The present phenotype-based disease classification causes ambiguity in diagnosing and determining timely, effective treatment options for primary immunodeficiency (PID).

In this study, we aimed to examine the characteristics of early-onset PID and proposed a JAK-STATopathy subgroup based on their molecular defects.

We reviewed 72 patients (< 100 days) retrospectively. These patients exhibited various immune-related phenotypes and received a definitive molecular diagnosis by next-generation sequencing (NGS)-based tests.

We evaluated the PID-causing genes and clinical parameters. We assessed the genes that shared the JAK-STAT signalling pathway.

We also examined the potential high risks related to the 180-day death rate.