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The index patient, a 20-year-old man, presented with abnormal gait, toe-walking, hip swinging, and a wide-based gait from early childhood. Over time, he developed proximal muscle weakness, hand stiffness, and leg pain. Genetic testing confirmed a pathogenic MYOT c.170C>T variant. At age 13, he developed progressive bilateral non-fatigable ptosis, prompting tests for acetylcholine receptor binding and muscle-specific kinase antibody, both negative. An ophthalmology examination ruled out other causes of eyelid ptosis. Serum creatine kinase was mildly elevated at presentation. His cardiac and pulmonary functions are preserved. 

The patient's paternal half-sister reported leg pain and left ptosis at age 13, with ankle flexion contractures mild left ptosis, and absent facial or limb muscle weakness on examination. 

The patient’s biological father, diagnosed with presumed limb-girdle muscular dystrophy at 25, lost ambulation in his thirties and exhibited ptosis. His wife noted severe ptosis made him appear asleep while watching TV, despite being awake. He died at age 50 due to respiratory failure. Other family members, including the paternal grandmother, uncle, and two aunts, presented with myopathy but without ptosis.