Confirmation of mutations in PROSC as a novel cause of vitamin B 6 -dependent epilepsy.
Plecko BDivision of Child Neurology, University Children's Hospital Zurich, Zurich, Switzerland.
Zweier MInstitute of Medical Genetics, University of Zurich, Zurich, Switzerland.
Begemann Aradiz - "Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases University of Zurich", University of Zurich, Zurich, Switzerland.
Mathis DClinical Chemistry, University Children's Hospital Zurich, Zurich, Switzerland.
Schmitt BDivision of Child Neurology, University Children's Hospital Zurich, Zurich, Switzerland.
Striano PPediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, G. Gaslini Institute, Genova, Italy.
Vari MSPediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, G. Gaslini Institute, Genova, Italy.
Beccaria FChild Neuropsychiatry, C. Poma Hospital, Mantova, Italy.
Zara FIRCCS, University of Genova, G. Gaslini Institute, Genova, Italy.
Crowther LMDivision of Child Neurology, University Children's Hospital Zurich, Zurich, Switzerland.
Joset PInstitute of Medical Genetics, University of Zurich, Zurich, Switzerland.
Sticht HInstitute of Biochemistry, University of Erlangen-Nuernberg, Erlangen, Germany.
Papuc SMradiz - "Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases University of Zurich", University of Zurich, Zurich, Switzerland.
Rauch Aradiz - "Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases University of Zurich", University of Zurich, Zurich, Switzerland.
English
Vitamin-B6-dependent epilepsies are a heterogenous group of treatable disorders due to mutations in several genes (ALDH7A1, PNPO, ALPL or ALDH4A1). In neonatal seizures, defects in ALDH7A1 and PNPO explain a major fraction of cases. Very recently biallelic mutations in PROSC were shown to be a novel cause in five families. We identified four further unrelated patients harbouring a total of six different mutations, including four novel disease mutations. Vitamin B6 plasma profiles on pyridoxine did not enable the differentiation of patients with PROSC mutations. All four patients were normocephalic and had normal cranial imaging. Pyridoxine monotherapy allowed complete seizure control in one, while two patients had occasional febrile or afebrile seizures and one needed additional valproate therapy for photosensitive seizures. Two patients underwent a controlled pyridoxine withdrawal with signs of encephalopathy within a couple of days. Three had favourable outcome with normal intellectual properties at age 12.5, 15.5 and 30 years, respectively, while one child had marked developmental delay at age 27 months. The clinical and electroencephalographic phenotype in patients with PROSC mutations was indistinguishable from ALDH7A1 and PNPO deficiency. We therefore confirm PROSC as a novel gene for vitamin-B6-dependent epilepsy and delineate a non-specific plasma vitamin B6 profile under pyridoxine treatment.