Abstract
BACKGROUND: Central nervous system features have been rarely described to be associated with the small deletion or duplication of chromosome 22q11.21. CASE PRESENTATION: We report two patients with chromosome 22q11.21 alterations and central nervous system abnormalities. Features described include semilobar holoprosencephaly in the patient with the small deletion and Chiari I malformation in the patient with the small duplication. CONCLUSIONS: This report will aid in the characterization of the clinical significance of interstitial duplications and deletions on the long-arm of chromosome 22. Areas of future research would benefit from additional analysis of the described regions with inclusion of the phenotypic findings described in this case report to provide additional insight into the pathogenicity of the described alterations.