Case studyA loss-of-function CACNA1A mutation causing benign paroxysmal torticollis of infancy

Benign paroxysmal torticollis of infancy (BPTI) is a rare paroxysmal disorder characterized by recurrent episodes of head tilt and accompanying general symptoms which remit spontaneously. The rare association with gain-of-function CACNA1A mutations, similar to hemiplegic migraine, has been reported. We report here two new BPTI patients from the same family carrying a heterozygous mutation in the CACNA1A gene leading to the change p.Glu533Lys. Functional analysis revealed that this mutation induces a loss of channel function due to impaired gating by voltage and much lower current density. Our data suggest that BPTI, a periodic syndrome commonly considered a migraine precursor, constitutes an age-specific manifestation of defective neuronal calcium channel activity.