Unusual course of Lafora disease

A 42-year-old male was admitted for refractory status epilepticus. At the age of 25, he had been diagnosed with juvenile myoclonic epilepsy. He had a stable clinical course for over a decade until a recent deterioration of behavior and epilepsy. After exclusion of acquired disorders, diagnostic work-up included application of next-generation sequencing (NGS), with a gene panel targeting progressive myoclonic epilepsies. This resulted in the diagnosis Lafora disease resulting from compound heterozygous NHLRC1 pathogenic variants. Although these pathogenic variants may be associated with a variable phenotype, including both severe and mild clinical course, the clinical presentation of our patient at this age is very unusual for Lafora disease. Our case expands the phenotype spectrum of Lafora disease resulting from pathogenic NHLRC1 variants and illustrates the value of using NGS in clinical practice to lead to a rapid diagnosis and guide therapeutic option

Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth's D" layer

The Earth's lower mantle is believed to be composed mainly of (Mg,Fe)SiO3 perovskite, with lesser amounts of (Mg,Fe)O and CaSiO3). But it has not been possible to explain many unusual properties of the lowermost 150 km of the mantle (the D" layer) with this mineralogy. Here, using ab initio simulations and high-pressure experiments, we show that at pressures and temperatures of the D" layer, MgSiO3 transforms from perovskite into a layered CaIrO3-type post-perovskite phase. The elastic properties of the post-perovskite phase and its stability field explain several observed puzzling properties of the D" layer: its seismic anisotropy, the strongly undulating shear-wave discontinuity at its top and possibly the anticorrelation between shear and bulk sound velocities.Comment: PUBLISHED IN Nature 430, 445-448 (2004