Immune-mediated inflammatory polyneuropathy overlapping Charcot-Marie-Tooth 1B.

Charcot Marie Tooth (CMT) due to myelin protein zero (MPZ) mutations, may cause a wide variation of phenotypes, depending on the localization of the mutation within the gene. Among the most common phenotypes are: an infantile onset disease with extremely slow nerve conduction velocities (CMT1B) and an adult onset phenotype with nerve velocities in the axonal range (CMT2I). We reported a patient with CMT1B (MPZ p.Ser63del mutation) which developed an overlapping immune mediated polyradiculoneuropathy with recurrent episodes of quadriparesis and cranial nerve involvement. We observed reversible conduction block on serial neurophysiologic studies, non-uniform demyelination and good clinical response to prednisone and cyclophosphamide, as evidenced by objective functional recovery. Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)-like characteristics have not yet been described associated with a MPZ p.Ser63del mutation. This description adds evidence indicating that a defective structural myelin protein may predispose peripheral nerves to immune attacks.

Motor unit number index (MUNIX) in myopathic disorders: Clinical correlations and potential pitfalls.

Our aim was to study motor unit number index (MUNIX) in myopathic disorders. We studied 11 patients with myopathy, and healthy controls. We obtained MUNIX, compound muscle action potential (CMAP), motor unit size index (MUSIX) and alpha (α, power exponent from MUNIX equation) measurements from three different muscles. MUNIX and CMAP were significantly lower in one muscle. This MUNIX decrease may not be related to motor neuron loss, but rather to muscle fiber atrophy. MUSIX and α did not change and may be useful in determining whether the MUNIX decrease is indeed due to motor unit loss.

Leukodystrophy with disorders of sex development due to WT1 mutations.

BACKGROUND: Hypomyelinating leukodystrophies represent an expanding group of neurogenetic disorders characterized primarily by central nervous system hypomyelination and variable neurological and non-neurological involvement. Hypomyelinating disorders have been rarely associated with gonadal dysfunction, being mainly represented by hypogonadotrophic hypogonadism in 4H syndrome. WT1 gene-associated disorders are classically associated with complex phenotypes including early carcinogenic risk for gonadoblastoma and Wilms' tumor, chronic renal failure, nephrotic syndrome and sex developmental disorders in intersex disorders and ambiguous genitalia. METHODS: The authors describe three non-related Brazilian patients with hypomyelinating leukodystrophy associated with complex neurological and systemic dysfunction with WT1 gene mutations. RESULTS: All described patients presented with similar neuroimaging features including thin corpus callosum, mild to moderate cerebellar atrophy and diffuse periventricular and profound hypomyelinating leukodystrophy involving supratentorial white matter with classical compromise linked to inherited non-somatic WT1 gene mutations in a similar pattern to Denys-Drash syndrome, including nephrotic syndrome with different glomerular disease, chronic renal failure, intersex disorder with ambiguous genitalia, and early occurrence of specific tumors, such as Wilms' tumor and gonadoblastoma. CONCLUSIONS: Clinicians must include WT1 gene mutations in the differential diagnosis of hypomyelinating leukodystrophy with nephrotic syndrome, chronic renal failure, ambiguous genitalia or sex developmental disorders.