Prenatally detected encephalocele associated with a novel pathogenic TCTN3 variant: A case report and literature review.

Primary cilia are a component of almost all vertebrate cells with a crucial role in sensing and transducing environmental signals during tissue development. Their dysfunction is known as ciliopathies and can manifest with a wide spectrum of clinical disorders. Overlapping features and molecular heterogeneity of ciliopathies make diagnoses distinctly challenging. In this group of diseases, tectonic genes, and their mutations play an important role. We present a first-trimester fetus with occipital encephalocele and OFD type IV caused by TCTN3 compound heterozygous pathogenic variants: c.1423_1429del (p.Arg475Serfs*10) and c.3G>A (initiator codon). A severe arm anomaly was described in our case, with two fingers along the atrophic forearm and polydactyly on other limbs. This could be a new phenotypic characteristic contributing to further understanding of TCTN3-related disorders as well as other tectonic proteins in ciliopathy spectrum diseases.