MAGT1 and early-onset autosomal dominant Alzheimer disease: The FRMD4B (FERM domain containing 4B) gene, associated with cognitive function determinants,55 is also linked to brain volume, both in healthy populations and multiple sclerosis patients.56,57 Additionally, the FRMD4B gene was implicated in the myelination network in late-onset of Alzheimer disease.58 The MAGT1 gene encodes a protein that regulates intracellular Mg2 and protein glycosylation.