IFIH1 and Spondyloenchondrodysplasia with immune dysregulation: This is true for all AGS mutant genes including IFIH1. Recently, the gene ACP5 encoding tartrate-resistant acid phosphatase (TRAP) was discovered for Spondyloenchondrodysplasia (SPENCD; MIM271550), a skeletal dysplasia syndrome with intracranial calcifications, spasticity, and immunologic abnormalities (Briggs et al. 2011).