To evaluate the resolution of uncertain results in a limb-girdle muscular dystrophy type 2 (LGMD2) cohort.

Positive genetic testing for LGMD2, a group of autosomal recessive conditions, can guide clinical management. For patients receiving uncertain results, direct evidence (e.g. clinical information, genotyping relatives’ samples) can be requested, which may accelerate reclassification. Sarepta Therapeutics and Invitae^® partnered to monitor reclassification and outreach to clinicians of patients with LGMD2 uncertain results.

Eligibility criteria included either 1) one pathogenic/likely pathogenic (P/LP) variant plus one variant of uncertain significance (VUS) or 2) two VUS in one of six LGMD2 genes (ANO5, CAPN3, DYSF, SGCA, SGCB, SGCG). Results at report release and at a fixed timepoint (August 2023) were compared. Direct evidence upgrades for outreach and non-outreach cohorts were calculated, and reclassification proportions evaluated.

Of 33,429 tested patients, 4,324 (13%) had positive results; 284 (<1%) had eligible uncertain results. Outreach was performed for eligible clinicians (57% open rate). 123 outreach cases were analyzed (exclusion included opt-out and study ineligibility). Provision of additional clinical information and genotyping of relatives occurred in both the outreach and non-outreach groups per standard Invitae VUS resolution guidance. Results were reclassified in 39/123 (32%) of the outreach group and 58/161 (36%) of the non-outreach group. Results were upgraded in 23/39 (59%) of the outreach group and 36/58 (62%) of the non-outreach group. Direct evidence contributed to 14/23 (60%) and 20/36 (56%) upgrades in the outreach and non-outreach cohorts, respectively.

Reclassification efforts for LGMD2 patients are aided by collection of information and relatives’ samples post-initial results. Standard VUS resolution messaging was sufficient in this cohort to trigger provision of additional information/samples. Further studies should focus on predicting patients/clinicians who will not participate after standard VUS resolution messaging for more focused outreach efforts.