer 100 žensk (63,7 %) in 57 moških (36,3 %). 90 posameznikov (57,3 %) se je odzvalo v roku 12 mesecev od razkritja rezultata prvemu testiranemu. Povprečno število krvnih sorodnikov na družino, ki so se odločili za predsimptomatsko testiranje, je bilo 1,6. Če odštejemo družine, v katerih se ni javil nihče od svojcev, pa znaša to število povprečno 2,9 svojca na družino. Zaključek: Kaskadno genetsko testiranje je uspešen sistematični proces zagotavljanja genetskega testiranja krvnih sorodnikov nosilcev PR/VPR. V primeru LS se je pri 55,7 % pozitivnih družin za kaskadno testiranje odločil vsaj en krvni sorodnik. V družinah, v katerih so sorodniki prišli na kaskadno genetsko testiranje, so v povprečju prišli skoraj trije – skoraj 60 % v enem letu.

Abstract (Eng)

Introduction: Lynch syndrome (LS) is the most common form of inherited genetic predisposition to colorectal cancer (CRC). LS is caused by a germline pathogenic/likely pathogenic variant (P/ LPV) in one of the mismatch repairs (MMR). Since LS is linked to an increased risk of cancer, it is crucial to test both individuals and their family members (cascade testing). Methods: We performed the analysis of data from the Department of Clinical Cancer Genetics, the Institute of Oncology Ljubljana, i.e. the information on individuals suspected of LS who were referred for genetic counselling between 01/01/2007 and 31/12/2023. The research was conducted using descriptive statistical methods. Results: A total of 246 individuals from 97 LS-positive families were referred for genetic counselling in 17 years. 170 individuals tested positive, representing 69.1% of all individuals tested. 157 family members from 54 families (55.7%) participated in cascade testing. There were 100 women (63.7%) and 57 men (36.3%). In families where the relatives opted for cascade testing, 90 individuals (57.3%) responded within 12 months after the positive result had been disclosed to the first individual tested. On average, 1.6 blood relatives per family participated in presymptomatic testing. In 54 families where relatives opted for testing, the average number of those who decided to test was 2.9 relatives per family. Conclusion: Cascade genetic testing is a successful systematic method for providing genetic testing to blood relatives of P/LPV carriers. In the case of LS, 55.7% of positive families had at least one blood relative opting for cascade testing. In families where relatives underwent cascade testing, an average of nearly three relatives participated, with almost 60% responding within 12 months.