WS11.1 Highlighting the importance of carrier testing in CF families

Objective Carrier testing enables relatives of CF patients to know their status regarding the CFTR mutation that segregates within their family. This test enables prevention in families and thus detection of new 1/4 risk couples. Our study aimed to assess the impact of carrier testing and to search for the predictors of uptake to this test in an area where CF is frequent. Methods Forty patients born in the district of Finistere (Brittany, France) between 1980 and 2004 were enrolled in the study. Family trees were faced with the carrier tests performed in the genetic laboratories of the area. Results Among the 459 non-parent relatives eligible for testing, 185 made the test, leading to an adjusted percentage of uptake of 40.7% (95% CI: [34.1%; 47.3%]). Carrier testing enables detection of 5 new 1/4 risk couples, leading to 8 prenatal diagnoses and 5 terminations. This test also allows to reassure many relatives (as non carrier by testing or deduction, n=247), plus 60 couples (in whom the mate of a carrier relative was negative). Finally, logistic regression adjusted for clustering revealed that the main predictors of being tested were female gender (OR = 1.6, p=0.006), having a high a priori risk (OR 1/2 vs 1/4 = 3.7, p=0.004; OR 2/3 vs 1/4 = 31.8, p Conclusion Our study assesses, for the first time in Europe, uptake of CF carrier testing, a critical tool to reassure non carriers and to detect new at-risk couples. It also highlights factors influencing the choice to be tested. Study funded by Vaincre La Mucoviscidose.