<i>NONO</i> (<i>Non-Pou Domain-Containing Octamer-Binding Protein</i>) gene maps on chromosome Xq13.1 and hemizygous loss-of-function nucleotide variants are associated with an emerging syndromic form of intellectual developmental disorder (MRXS34; MIM #300967), characterized by developmental delay, intellectual disability, poor language, dysmorphic facial features, and microcephaly. The gene discussed is NONO; the disease is microcephaly.