Genetic Diagnosis Using Whole Exome Sequencing in Common Variable Immunodeficiency

Area of Science:

• Genetics
• Immunology
• Molecular Biology

Background:

• Whole exome sequencing (WES) is effective for identifying genetic defects in primary immunodeficiencies (PIDs).
• The genetic basis of common variable immunodeficiency (CVID) remains challenging to elucidate.
• A structured approach is needed to leverage WES for CVID genetic diagnosis.

Purpose of the Study:

• To establish a practical framework for utilizing WES to identify causative genetic mutations in CVID patients.
• To assess the efficacy of WES combined with PID-gene analysis in a cohort of CVID subjects.

Main Methods:

• WES was performed on 50 CVID patients meeting specific criteria (e.g., early onset, autoimmune issues, low B cells).
• Exomes were screened for mutations in 269 known PID-associated genes.
• Variants were filtered by inheritance pattern, population frequency, segregation analysis, and computational predictions.

Main Results:

• Seventeen probable disease-causing mutations were identified in 15 patients (30% diagnostic yield).
• Identified mutations included monoallelic variants in NFKB1, STAT3, CTLA4, PIK3CD, IKZF1 and biallelic variants in LRBA, STXBP2.
• Forty-two other damaging variants were noted but deemed unlikely to cause disease based on phenotype and inheritance.

Conclusions:

• WES coupled with PID-gene analysis is a cost-effective method for diagnosing CVID, particularly in severe cases.
• This diagnostic approach successfully identified causative mutations in 30% of the studied CVID cohort.
• Improved genetic diagnosis through WES can enhance the management of CVID patients, especially with the advent of targeted therapies.