Background: Leber congenital amaurosis (LCA) is a rare inherited retinal disease causing severe visual impairment in infancy. It has been reported that 9-15% of LCA cases have mutations in CRB1 gene. The complex of CRB1 protein with other associated proteins affects the determination of cell polarity, orientation, and morphogenesis of photoreceptors. Here, we report three novel pathogenic variants in CRB1 gene and then briefly review the types, prevalence, and correlation of reported mutations in CRB1 gene. Methods: Whole exome sequencing and targeted gene panel were employed. Then validation in the patient and segregation analysis in affected and unaffected members was performed. Results: Our detected novel pathogenic variants (p.Glu703*, c.2128+1G>A and p.Ser758SerfsX33) in CRB1 gene were validated by Sanger sequencing. Segregation analysis confirmed the inheritance pattern of the pathogenic variants. Conclusion: Our findings show that emerging the next-generation sequencing-based techniques is very efficient in identifying causative variants in disorders with locus heterogeneity.

Intellectual disability is the most common neurodevelopmental defect in the worldwide. X-linked intellectual disability (XLID) is the frequent form of intellectual disability which includes a heterogeneous group of inherited disorders emerging as various degrees of intellectual disabilities. XLID has a prevalence of 2.6 cases per 1,000 in the general population and accounts for over 10% of all cases of intellectual disability. Based on associated phenotypes, XLID is subdivided into syndromic (S-XLID) and non-syndromic (NS-XLID) forms; where two third of XLID cases are thought to be non-syndromic. Among the non-syndromic form, the aristalessrelated homeobox gene (ARX) gene is one of the ideal candidates to be evaluated in NS-XLID, since its mutations are responsible for about 9.5% of XLID cases. The ARX is located on the Xp22.13 genomic region and encodes a highly conserved protein with a considerable role in Wnt/β-catenin signaling pathway. Base on review literature, mutations in ARX gene has a particular influence on the critical processes associated with the brain development. Our results in bioinformatics study of molecular features, second and quaternary structures of ARX gene and also the phylogeny tree of ARX protein is showed that the ARX is a highly conserved protein with a substantial role in an important developmental pathway and its deficiency can cause irreversible defects, mainly in brain, that leads to the development of XLID as a common form of intellectual disability and also, the sequence alignment of this protein with other spices confirms that the functional domains of ARX protein are highly conserved, thus it has been predicted that the mutations of this gene is highly pathogenic. Alongside, we mainly focused to gather the data addressing the structural properties of ARX protein and bioinformatics assay of this protein to find the important role of ARX gene in the integrity of normal brain development.

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Background: Dilated cardiomyopathy (DCM) is a progressive heart condition characterized by left ventricular chamber enlargement associated with systolic heart failure and prolonged action potential duration. Genetic variations in genes that encode cytoskeleton, sarcomere, and nuclear envelope proteins are responsible for 45% of cases. In our study, we focused on a pedigree with familial DCM to decipher the potential genetic cause(s) in affected members developing arrhythmia, end-stage heart failure, and sudden death. Methods: Whole-exome sequencing (WES) was exploited for a 27-year-old heart-transplanted female as the proband, and the derived data were filtered using the standard pipelines. Results: A 57-nucleotide deletion (c.405_422+39del) in the desmoplakin gene (DSP) (NM_004415.4) was identified as a novel pathogenic variant. Familial segregation analysis indicated that this variant is present in clinically affected members and absent in unaffected members. Conclusions: It seems that the detected variant induces intron retention, resulting in a premature stop codon in intron 3 of DSP leading to production of a truncated, nonfunctional protein. Additionally, it can trigger a nonsense-mediated mRNA decay pathway associated with inhibition of protein production. The present study results illustrated that a novel deletion in DSP can cause DCM in an Iranian family.