Getting to know adenosine deaminase 2 deficiency inside and out

Area of Science:

• Immunology
• Genetics
• Cell Biology

Background:

• Adenosine deaminase (ADA2) deficiency (DADA2) is a rare genetic disorder with diverse clinical manifestations.
• Despite a decade since initial descriptions, the cellular mechanisms underlying DADA2 remain poorly understood.
• The focus has shifted intracellularly with the discovery of ADA2 protein's lysosomal localization and nucleic acid sensing role.

Purpose of the Study:

• To review the characteristics and proposed functions of the ADA2 protein.
• To explore potential cellular mechanisms driving the diverse clinical phenotypes in DADA2 patients.
• To discuss established and novel pathways in DADA2 pathogenesis.

Main Methods:

• Literature review of studies on ADA2 protein characteristics and function.
• Analysis of existing data on DADA2 patient cohorts, clinical phenotypes, and genotype-phenotype correlations.
• Discussion of proposed intracellular and extracellular roles of ADA2 in disease pathogenesis.

Main Results:

• ADA2 protein is localized to lysosomes and involved in nucleic acid sensing.
• Extracellular ADA2 enzyme activity remains the diagnostic standard, despite intracellular focus.
• Weak genotype-phenotype correlations complicate understanding of shared cellular mechanisms.

Conclusions:

• Understanding ADA2's intracellular functions is crucial for elucidating DADA2 pathogenesis.
• Further research into cellular mechanisms is needed to explain inflammation, immunodeficiency, and bone marrow failure in DADA2.
• Exploring novel pathways may offer new therapeutic targets for DADA2.