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Abstract
Objective To accurately categorize the phenotypes of individuals with collagen VI–related dystrophies (COL6-RDs) during the first years of life to predict long-term motor function and pulmonary function, to provide phenotype-specific anticipatory care, and to improve clinical trial readiness.
Methods This retrospective, multicenter, international study analyzed the relationship of long-term motor and pulmonary function with the initial maximal motor ability achieved in individuals with COL6-RD.
Results We studied 119 patients with COL6-RD from Spain (n = 54) and the United States (n = 65). The early maximal motor milestones of ability to rise from the floor unassisted and ability to climb 4 steps without holding onto a railing demonstrated reliability in distinguishing between 3 COL6-RD phenotypic subgroups: (1) Ullrich congenital muscular dystrophy, (2) intermediate COL6-RD, and (3) Bethlem myopathy. Long-term motor function and pulmonary function are strongly correlated with the maximal motor ability achieved during the first years of life. Maximal motor capacity can predict other disease-relevant events such as the age at loss of ambulation and the need for the initiation of nocturnal noninvasive ventilation.
Conclusion This work proposes a prospective phenotypic classification for COL6-RDs that will enable an accurate prediction of a patient's COL6-RD phenotype during the first years of life. The ability to establish a patient's COL6-RD phenotypic classification early will enable a more accurate prognosis of future motor and pulmonary function, thus improving anticipatory clinical care, and it will be instrumental in aiding the design of future clinical trials by allowing early stratification of trial cohorts.
Glossary
- BiPAP=
- bilevel positive airway pressure;
- BM=
- Bethlem myopathy;
- CMD=
- congenital muscular dystrophy;
- COL6=
- collagen VI;
- COL6-RD=
- COL6-related dystrophy;
- FVC=
- forced vital capacity;
- LoA=
- loss of ambulation;
- MFM-32=
- Motor Function Measure-32;
- NIV=
- noninvasive ventilation;
- NSAA=
- North Star Ambulatory Assessment;
- 6MWT=
- 6-minute walk test;
- TH=
- triple helical;
- UCMD=
- Ullrich CMD
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
↵* These authors contributed equally to this work.
- Received August 24, 2020.
- Accepted in final form December 29, 2020.
- © 2021 American Academy of Neurology
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