Progressive myoclonus epilepsy and ceroidolipofuscinosis 14: The multifaceted phenotypic spectrum of KCTD7-related disorders

BACKGROUND: Mutations in the KCTD7 gene have been associated with progressive myoclonus epilepsy and, in a single patient, with the so-called "Neuronal Ceroid Lipofuscinosis 14" (characterised by myoclonic seizures, cognitive regression, optic atrophy leading to visual loss, and progressive cortical and cerebellar atrophy). CLINICAL REPORTS: We describe two new patients carrying two novel pathogenic mutations in the KCTD7 gene. Patient 1 (NM_153033.4: c.[533C > T], NP_694578: p.[(Ala178Val)]) was a 17-year-old girl who presented with early-onset epilepsy resembling epilepsia partialis continua (responsive to intravenous corticosteroids and immunoglobulins), and later developed myoclonic seizures and atypical absences, photosensitivity to very low frequencies and progressive seizures-related neurocognitive and motor deterioration. Patient 2 (NM_153033.4: c.[172G>A], NP_694578: p.[(Gly58Arg)]) presented with early neurological regression, myoclonic seizures and lysosomal storage material which was consistent with a neuronal ceroid lipofuscinosis (NCL) at skin biopsy. Both patients had non epileptic myoclonus. CONCLUSIONS: The two reported patients carrying novel pathogenic variants in KCTD7 gene presented with a remarkable phenotypic heterogeneity including: a) progressive myoclonus epilepsy without NCL-type lysosomal storages; b) progressive myoclonus epilepsy with lysosomal storages resembling NCL pattern (NCL14); c) progressive myoclonus epilepsy with epilepsia partialis continua. myoclonic seizures, cognitive regression, optic atrophy leading to visual loss, and progressive cortical and cerebellar atrophy).