A 12 yr old child presented to me with history of ataxic gait since 3 years and unable to stand since last one year.He has severe muscle atrophy of both upper and lower limb with absent deep tendon reflexes and plantar response flexor bilaterally.No signifant family history.foot has pes cavus.on ECG findings s/o RBBB present with normal ecocardiography.MRI spine shows cord atrophy .Muscle biopsy report awaited.ophthalmological exam wnl,no telengectasia.cbc wnl How to proceed further for diagnosis? Could it be fredrich ataxia?