Systematic functional validation of IKAROS variants from patients and laboratory-generated mutations.

Area of Science:

• Immunology
• Genetics
• Molecular Biology

Background:

• The transcription factor IKAROS is crucial for lymphocyte development and acts as a tumor suppressor.
• Over 70 IKAROS germline variants are linked to primary immunodeficiency (PID)/inborn errors of immunity (IEI) and leukemia.
• Germline IKAROS mutations can cause immunodeficiency, immune dysregulation, and hematologic malignancies.

Purpose of the Study:

• To functionally characterize variants of uncertain significance (VUS) in IKAROS.
• To determine the impact of mutations in the IKAROS C-terminal dimerization domain.
• To provide a comprehensive analysis of 81 IKAROS variants for clinical relevance.

Main Methods:

• Systematic in vitro testing of IKAROS function using generated constructs.
• Alanine-scanning mutagenesis of the IKAROS C-terminal dimerization domain.
• Analysis of 33 patient-detected VUS and 48 laboratory-generated mutations.

Main Results:

• 15 patient-detected IKAROS variants, mainly in DNA-binding or dimerization domains, impaired function.
• At least 21 laboratory-generated mutations in the dimerization domain impaired IKAROS function.
• Variants between DNA-binding and dimerization domains were less likely to be deleterious.

Conclusions:

• Functional data on IKAROS variants can explain or result in human disease.
• This study identifies deleterious IKAROS mutations relevant for diagnosing PID/IEI and leukemia.
• Findings assist in patient diagnosis and guide treatment decisions for IKAROS-related disorders.