STXBP1 and neurodevelopmental disorder: Conversely, when assessing recurrent variants and hotspots, none of the major recurrent variants in STXBP1 had significant phenotypic similarity, in contrast to main recurrent variants in other neurodevelopmental disorders such as SCN2A-related disorders.32 This suggests that despite observed trends of recurrent variants with specific phenotypic features (see below), the baseline variability of phenotypic features is too high to allow for discrete clinical subgroups to be recognized.