Epileptic encephalopathy with continuous spike‐and‐wave during sleep maps to a homozygous truncating mutation in AMPA receptor component FRRS1L

Fig. 1. (a) Updated pedigree of the original family. Red arrow indicates the index whose DNA was exome sequenced, blue triangles indicate cases 1 and 2 in the original publication, and red asterisks (*) denote individuals whose DNA was available for analysis and segregation. (b) AgileMultiIdeogram image reveals a single autozygous block on chromosome 9 that is exclusive to the affected members in the family, which is further confirmed by linkage analysis. (c) Sequence chromatogram of the nonsense mutation and control tracing shown for comparison as well as a cartoon of the FRRS1L gene and encoded protein with the position of the mutation indicated by blue triangles. characterized by continuous or near-continuous slow spike and waves, and the occurrence of slow-spike-wave during a significant proportion of non-REM sleep. CSWS presents with seizures, usually focal-clonic and out of sleep, and neurocognitive regression (2). The usual age of onset is 2–4 years of age and the differential diagnosis includes Landau-Kleffner