Expanding the phenotype of reciprocal 1q21.1 deletions and duplications: a case series

Background: Recurrent reciprocal 1q21.1 deletions and duplications have been associated with variable phenotypes. Phenotypic features described in association with 1q21.1 microdeletions include developmental delay, craniofacial dysmorphism and congenital anomalies. The 1q21.1 reciprocal duplication has been associated with macrocephaly or relative macrocephaly, frontal bossing, hypertelorism, developmental delay, intellectual disability and autism spectrum disorder. Methods: Our study describes seven patients, who were referred to us for developmental delay/intellectual disability, dysmorphic features and, in some cases, congenital anomalies, in whom we identified 1q21.1 CNVs by array-CGH. Results: Our data confirm the extreme phenotypic variability associated with 1q21.1 microdeletion and microduplication. We observed common phenotypic features, described in previous studies, but we also described, for the first time, congenital hypothyroidism in association with 1q21.1 deletion and trigonocephaly associated with 1q21.1 duplication. Conclusions: The aim of this study is to contribute to the definition of the phenotype associated with reciprocal 1q21.1 deletions and duplications.