Introduction: VULTO-VAN SILFHOUT-DE VRIES SYNDROME (VSVS;OMIM#615828) is an extremely rare hereditary disease associated with impaired intellectual development and speech, delayed psychomotor development and behavioral anomalies, including autistic behavioral traits and poor eye contact. To date, 27 patients with VSVS have been reported in the world literature. Materials and Methods: We describe a 23y.o. male patient with autism spectrum disorder (ASD) who was admitted to the gastroenterological hospital with signs of pseudomembranous colitis. ASD was first noted in the patient at the age of 2.5y.o. Later he developed epileptic seizers and prominent growth retardation. Prior to the hospitalization he was excluded chromosomal aberrations, Martin-Bell syndrome, aminoacidopathies/aminoacidurias associated with ASD. Whole genome sequencing was prescribed to the patient at 23y.o. Results: The patient appeared to be a heterozygous carrier of “de novo” variant c.662C>T (p.S221L) in ex 4 of the DEAF1 gene. c.662C> T had not been previously described in genomic databases. According to the ACMG criteria this missense variant was considered to be pathogenic. VSVS was diagnosed in the patient. Conclusions: The phenotype of the patient is very similar to the data presented in the world literature. However, growth retardation and cachexia, not previously described in the articles, are of interest.