SDHB and hyperinsulinemic hypoglycemia, familial, 4: Recently, immunohistochemistry for the detection of an intact SDH complex has been used to triage genetic SDH deficiency in PGL, and utilized by groups working in the GIST field to solidify the involvement of the SDH complex in the oncogenesis of pediatric and syndromic GISTs, as well as a subset of adult WT GISTs.