A microcephalic osteodysplastic primordial dwarfism that has material basis in homozygous or compound heterozygous mutation in the RNU4ATAC gene, encoding a small nuclear RNA (snRNA) component of the U12-dependent (minor) spliceosome, on chromosome 2q14.2. It is characterized by dwarfism, microcephaly, and neurologic abnormalities, including mental retardation, brain malformations, and ocular, auditory sensory deficits.