Affected are represented as diamonds, carriers as squares, and unaffected as triangles. (a) IBMFRS Score v. Age. IBMFRS declines in affected individuals with older individuals in this cohort, while unaffected stays constant. The trendline for unaffected individuals is solid (y = 0.0009x + 39.838, p-value = 0.92). The trendline for carriers is dotted (y = −0.1735x + 45.264, p-value = 0.31). The trendline for affected individuals is dashed (y = −0.5363x + 55.096, p-value = 0.01). (b) 6MWT v. Age. Decline in all groups at older age, regardless of condition. The trendline for unaffected individuals is solid (y = −4.0252x + 744.03, p-value = 0.02). The trendline for carriers is dotted (y = −7.828x + 796.11, p-value = 0.12). The trendline for affected individuals is dashed (y = −7.4643x + 758.23, p-value = 0.08). (c) Manual Muscle Test Total MRC Score v. Age. MRC score declines for older affected individuals, while unaffected stays constant. The trendline for unaffected individuals is solid (y = −0.0591x + 282.6, p-value = 0.40). The trendline for carriers is dotted (y = 0.0155x + 266.35, p-value = 0.99). The trendline for affected individuals is dashed (y = −3.4974x + 385.03, p-value = 0.01).