Loss of SYNJ1 dual phosphatase activity leads to early onset refractory seizures and progressive neurological decline
Abstract
SYNJ1 encodes a polyphosphoinositide phosphatase (Synaptojanin 1) with a prominent role in synaptic vesicle dynamics. Hardies et al. report three families (six patients) with autosomal recessive SYNJ1 variants, who display early-onset refractory seizures and progressive neurological decline.
The pathogenic variants entail loss of the dual phosphatase activity of Synaptojanin 1.SYNJ1 encodes a polyphosphoinositide phosphatase (Synaptojanin 1) with a prominent role in synaptic vesicle dynamics. Hardies et al. report three families (six patients) with autosomal recessive SYNJ1 variants, who display early-onset refractory seizures and progressive neurological decline.
The pathogenic variants entail loss of the dual phosphatase activity of Synaptojanin 1.SYNJ1 encodes a polyphosphoinositide phosphatase, synaptojanin 1, which contains two consecutive phosphatase domains and plays a prominent role in synaptic vesicle dynamics. Autosomal recessive inherited variants in SYNJ1 have previously been associated with two different neurological diseases: a recurrent homozygous missense variant (p.Arg258Gln) that abolishes Sac1 phosphatase activity was identified in three independent families with early onset parkinsonism, whereas a homozygous nonsense variant (p.Arg136*) causing a severe decrease of mRNA transcript was found in a single patient with intractable epilepsy and tau pathology.
We performed whole exome or genome sequencing in three independent sib pairs with early onset refractory seizures and progressive neurological decline, and identified novel segregating recessive SYNJ1 defects.