Work

Predicting Loss of Ambulation in Limb Girdle Muscular Dystrophy R9

Year: 2026

Type: article

Abstract: BACKGROUND: Limb girdle muscular dystrophy type R9 (LGMDR9) results from biallelic variants in FKRP. There is limited data to predict loss of ambulation (LOA) among those with LGMDR9. METHODS: Participants in an ongoing dystroglycanopathy natural history study (NCT00313677) with FKRP variants who had achieved ambulation and were more than 3 years old were included (n = 97). LOA was defined as self-reported full-time wheelchair use, weakness preventing completion of the 10-m walk-run test (10MWT) or 10MWT time > 30 s. Interval-censored time-to-event analysis was used to determine median age at LOA. Receiver operating characteristic curves were used to examine the ability of 10MWT and 4-stair climb (4SC) times to predict LOA. RESULTS: Of 97 participants, 55 (57%) were homozygous for the c.826C>A founder variant. Thirty-one participants lost ambulation; 15 (49%) were homozygous for c.826C>A. Earliest age at LOA was 9 years (non-homozygous for c.826C>A). Median age at LOA for the cohort was 46.0 years. Performances on 10MWT and 4SC were highly predictive of LOA within 3 years, with areas under the ROC curve of 0.89 (10MWT) and 0.87 (4SC) when genotype was included in analysis. Optimal cutoffs for predicting LOA within 3 years differed by genotype and had acceptable sensitivity and specificity. DISCUSSION: LOA among those with LGMDR9 is strongly predicted by performance on 10MWT and 4SC. These results demonstrate the real-world significance of standardized motor function tests used in LGMDR9 clinical trials and aid in anticipatory guidance.

Source: Annals of Clinical and Translational Neurology

DOI: 10.1002/acn3.70299