Clinical and genetic features of CTLA-4 haploinsufficiency: a prospective study in China

Heterozygous loss-of-function variants in CTLA4 cause a spectrum of immune dysregulation, characterized by hypogammaglobulinemia, autoimmune cytopenias, and lymphoproliferation, yet penetrance and expressivity remain highly variable across cohorts. To characterize the clinical, genetic, and therapeutic features of a prospective Chinese cohort with CTLA-4 haploinsufficiency, and to compare their management outcomes with those reported in the largest international series. Seven patients diagnosed by whole-exome sequencing underwent systematic evaluation of clinical phenotypes, laboratory parameters, imaging and histopathology, and treatment responses. Data were contrasted against the largest global cohort of CTLA-4 haploinsufficiency. All individuals harbored heterozygous CTLA4 variants, four missense and three truncating mutations, exhibiting classical features of immune dysregulation alongside marked phenotypic heterogeneity, even among family members with identical genotypes. The median diagnostic delay from the first symptom onset to genetic confirmation was 8 years (range: 2–50 years). Importantly, for patients who initiated targeted therapy (P1, P2, P3, P5, and P6), abatacept was administered within a median of less than one year following molecular diagnosis, demonstrating the high clinical efficiency enabled by our prospective screening approach. Nearly all patients received abatacept achieving sustained disease stabilization and tapering of corticosteroids, complemented by IVIG to correct hypogammaglobulinemia. Proactive family screening identified asymptomatic carriers, underscoring the value of genetic counseling for at-risk relatives. This study demonstrates that early genetic screening coupled with prompt abatacept-based immunomodulation and IVIG replacement can markedly shorten diagnostic latency, stabilize multi-system disease.These findings provide a model for precision-medicine approaches in diverse populations.