We describe extensively the eight patients issued from three French unrelated families with STIM1 mutations, briefly reported in the paper by Bohm et al. (2013). Transmission was autosomal dominant. Onset occurred during childhood (four cases), adolescence (two cases), adulthood (two cases). The first symptom was always related to lower limbs weakness. Examination at age from 21 to 61 years showed: (1) weakness predominating in lower proximal muscles; (2) ophthalmoparesis without ptosis in all members from 2 families; (3) significant contractures in 2 families, affecting elbows, wrists, fingers, heel cords, more severe in one patient with neck and masticatory muscles contractures; (4) sparing of facial and bulbar muscles, no specific cardiac involvement. One patient presented a one week long lower limbs paresis at age 9 years, a second one reported several days long periods of worsening and a moderate daily variability. The course was mildly progressive in seven patients with preserved ambulation at 50 years, no bubar/respiratory involvement. In one patient, evolution was more rapid leading to wheelchair since age of 52 years, respiratory insufficiency, swallowing involvement. Muscle imaging revealed fatty degeneration affecting predominantly thighs and posterior legs. Electromyography showed in all cases myogenic patterns and if tested no decrement. Tubular aggregates were found all biopsied patients. A congenital myasthenic syndrome was initially misdiagnosed in several patients due to ophthalmoplegia and variability of symptoms. In conclusion, a characteristic clinical signature was evidenced in our patients associating proximal lower limb weakness, ophthalmoplegia and contractures. Such a phenotype with tubular aggregates at biopsy prompts to look for STIM1 gene mutations.