Clinical and genetic features in pyridoxine-dependent epilepsy: a Chinese cohort study

Abstract

Aim: To characterize the clinical and genetic characteristics of a large cohort of patients with pyridoxine-dependent epilepsy (PDE). Method: We retrospectively collected clinical and genetic information of 33 (15 males, 18 females; mean [SD] age 4y 11mo [2y 5mo]; 1y 3mo–10y 4mo) patients with PDE from 31 unrelated families at a single centre. Results: There were many types of seizures, with focal seizures in 32 cases. Dravet syndrome was suspected clinically in two patients. Electroencephalogram (EEG) was normal in seven patients at the initial stage and then in 17 patients during pyridoxine maintenance therapy. Genetic studies revealed 26 kinds of variants in ALDH7A1 and four in PLPBP with 18 variants unreported previously, and 48 ALDH7A1 variants were located in exon 11, 12, 14, and 17 or intron 9 and 11. In addition, three patients carried different exons deletion. Among these, seizures could be controlled for several years in one patient by levetiracetam monotherapy. Another patient remained seizure free for up to 7 months without therapy. All patients received oral pyridoxine treatment, with only one case (with exon 8–13 deletion) showing poor control. Interpretation: This study illustrates the range of clinical presentations and genetic causes in PDE, as well as responsiveness to antiepileptic drugs. A relationship between EEG and pyridoxine therapy could be seen in many cases. Seizure control was seen in all with pyridoxine monotherapy except for one patient. What this paper adds: There is a parallel relationship between electroencephalogram and pyridoxine therapy in many patients. Patients with pyridoxine-dependent epilepsy may respond well to low-dose pyridoxine.