At MedGenome, we are deeply focused on continuous innovation, and publishing our findings for the larger benefit of the genetic testing community. Read through our publications for details of our latest work.
Novel GNAL mutation in an Indian patient with generalized dystonia and response to deep brain stimulation
Date: January 14, 2019
Mutations in GNAL have been associated with cranio-cervical dystonia (DYT-GNAL) [ 1 ]. The dystonia most often progresses to involve other regions, particularly the face and laryngeal muscles and less commonly the trunk, arm and lower limbs. The clinical phenotype in GNAL-related dystonia appears to be similar to that caused by mutations in THAP1
Differential methylation of the type 2 diabetes susceptibility locus KCNQ1 is associated with insulin sensitivity and is predicted by CpG site specific genetic variation.
Date: January 11, 2019
Epigenetic mechanisms regulate gene expression and may influence the pathogenesis of type 2 diabetes through the loss of insulin sensitivity. The aims of this study were to measure variation in DNA methylation at the type 2 diabetes locus KCNQ1 and assess its relationship with metabolic measures and with genotype.
Date: December 21, 2018
A large number of tumor intrinsic and extrinsic factors determine long-term survival in human cancers. In this study, we stratified 9120 tumors from 33 cancers with respect to their immune cell content and identified immunogenomic features associated with long-term survival. Our analysis demonstrates that tumors infiltrated by CD8+ T cells expressing higher levels of activation marker (PD1hi) along with TCR signaling genes and cytolytic T cell markers (IL2hi/TNF-αhi/IFN-γhi/GZMA-Bhi) extend survival, whereas survival benefit was absent for tumors infiltrated by anergic and hyperexhausted CD8+ T cells characterized by high expression of CTLA-4, TIM3, LAG3, and genes linked to PI3K signaling pathway. The computational approach of using robust and highly specific gene expression signatures to deconvolute the tumor microenvironment has important clinical applications, such as selecting patients who will benefit from checkpoint inhibitor treatment.
Date: November 11, 2018
Retinoblastoma (RB) is a childhood eye cancer. Currently, chemotherapy, local therapy, and enucleation are the main ways in which these tumors are managed. The present work is the first study that uses constraint‐based reconstruction and analysis approaches to identify and explain RB‐specific survival strategies, which are RB tumor specific. Importantly, our model‐specific secretion profile is also found in RB1‐depleted human retinal cells in vitro and suggests that novel biomarkers involved in lipid metabolism may be important. Finally, RB‐specific synthetic lethals have been predicted as lipid and nucleoside transport proteins that can aid in novel drug target development.
Date: October 25, 2018
Deregulated HER2 is a target of many approved cancer drugs. We analyzed 111,176 patient tumors and identified recurrent mutations in HER2 transmembrane domain (TMD) and juxtamembrane domain (JMD) that include G660D, R678Q, E693K, and Q709L. Using a saturation mutagenesis screen and testing of patient-derived mutations we found several activating TMD and JMD mutations. Structural modeling and analysis showed that the TMD/JMD mutations function by improving the active dimer interface or stabilizing an activating conformation. Further, we found that HER2 G660D employed asymmetric kinase dimerization for activation and signaling. Importantly, anti-HER2 antibodies and small-molecule kinase inhibitors blocked the activity of TMD/JMD mutants. Consistent with this, a G660D germline mutant lung cancer patient showed remarkable clinical response to HER2 blockade.
Is there a Chance to Promote Arteriogenesis by DPP4 Inhibitors Even in Type 2 Diabetes? A Critical Review.
Date: October 22, 2018
Cardiovascular diseases (CVD) are still the prevailing cause of death not only in industrialized countries, but even worldwide. Type 2 diabetes mellitus (type 2 DM) and hyperlipidemia, a metabolic disorder that is often associated with diabetes, are major risk factors for developing CVD. Recently, clinical trials proved the safety of gliptins in treating patients with type 2 DM. Gliptins are dipeptidyl-peptidase 4 (DPP4/CD26) inhibitors, which stabilize glucagon-like peptide-1 (GLP-1), thereby increasing the bioavailability of insulin. Moreover, blocking DPP4 results in increased levels of stromal cell derived factor 1 (SDF-1). SDF-1 has been shown in pre-clinical animal studies to improve heart function and survival after myocardial infarction, and to promote arteriogenesis, the growth of natural bypasses, compensating for the function of an occluded artery. Clinical trials, however, failed to demonstrate a superiority of gliptins compared to placebo treated type 2 DM patients in terms of cardiovascular (CV) outcomes. This review highlights the function of DPP4 inhibitors in type 2 DM, and in treating cardiovascular diseases, with special emphasis on arteriogenesis. It critically addresses the potency of currently available gliptins and gives rise to hope by pointing out the most relevant questions that need to be resolved.
