Identification of a novel nonsense homozygous mutation of LINS1 gene in two sisters with intellectual disability, schizophrenia, and anxiety

Domain-specific phenotypes in LINS1-related disorder-A Chinese family with the Q92X variant and literature review

LINS1 is the human homolog of the Drosophila segment polarity gene that encodes an essential regulator of the wingless/Wnt signaling. By 2011, only seven pedigrees (16 patients) with eight causative variants in LINS1 gene have been reported. These cases mainly presented with infancy-/child-onset neurodevelopmental disorders, facial dysmorphia, and other clinical features, and a wide spectrum of clinically distinct phenotypes were also manifested. In our study, two brothers in a family were admitted and diagnosed with child-onset movement disorders, slight intellectual disability, psychological symptoms, eye problems, urinary and bowel dysfunction, mitral value prolapse, and Q-T prolongation. By exome sequencing, we identified a nonsense homozygous pathogenic variant (LINS1: c.274C > T (p.Q92X)), which had been reported in a case diagnosed with intellectual disability and psychiatric disorders (such as schizophrenia and anxiety). Compared with this case, the clinical features of our cases were distinct. In particular, our cases displayed unusual features of heart and blood system. Furthermore, the genotype-phenotype relationship analysis suggested that distinct phenotypes presented in cases carrying variants in different domains of the LINS1 gene. In conclusions, our findings suggest the high clinical variations in the LINS1 variants-related disorders. Moreover, the Q92X might be a recurrent variant in Hans of Southern China.

Whole Genome Sequencing Revealed Inherited Rare Oligogenic Variants Contributing to Schizophrenia and Major Depressive Disorder in Two Families

Schizophrenia and affective disorder are two major complex mental disorders with high heritability. Evidence shows that rare variants with significant clinical impacts contribute to the genetic liability of these two disorders. Also, rare variants associated with schizophrenia and affective disorders are highly personalized; each patient may carry different variants. We used whole genome sequencing analysis to study the genetic basis of two families with schizophrenia and major depressive disorder. We did not detect de novo, autosomal dominant, or recessive pathogenic or likely pathogenic variants associated with psychiatric disorders in these two families. Nevertheless, we identified multiple rare inherited variants with unknown significance in the probands. In family 1, with singleton schizophrenia, we detected four rare variants in genes implicated in schizophrenia, including p.Arg1627Trp of LAMA2, p.Pro1338Ser of CSMD1, p.Arg691Gly of TLR4, and Arg182X of AGTR2. The p.Arg691Gly of TLR4 was inherited from the father, while the other three were inherited from the mother. In family 2, with two affected sisters diagnosed with major depressive disorder, we detected three rare variants shared by the two sisters in three genes implicated in affective disorders, including p.Ala4551Gly of FAT1, p.Val231Leu of HOMER3, and p.Ile185Met of GPM6B. These three rare variants were assumed to be inherited from their parents. Prompted by these findings, we suggest that these rare inherited variants may interact with each other and lead to psychiatric conditions in these two families. Our observations support the conclusion that inherited rare variants may contribute to the heritability of psychiatric disorders.

Two Genetic Mechanisms in Two Siblings with Intellectual Disability, Autism Spectrum Disorder, and Psychosis

Intellectual disability (ID) and autism spectrum disorder (ASD) are complex neurodevelopmental disorders with high heritability. To search for the genetic deficits in two siblings affected with ID and ASD in a family, we first performed a genome-wide copy number variation (CNV) analysis using chromosomal microarray analysis (CMA). We found a 3.7 Mb microdeletion at 22q13.3 in the younger sister. This de novo microdeletion resulted in the haploinsufficiency of SHANK3 and several nearby genes involved in neurodevelopment disorders. Hence, she was diagnosed with Phelan–McDermid syndrome (PMS, OMIM#606232). We further performed whole-genome sequencing (WGS) analysis in this family. We did not detect pathogenic mutations with significant impacts on the phenotypes of the elder brother. Instead, we identified several rare, likely pathogenic variants in seven genes implicated in neurodevelopmental disorders: KLHL17, TDO2, TRRAP, EIF3F, ATP10A, DICER1, and CDH15. These variants were transmitted from his unaffected parents, indicating these variants have only moderate clinical effects. We propose that these variants worked together and led to the clinical phenotypes in the elder brother. We also suggest that the combination of multiple genes with moderate effects is part of the genetic mechanism of neurodevelopmental disorders.

After me, the deluge: The intricacies of pulmonary surfactant

This issue of the Biomedical Journal provides a comprehensive insight into the role of pulmonary surfactant and influencing its components as well as involved molecules to treat a variety of respiratory distress disorders. We also discover how epithelial mesenchymal transition (EMT) could be targeted as part of a therapeutic strategy against lung cancer. Furthermore, a method is described to eliminate chemoresistance against gemcitabine, a drug administered to treat pancreatic cancer. We gain an insight into the composition of salivary calcium particles in periodontitis, a technique to circumvent complications in hip surgery, and a potential treatment to accelerate diabetic wound healing. Moreover, we get to know an essential oil that exerts a similar effect as diazepam on the central nervous system. A trial in patients with myofascial pain syndrome demonstrates how laser assisted trigger point therapy leads to immediate relief. Finally, a case study outlines the discovery of a genetic mutation that plays a role in intellectual disability.