Genotypes and phenotypes of patients with Lafora disease living in Germany

Background Lafora progressive myoclonus epilepsy (Lafora disease) is a rare, usually childhood-onset, fatal neurodegenerative disease caused by biallelic mutations inEPM2A(Laforin) orEPM2B(NHLRC1; Malin).The epidemiology of Lafora disease in Germany is largely unknown. The objective of this retrospective case series is to characterize the genotypes and phenotypes of patients with Lafora disease living in Germany. Methods The patients described in this case series initially had the suspected clinical diagnosis of Lafora disease, or unclassified progressive myoclonus epilepsy. Molecular genetic diagnostics including next generation sequencing-based diagnostic panel analysis or whole exome sequencing was performed. Results The parents of four out of the 11 patients are nonconsanguineous and of German origin while the other patients had consanguineous parents. Various variants were found inEPM2A(six patients) and inEPM2B(five patients). Eight variants have not been reported in the literature so far. The patients bearing novel variants had typical disease onset during adolescence and show classical disease courses. Conclusions This is the first larger case series of Lafora patients in Germany. Our data enable an approximation of the prevalence of manifest Lafora disease in Germany to 1,69 per 10 million people. Broader application of gene panel or whole-exome diagnostics helps clarifying unclassified progressive myoclonus epilepsy and establish an early diagnosis, which will be even more important as causal therapy approaches have been developed and are soon to be tested in a phase I study.