Further evidence of a causal association between AGO1, a critical regulator of microRNA formation, and intellectual disability/autism spectrum disorder

Among the many regulators of microRNA formation, Argonaute 1 (AGO1) plays critical roles in RNA interference, which controls a wide range of biological activities. Recent large-scale genomic studies have identified at least five patients with intellectual disability/autism spectrum disorder who had de novo mutations in AGO1, but detailed clinical information was not available. The recognizable clinical features that are associated with AGO1 mutations remain to be determined. The proposita was a 15-year-old girl with diffuse hypotonia, infrequent seizures, and intellectual disability with an intelligence quotient of 41. She had characteristic facial features consisting of telecanthus, wide nasal bridge with bulbous nasal tip, and a round face with downslanted palpebral fissures. Serial computed tomography scans showed progressive calcification in the globus pallidus that became evident during childhood. A whole exome analysis in trio revealed a de novo heterozygous mutation in AGO1, i.e., c.595G > A p.(Gly199Ser). The distinctive facial features, i.e., telecanthus, wide nasal bridge with bulbous nasal tip, and a round face with downslanted palpebral fissures, closely resembled previously reported patients who had a chromosomal microdeletion encompassing AGO1 locus. The combinatory phenotype of such characteristic facial features and radiographic features, i.e. progressive calcification in the globus pallidus, in the presently reported patient suggest that AGO1 mutations lead to a syndromic form of intellectual disability/autism spectrum disorder. Distinctive facial features with early and progressive calcification in the globus pallidus may be suggestive of the presence of AGO1 mutations.