A VAPB (P56S) mutation in a Dutch patient with familial motor neuron disease: a case report.

The c.166C > T p.(Pro56Ser) or P56S mutation in the VAPB gene was initially identified as a cause of motor neuron disease in Brazil in a large extended pedigree comprising >1,500 individuals including more than 200 cases. This VAPB mutation gives rise to three phenotypes: late-onset spinal muscular atrophy, classical ALS with bulbar involvement, pyramidal signs and rapid disease progression, and atypical ALS with slow progression. Nearly all known cases originate from a single founder, with most cases outside of Brazil being related to this pedigree. However, there is one report of an independent German family with the same mutation on a different haplotype, indicating a second founder event. Here, we report the first Dutch patient with a P56S mutation in VAPB and motor neuron disease. Documenting rare genetic causes of MND and their natural history are of increasing importance in light of emerging gene-specific therapies.