By linkage analysis, we mapped the disease to chromosome 5q23.2-q23.3, within a 4.3 Mb genomic region containing LMNB1. We demonstrated that lamin B1 mRNA expression in ADLD-1-TO patients was increased and comparable to the expression levels found in ADLD patients with LMNB1 duplication (9,21,22). This evidence concerns the gene LMNB1 and adult-onset autosomal dominant demyelinating leukodystrophy.