STXBP2 and microvillus inclusion disease: In Pagel et al.’s initial paper describing gastrointestinal manifestations in patients with STXBP2-associated HLH, the absence of chronic diarrhea was linked to the presence of an exon 15 splice-site mutation, p.Val417Leufs*126; however, a later case report described a patient homozygous for this allele with chronic diarrhea and MVID-like symptoms (Pagel et al. 2012; Dhekne et al. 2018).