Phases. Today is Rare Disease Day. I would like to use this opportunity to explain some of the phenotype science that is critical for rare diseases. In contrast to common disorders, rare diseases face an unusual challenge. Once identified, the overall rareness of these condition poses the question of where phenotypes begin and where they end. For rare genetic disorders, is the phenotype of the first individual identified with a rare disease characteristic, or is there a larger spectrum that we should be aware of? Enter the various approaches to phenotype science that aim to decipher the full depth of clinical features associated with rare diseases. In order to understand the various approaches to rare diseases phenotypes, I would like to suggest a somewhat unusual analogy: phenotypes are like water.
MAE. There are many distinct childhood epilepsy syndromes that we have become critically aware of in the genomic era as they are linked to prominent genetic causes, including Dravet Syndrome (SCN1A) and Epilepsy of Infancy with Migrating Focal Seizures (KCNT1). However, there are many other epilepsy syndromes where a genetic cause has long been suspected, but has remained elusive. One of the epilepsy syndromes that has largely remained unexplored is Doose Syndrome, also referred to as Myoclonic Astatic Epilepsy (MAE) or Epilepsy with Myoclonic-Atonic Seizures. In a recent study in Epilepsia, we explored the genetic architecture of Doose Syndrome and identified monogenic causes in 14% of individuals, including SYNGAP1, NEXMIF (KIAA2022), and SLC6A1. Our study suggests that Doose Syndrome is genetically heterogeneous, possibly with a distinct genetic landscape. Continue reading