Combined Immunodeficiency Due To Zap70 Deficiency Watchlist (log in to enable) Retrieved 2021-01-23 Source Orphanet Trials — Genes ZAP70, CYBB, PNP, NCF1 Drugs — Interested in hearing about new therapies? Registered! A very rare, severe, genetic, combined immunodeficiency disorder characterized by lymphocytosis, decreased peripheral CD8+ T-cells, and presence of normal circulating CD4+ T-cells, leading to immune dysfunction.