Third, >95% of TCRαβ+ DN cells in CD4-deficient patients could be defined as conventional DN cells (CD38−CD45+/−), as observed for healthy donors, rather than pathogenic DN (CD38+CD45+/−) cells that are enriched (50%) in FAS deficiency. The gene discussed is PTPRC; the disease is hyperinsulinemic hypoglycemia, familial, 4.