Our study presents the first reported case of the patients with missense mutation in the RAI1 gene whose HL is not accompanied by specific traits (variable intellectual disability, speech and motor delay, self-injurious and/or aggressive behavior, sleep disturbance, particular craniofacial and skeletal abnormalities, obesity, hearing loss, hoarse voice and other less common characteristic traits) typical for Smith-Magenis syndrome (SMS). The gene discussed is RAI1; the disease is Smith-Magenis syndrome.