aScan: A Novel Method for the Study of Allele Specific Expression in Single Individuals

A compendium of methods: Searching allele specific expression via RNA sequencing

Diploid mammalian genome has paired alleles for each gene; typically allowing for equal expression of the two alleles within the cell/tissue. However, genetic regulatory elements and epigenetic modifications can disrupt this equality, leading to preferential expression of one allele. Examining high-confidence allele-specific expression (ASE) is vital for understanding genetic variations and their impact on major diseases like cancers and diabetes. ASE analysis not only aids in disease prognosis and diagnosis but also helps to identify regulatory mechanisms operating within the genome. While advances in sequencing technologies have greatly improved our understanding of ASE, challenges remain in estimating it accurately. In this article, we reviewed methods for detecting ASE using both bulk RNASeq and single-cell RNASeq data to provide deeper insights beyond the mere prediction of ASE genes. Fundamentally, ASE detection methods are data-driven and can be classified according to type of data used. Some methods utilize both, DNA genotyping information and RNASeq while others rely solely on RNASeq data. This article offers a comparative analysis of these methods and compilation of repositories providing valuable insights.

Characterizing the allele-specific gene expression landscape in high hyperdiploid acute lymphoblastic leukemia with BASE

Somatic copy number variations (CNVs), including abnormal chromosome numbers and structural changes leading to gain or loss of genetic material, play a crucial role in initiation and progression of cancer. CNVs are believed to cause gene dosage imbalances and modify cis-regulatory elements, leading to allelic expression imbalances in genes that influence cell division and thereby contribute to cancer development. However, the impact of CNVs on allelic gene expression in cancer remains unclear. Allele-specific expression (ASE) analysis, a potent method for investigating genome-wide allelic imbalance profiles in tumors, assesses the relative expression of two alleles using high-throughput sequencing data. However, many existing methods for gene-level ASE detection rely on only RNA sequencing data, which present challenges in interpreting the genetic mechanisms underlying ASE in cancer. To address this issue, we developed a robust framework that integrates allele-specific copy number calls into ASE calling algorithms by leveraging paired genome and transcriptome data from the same sample. This integration enhances the interpretability of the genetic mechanisms driving ASE, thereby facilitating the identification of driver events triggered by CNVs in cancer. In this study, we utilized BASE to conduct a comprehensive analysis of ASE in high hyperdiploid acute lymphoblastic leukemia (HeH ALL), a prevalent childhood malignancy characterized by gains of chromosomes X, 4, 6, 10, 14, 17, 18, and 21. Our analysis unveiled the comprehensive ASE landscape in HeH ALL. Through a multi-perspective examination of HeH ASEs, we offer a systematic understanding of how CNVs impact ASE in HeH, providing valuable insights to guide ASE studies in cancer.

Study on Allele Specific Expression of Long-Term Residents in High Altitude Areas

In diploid organisms, half of the chromosomes in each cell come from the father and half from the mother. Through previous studies, it was found that the paternal chromosome and the maternal chromosome can be regulated and expressed independently, leading to the emergence of allele specific expression (ASE). In this study, we analyzed the differential expression of alleles in the high-altitude population and the normal population based on the RNA sequencing data. Through gene cluster analysis and protein interaction network analysis, we found some changes occurred at the gene level, and some negative effects. During the study, we realized that the calmodulin homology domain may have a certain correlation with long-term survival at high altitude. The plateau environment is characterized by hypoxia, low air pressure, strong ultraviolet radiation, and low temperature. Accordingly, the genetic changes in the process of adaptation are mainly reflected in these characteristics. High altitude generation living is also highly related to cancer, immune disease, cardiovascular disease, neurological disease, endocrine disease, and other diseases. Therefore, the medical system in high altitude areas should pay more attention to these diseases.