Moyamoya and progressive myoclonic epilepsy secondary to CLN6 bi-allelic mutations - A previously unreported association

Abstract

The neuronal ceroid lipofuscinoses (NCL) are a collection of lysosomal storage diseases characterised by the accumulation of characteristic inclusions containing lipofuscin in various tissues of the body and are one of the causes of progressive myoclonic epilepsy. Mutations in at least thirteen genes have been identified as causes of NCL, which can present as infantile, late-infantile, juvenile or adult forms. CLN6 codes for an endoplasmic reticulum transmembrane protein of unknown function. Homozygous and compound heterozygous mutations of the gene are associated with both late-infantile (LINCL) and adult onset (ANCL) forms of NCL, including Kufs disease, comprising ANCL without associated visual loss. Moyamoya, a rare vasculopathy of the circle of Willis, has been reported in conjunction with a number of inflammatory and other diseases, as well as a handful of lysosomal storage diseases. To our knowledge, this is the first reported case of Moyamoya in the context of the neuronal ceroid lipofuscinoses or a CLN6-related disease.

Keywords: ANCL; ANCL, adult neuronal ceroid lipofuscinosis; BMIPB, the Brain Injury Rehabilitation Trust Memory and Information Processing Battery; CLN6; Kufs disease; LINCL, late-infantile neuronal ceroid lipofuscinosis; MERRF, mitochondrial epilepsy with ragged red fibres; Moyamoya; NCL; NCL, neuronal ceroid lipofuscinosis; Neuronal ceroid lipofuscinosis; PPT1, palmitoyl-protein thioesterase 1; SEP, somatosensory evoked potentials; TPP1, tripeptidyl peptidase 1; WAIS-IV, Wechsler Adult Intelligence Scale (4th edition); Wiegl, Weigl Color Form Sorting Test; mtDNA, mitochondrial DNA.

Fig. 1

a) Awake EEG showing left central spike discharges. b) Seizure onset with head version to the right and posturing of the left arm.

Fig. 2

Nerve conduction studies. a) Presence of the C- reflex after stimulation of the left and (b) right median nerves c) Giant SEPs.

Fig. 3

a) and b) FLAIR sequences showing T2 hyperintense lesions in the right cerebral hemisphere. c), d) and e) Magnetic resonance angiogram sequences showing stenoses of distal internal carotid arteries (white arrow) and proximal middle cerebral arteries with collateral vessel formation (red arrow).