Unverricht-Lundborg Disease in Turkey: Delineating The Phenotype Between Cystatin B Mutation Positive and Negative Cases

Objective: We herein report the first three genetically proven Unverricht-Lundborg disease (ULD) patients in Turkey and their clinical comparisons with eight CSTB mutation negative patients who were suspected to have ULD.Materials and Methods: Eleven progressive myoclonic epilepsy (PME) patients were included with a presumptive clinical diagnosis of ULD. All patients were examined physically, neurologically, psychiatrically and questioned about their daily activities. During the follow-up, clinical, EEG and MRI data were analyzed. Genomic DNA was extracted from peripheral blood of each patient by standard procedures, after signed informed consent and analyzed for mutations in CSTB.Results: Two ULD patients were homozygous for the dodecamer repeat expansion mutation, while the third was compound heterozygous for the expansion and a novel nonsense mutation in exon 2 of CSTB. The ULD patients appeared to have more cerebro-cerebellar atrophy in their MRIs, psychiatric problems, more prominent cognitive defects and they needed more often help in their daily activities. The background activity in their EEGs seemed slower and the EEGs had more pronounced generalized epileptiform activity and photosensitivity. They had myoclonia, which was more sensitive to external stimuli including visual stimulation. Complex partial and absence seizures as presenting symptoms were only present in the mutation negative patients. This group tended to be misdiagnosed as juvenile myoclonic epilepsy or focal epilepsy, whereas all ULD patients were diagnosed as idiopathic generalized epilepsy before reaching the final diagnosis during follow-up.Conclusions: However there are no clearly differentiating features between the CTSB mutation negative and positive cases.