CD3G gene defects in familial autoimmune thyroiditis.

Area of Science:

• Immunology
• Genetics

Background:

• CD3γ deficiency is a rare primary immunodeficiency affecting T-cell function.
• The CD3G gene encodes the gamma subunit of the T-cell receptor complex, crucial for T-cell signaling.

Observation:

• This study investigates five CD3γ-deficient siblings from two families with a shared homozygous CD3G mutation (c.80-1G>C).
• Patients exhibited diverse clinical presentations and cellular phenotypes, including combined T-B+NK+ immunodeficiency.
• Autoimmunity was a prominent feature, observed in all five patients and frequently in heterozygous carriers.

Findings:

• All patients presented with at least one autoimmune condition, including autoimmune thyroiditis, hemolytic anemia, and immune thrombocytopenia.
• Low CD3(+) TCRαβ+ T cell percentages were noted in all patients.
• A significant prevalence of autoimmunity (67%) was observed in heterozygous carriers, indicating a potential role for CD3G in immune regulation beyond complete deficiency.

Implications:

• The findings suggest CD3G should be considered a candidate gene for autoimmune disorders.
• CD3γ deficiency warrants consideration within the differential diagnosis of primary immunodeficiencies presenting with autoimmune manifestations.
• Further research into the role of CD3γ in immune homeostasis and autoimmunity is warranted.