Integrative Transcriptomic Analysis and Preliminary Peripheral Blood Evaluation Identify ASAP2 as an Exploratory Candidate Molecule Associated with Complete Androgen Insensitivity Syndrome.

BACKGROUND

Complete androgen insensitivity syndrome (CAIS) is a rare 46,XY disorder/difference of sex development (DSD) caused by impaired androgen receptor (AR) function. Although AR sequencing is central to diagnosis, downstream transcriptional consequences of AR dysfunction and accessible readouts of androgen-pathway disruption remain unclear.

METHODS

Two CAIS-related RNA-seq datasets from the Gene Expression Omnibus (GEO) were analyzed separately rather than merged at the expression-matrix level. GSE125222 included testicular tissue from 3 CAIS cases and 3 normal-spermatogenesis controls on GPL20301/Illumina HiSeq 4000. GSE300211 included 64 genital skin fibroblast libraries from 12 control and 4 CAIS fibroblast lines treated with ethanol or 10 nM dihydrotestosterone for 48 or 72 h on GPL30173/NextSeq 2000. Differential expression analysis, weighted gene co-expression network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO), random forest, and support vector machine-recursive feature elimination (SVM-RFE) were used to prioritize exploratory candidate genes. ASAP2 mRNA expression and ASAP2 protein abundance were further examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting, respectively, in peripheral blood mononuclear cells (PBMCs) from an independent pilot cohort (3 CAIS patients and 3 controls). Gene set enrichment analysis (GSEA) and CIBERSORTx were used to explore associated pathways and immune features.

RESULTS

ASAP2 was consistently downregulated in CAIS testicular tissue and patient-derived fibroblasts and was prioritized as an exploratory candidate molecule. In the pilot PBMC cohort, ASAP2 mRNA and ASAP2 protein levels were also reduced in CAIS. ASAP2-associated genes were enriched in pathways related to cytoskeletal remodeling, antigen processing and presentation, tumor necrosis factor signaling, and NOD-like receptor signaling. Immune deconvolution suggested altered immune-cell composition in CAIS tissue and associations between ASAP2 expression and several immune-cell subsets.

CONCLUSION

ASAP2 represents a CAIS-associated exploratory candidate with preliminary peripheral detectability. These findings support further investigation of downstream molecular networks after AR deficiency and possible androgen-pathway disruption. They do not establish ASAP2 as a clinical diagnostic biomarker. Larger multicenter cohorts, relevant 46,XY DSD comparators, and functional studies are required to clarify whether ASAP2 can serve as a surrogate readout of broader androgen-pathway disruption.