KIRREL3-related disorders: a case report confirming the radiological features and expanding the clinical spectrum to a less severe phenotype

Background: Neurodevelopmental disorders have a multifactorial etiology, since biological, genetic, psychosocial and environmental risk factors are involved. Recent studies have been linking neurodevelopmental disorders and intellectual disability with a variety of genes, some of which encoding neuronal cell-adhesion molecules. Among these, KIRREL3 is known to play a role in CNS development, and his variants have recently been related to intellectual disability, autism spectrum disorder, childhood apraxia of speech, cerebellar hypoplasia and mild dysmorphic features. Case presentation: In this study, we describe a young Caucasian boy with mild intellectual disability, cerebellar anomalies (cerebellar hypoplasia and mega cisterna magna) and minor dysmorphic features associated to a novel KIRREL3 variant. Conclusions: Aim of the present case report is to expand the clinical spectrum of KIRREL3-related diseases towards a milder phenotype than what is already described in the literature. We speculate that the interaction between KIRREL3 and CASK might play a major role in promoting cognitive and cerebellar development, contributing to a variety of clinical manifestations.