Dear Sirs,A 27-year-old woman was referred to our center regardingprogressive lower extremity weakness. Her symptomsbegan 3 years ago with fatigue related to the exertion andmild proximal lower extremity weakness. She had nomotor development issues and she denied family history ofneurological disease. There were non ocular or sensorycomplaints. At the age of 20, a routine analysis demon-strated an increase of liver enzymes with a normalabdominal echography. She refused hepatic biopsy andhepatology follow-up visits.The force was reduced to grade 4/5 symmetrically in thehip flexion. The right knee reflex was absent and presentedleft ankle clonus. Plantar responses were extensor. Theexam of the sensory was normal except for a diminishedvibratory sensory in right leg. She was unable to walk ontip-toes and heels. Laboratory investigations showed ALT119 UI/I (7-31), AST 98 UI/I (10-38), and CK 728 UI/I(20-170). Thyroid function, vitamin B12, folate, and acomplete autoimmune profile were normal. Blood exami-nation showed no evidence of herpes virus, CMV, EBV,syphilis, borrelia, HIV-1/2, HTLV-1, or hepatotropic viru-ses. Brain MRI T2-weighted images and FLAIR revealed 8hyperintense lesions involving periventricular white matter,juxtacortical areas, and one left mesencephalic lesion,suggestive of demyelination. None of them demonstratedgadolinium enhancement. MRI of the whole spinal cord wasnormal (Fig. 1). Intrathecal IgG-oligoclonal bands werepresent in the cerebrospinal fluid examination and no ple-ocytosis. Visual-evoked potentials showed delayedresponses on both eyes. Nerve conduction studies werenormal but the results of the electromyography were con-sistent with a myopathic pattern; thus, a deltoid musclebiopsy was performed. Histopathology demonstrated thepresence of vacuoles with abnormal accumulation on peri-odic acid-Schiff (PAS) stain (Fig. 2). The enzyme activityin lymphocytes was 19.00 nmol 9 min 9 g (patient) ver-sus 614.00 nmol 9 min 9 g (controls), and was similarlylow in skin biopsy as well as in the muscle biopsy reliable toglycogen storage disease type 2. The analysis of the GAAgene found heterozygosity for IVS1-13T[G (also called c.-32-13T[G), a frequent pathogenic mutation among adultpatients with Pompe disease, as well as heterozygosity forthe unknown change M1L(1A[T), an unclassified variant.A liver biopsy confirmed the diagnosis of mild chronichepatitis. In the subsequent 2 years, the patient has suffereda progression in her symptoms. Although enzyme replace-ment therapy was started, her limb weakness has worsenedand she is able to walk with the assistance of a cane. NewsMRIs showed the presence of new T2-hyperintense whitematter lesions. According to McDonald’s criteria, a diag-nosis of primary progressive multiple sclerosis (PPMS) wasmade [1].MS and combined muscle disease has only beendescribed in a few case reports: a boy affected with cen-tronuclear myopathy who developed RRMS [2], a case ofcombined facio-scapulo-humeral muscular dystrophy [3],a case with combined myotonic dystrophy [4], and twocases of MS and mitochondrial myopathy [5]. This is thefirst report of a patient with both Pompe myopathy andmultiple sclerosis. Given the high prevalence of multiplesclerosis in our population, we consider that the associationbetween these two entities in our patient is casual. Pompe