Table 1. Clinical data of the patients.

Case Age Sex	Symptom onset (age in years)	Course	Current status: (age) functional ability	Current status Muscle weakness	Current status Muscle atrophy	CPK/ EMG / Cardiac echography/ EKG/ Vital capacity
Case I Proband (III:3) 61y	Right hand atrophy / weakness (finger extensors) (≈ 30y)	Progressive worsening Around 30y: both hands wasting, inability to stand on heels and tiptoes, 35 y difficulties climbing stairs. 46 y Gowers, difficulties standing from a chair, running inability. Increased weakness of foot evertors, hand finger extensors 52y: cervical myelitis manifesting by left foot extending to whole limb after 6 months. sensory defect without identified cause (Spine MRI T2 sequence hypersignal from C2 to C7) (normal Brain MRI, normal CSF fluid) Increased loss of balance and cordonnal pains 53 y: fallings (weakness and balance impairment) 59 y: walk with bilateral aid	(61y) Walking distance: few hundreds meters with aid Fallings, four to five times monthly right foot elevator Difficult walk with steppage and tendency to internal rotation of feet 10 m in 15 s with a cane. Inability to stand on heels and tiptoes Rising from chair 9 times in 60 s with two hands Thigh crossing: difficult Arm elevation: normal Painful spinal posterior column syndrome (myelitis)	Lower limbs Toes extensors 2, except big toe, 1, Peroneus lateralis 1, Tibialis anterior 4, Post legs 2+ Hamstrings 2, Quadriceps 5- Adductors 2+, Glutei medii 4+, Iliopsoas 3 + Upper limbs Finger extensors 3-, index more affected: right index 2, left 2+ Finger flexors 4+ wrist extensors 4 scapular and brachial 5 Axial,facial, oculobulbar normal in addition: hypoesthesia of whole left lower limb due to myelitis	Legs (both compartments) Hand: palmar, mosly thenar region	CK normal EMG: myogenic Distal in Lower limbs, Distal + proximal in lower limbs Nerve: normal No decrement Normal echography and EKG VC: 85%
Case II Son of case I (IV:2) 33 y	Difficulties standing on tiptoes and heels fatigability in walking (14y)	Mild progression At 16 y, interruption of sport at school and inability to run.	(33y) Walking distance: 1000 m without aid No fallings Climbing stairs with banister 10 m: 12s Rising from a chair: 24 times in 60 s without aid Arm elevation: normal	Lower limbs Peroneus 3-, Tibialis anterior 3+ Toes extensors between 4, and 2 (big toe) Post legs 2 Pelvic and femoral muscles 5 Upper limbs Finger extensors 4+, Finger flexors 5 wrist extensors 5 scapular and brachial 5 Axial, facial, oculobulbar normal	Legs, mainly posterior compartment No atrophy of upper limbs	CK normal EMG: diffuse myogenic pattern Nerve: normal Normal echography and EKG VC: 86%

Abbreviations: CSF (Cerebral spinal fluid); EKG (Electrocardiogram); EMG (Electromyogram); VC (Vital capacity); CK (Creatine Kinase)