A neoepitope derived from a novel human germline APC gene mutation in familial adenomatous polyposis shows selective immunogenicity
Date: September 26, 2018
Familial adenomatous polyposis (FAP) is an inherited condition arising from genetic defects in the Adenomatous polyposis coli (APC) gene. Carriers with mutations in the APC gene develop polyps in the colon and rectum which if not managed, transition into colon cancer. In this study, we identified a novel germline mutation in the APC gene in members of an FAP-affected (Familial adenomatous polyposis) family. This unique heterozygous variant (c.735_736insT; p.Ser246PhefsTer6) was identified in ten out of twenty six family members, ranging in age from 6 to 60 years. Polyps were detected in six of the ten individuals (35–60 years) carrying this mutation. The remaining four members (6–23 years) remain polyp free. A significant fraction of FAP affected individuals eventually develop colon cancer and therapeutic interventions to prevent cancer progression remain elusive. To address this issue, we sought to determine if peptides derived from the novel APC mutation could induce a cytotoxic T cell response, thereby qualifying them as vaccine candidates. Peptides harboring the variant amino acids were first interrogated in silico for their immunogenicity using a proprietary neoepitope prioritization pipeline, OncoPeptVAC. A single 9-mer peptide was predicted to be immunogenic. Remarkably, CD8+ T cells isolated from either an FAP+/ APCmut individual, or from a FAP-/ APCmut individual, failed to respond to the peptide, whereas those from either an unaffected family member (FAP-/ APCwt) or from healthy unrelated donors, showed a robust response, suggesting that CD8+ T cells from individuals carrying this germline APC mutation have been tolerized to the mutation. Furthermore, experimental testing of six additional reported APC gene mutation-derived peptides revealed one of the six to be immunogenic. While not all APC mutant peptides are inmmunogenic, a few qualify as vaccine candidates offering novel treatment opportunities to patients with somatic APC gene mutations to delay/treat colorectal cancer.
Date: August 27, 2018
Mutations in the myofibrillogenesis regulator gene (MR-1) causes paroxysmal non -kinesigenic dyskinesia (PNKD) characterized by episodic (paroxysmal) attacks of any combination of chorea, dystonia and athetosis ( MR-1/PNKD) [ 1 ]. This gene is transcribed into three alternatively spliced isoforms: long (MR-1L), medium (MR-1M) and small (MR-1S) [ 2 , 3 ]. Three mutations namely, A7V, A9V and A33P have been described in the N-terminal region common to MR-1L and MR-1S, but not MR-1M and are reported to segregate with the disease in unrelated PNKD families [ 3 , 4 ]. PNKD mutations may also be a cause for familial Tourette syndrome
Date: August 14, 2018
Snigdha Majumder, Rakshit Shah, Jisha Elias, Malini Manoharan, Priyanka Shah, Anjali Kumari, Papia Chakraborty, Vasumathi Kode, Yogesh Mistry, Karunakaran Coral, Bharti Mittal, Sakthivel Murugan SM, Lakshmi Mahadevan, Ravi Gupta, Amitabha Chaudhuri & Arati Khanna-Gupta. Lynch Syndrome (LS) is an inherited heterozygous autosomal dominant disorder which predisposes affected individuals to the risk of developing colorectal cancer (CRC) as well as to endometrial carcinomas, tumours of the stomach, small intestines, ureter, brain, pelvis and prostate among others1. It is the most common hereditary CRC syndrome accounting for 2–5% of all CRCs. In the developed world, the estimated disease frequency ranges from 1:370 to 1:20002 but no prevalence details have been officially reported from developing nations to date. In India, while the overall incidence of CRC is comparatively lower than in the west, a large percentage of patients develop CRC before the age of 45 with a higher proportion (10–15%) of LS-CRC cases3.
Identification of deletion-duplication in HEXA gene in five children with Tay-Sachs disease from India
Date: July 4, 2018
“Background Tay-Sachs disease (TSD) is a sphingolipid storage disorder caused by mutations in the HEXA gene. To date, nearly 170 mutations of HEXA have been described, including only one 7.6 kb large deletion. Methods Multiplex Ligation-dependent Probe Amplification (MLPA) study was carried out in 5 unrelated patients for copy number changes where heterozygous and/or homozygous disease causing mutation/s could not be identified in the coding region by sequencing of HEXA gene. Results The study has identified the presence of a homozygous deletion of exon-2 and exon-3 in two patients, two patient showed compound heterozygosity with exon 1 deletion combined with missense mutation p.E462V and one patient was identified with duplication of exon-1 with novel variants c.1527-2A > T as a second allele. Conclusion This is the first report of deletion/duplication in HEXA gene providing a new insight into the molecular basis of TSD and use of MLPA assay for detecting large copy number changes in the HEXA gene.”””