Diverse immune phenotype patterns were detected in AHD and N-AHD patients: AHD presented higher CD8+ (AHD: 59, IQR 51–66—N-AHD 48, IQR 41–57; P = 0.0001), lower CD127+CD4+ (median CD127+CD4+%: AHD 6, IQR 3–11—N-AHD 15, IQR 10–22; P = 0.0001), higher CD95+CD8+ (median CD95+CD8+%: AHD 3, IQR 2–6—N-AHD 2, IQR 1–3; P = 0.0001), CD38+CD8+ (median CD38+CD8+%: AHD 11, IQR 3–25—N-AHD 5, IQR 2–10; P = 0.0001), and CD45R0+CD38+CD8+ (median CD45R0+CD38+CD8+%: AHD 14, IQR 10–25—N-AHD 11, IQR 7–19; P = 0.008) percentages in comparison to N-AHD (Table 3(b)). The gene discussed is IL7R; the disease is mitochondrial DNA depletion syndrome 4a.