P637: Incidence of DMD variants in asymptomatic paternal references in a cohort of patients pursuing PGT-M for DMD-related disorders

Of the 72 patients who received an indeterminate result for CTX on a sterol panel (eg, cholestanol mildly elevated 6.0 mg/L), 19 received a repeat sterol panel, 3 received a CTXP panel, and 2 received both sterols and CTXP on follow-up.Forty-eight patients received no follow-up testing after an indeterminate result.Conclusion: These findings represent six years of CTX testing at a large referral center and highlight the evolving management of this disease.Initial testing and serial monitoring represent a mix of plasma sterol testing, dedicated CTX panels, and/or both.Contributors to this variability may include physician comfort, local expertise, pre-test suspicion of CTX, and patient presentation.While our ability to provide direct comparisons of test performance is limited, heterogeneity in testing suggests that guidelines for diagnosis and monitoring should be revisited, especially as additional biomarkers are identified that could add further complexity and uncertainty.