Pathogenic variants in CDC45 on the remaining allele in patients with a chromosome 22q11.2 deletion result in a novel autosomal recessive condition

Abstract

PurposeThe 22q11.2 deletion syndrome (22q11.2DS) is the most common microdeletion in humans, with highly variable phenotypic expression. Whereas congenital heart defects, palatal anomalies, immunodeficiency, hypoparathyroidism, and neuropsychiatric conditions are observed in over 50% of patients with 22q11DS, a subset of patients present with additional “atypical” findings such as craniosynostosis and anorectal malformations. Recently, pathogenic variants in the CDC45 (Cell Division Cycle protein 45) gene, located within the LCR22A–LCR22B region of chromosome 22q11.2, were noted to be involved in the pathogenesis of craniosynostosis. MethodsWe performed next-generation sequencing on DNA from 15 patients with 22q11.2DS and atypical phenotypic features such as craniosynostosis, short stature, skeletal differences, and anorectal malformations. ResultsWe identified four novel rare nonsynonymous variants in CDC45 in 5/15 patients with 22q11.2DS and craniosynostosis and/or other atypical findings. ConclusionThis study supports CDC45 as a causative gene in craniosynostosis, as well as a number of other anomalies. We suggest that this association results in a condition independent of Meier–Gorlin syndrome, perhaps representing a novel condition and/or a cause of features associated with Baller–Gerold syndrome. In addition, this work confirms that the phenotypic variability observed in a subset of patients with 22q11.2DS is due to pathogenic variants on the nondeleted chromosome.