Pyridoxine-dependent Epilepsy (PDE) is a rare autosomal recessive disorder causing intractable seizures in neonates and infants. It is characterized by seizures that are resistant to common anticonvulsants, but patients respond well to the administration of pyridoxine. PDE is caused by ALDH7A1 genetic defect. Here, we report the disease-causative variant in the ALDH7A1 gene in two affected Tunisian families. Direct sequencing analysis revealed a novel missense mutation c.1364T>C (p.Leu455Pro). Using bioinformatic tools we suggested that this variant may have deleterious effects on ALDH7A1 protein structure and function.