Tricho-Hepato-Enteric Syndromic Immunodeficiency: Clinical Spectrum, Pathobiology, and Emerging Therapies.

BACKGROUND: Syndromic inborn errors of immunity (IEIs) are a heterogeneous group of disorders characterized by immune dysfunction associated with congenital anomalies and multisystem involvement. Tricho-hepato-enteric syndrome (THES) is an ultra-rare autosomal recessive syndromic IEI caused by biallelic pathogenic variants in TTC37 or SKIV2L. Delayed recognition is common because of its broad clinical spectrum. OBJECTIVES: To describe the clinical, immunologic, genetic, and histopathologic characteristics of two children with THES and to highlight a structured diagnostic approach for syndromic immunodeficiencies. METHODS: We retrospectively reviewed the clinical presentation, laboratory investigations, immune phenotyping, endoscopic and histopathologic findings, and molecular analyses of two unrelated children diagnosed with THES at a tertiary pediatric immunology center. Molecular confirmation was obtained by whole-exome sequencing. RESULTS: Both patients presented during early infancy with intractable diarrhea, severe failure to thrive, characteristic dysmorphic features, brittle woolly hair, and inflammatory enteropathy requiring prolonged nutritional support. Immunologic evaluation demonstrated immune dysregulation, including inverted CD4/CD8 ratios, abnormalities of humoral immunity, and impaired vaccine-specific antibody responses. Histopathology revealed chronic active colitis with crypt distortion, inflammatory infiltrates, and crypt abscesses, consistent with very-early-onset inflammatory bowel disease-like enteropathy. Whole-exome sequencing identified homozygous pathogenic variants in SKIV2L in one patient and TTC37 in the other, establishing the diagnosis. Management included nutritional support, immunoglobulin replacement, antimicrobial prophylaxis, and immunomodulatory therapy. CONCLUSIONS: Recognition of syndromic phenotype combined with comprehensive immune evaluation and early genomic testing facilitates prompt diagnosis, multidisciplinary management, genetic counseling, and consideration of emerging targeted therapies.