ADAT3 is a non-catalytic regulatory subunit of the ADAT2/ADAT3 heterodimeric complex that catalyzes adenosine-to-inosine deamination at the wobble position (position 34) of tRNA anticodons 1. This modification is essential for translational decoding, as inosine-34 can pair with uracil, cytosine, and adenine at the third mRNA codon position, expanding codon recognition capacity 2. ADAT3 functions as a regulatory subunit required for proper complex assembly and tRNA substrate positioning; its N-terminus binds tRNA while its C-terminal domain forms part of the catalytic center with ADAT2 3. Beyond tRNA editing, the ADAT2/ADAT3 complex is critical for radial migration of cortical projection neurons during brain development, independent of its catalytic function 4. Loss-of-function ADAT3 variants cause autosomal recessive neurodevelopmental disorders characterized by intellectual disability, microcephaly, growth failure, strabismus, hypotonia, and dysmorphic features 5. ADAT3 mutations impair complex stability, nuclear localization, and catalytic activity, reducing tRNA wobble inosine levels with cascading effects on translational fidelity and neuronal development 4. Clinical significance includes ADAT3 variants accounting for approximately 26% of diagnosed Mendelian etiologies in cryptic cerebral palsy cohorts, making it an important diagnostic consideration 6.