Mutations in MINAR2 encoding membrane integral NOTCH2-associated receptor 2 cause deafness in humans and mice.

Discovery of deafness genes and elucidating their functions have substantially contributed to our understanding of hearing physiology and its pathologies. Here we report on DNA variants in MINAR2, encoding membrane integral NOTCH2-associated receptor 2, in four families underlying autosomal recessive nonsyndromic deafness. Neurologic evaluation of affected individuals at ages ranging from 4 to 80 y old does not show additional abnormalities. MINAR2 is a recently annotated gene with limited functional understanding. We detected three MINAR2 variants, c.144G > A (p.Trp48*), c.412_419delCGGTTTTG (p.Arg138Valfs*10), and c.393G > T, in 13 individuals with congenital- or prelingual-onset severe-to-profound sensorineural hearing loss (HL). The c.393G > T variant is shown to disrupt a splice donor site. We show that Minar2 is expressed in the mouse inner ear, with the protein localizing mainly in the hair cells, spiral ganglia, the spiral limbus, and the stria vascularis. Mice with loss of function of the Minar2 protein (Minar2tm1b/tm1b) present with rapidly progressive sensorineural HL associated with a reduction in outer hair cell stereocilia in the shortest row and degeneration of hair cells at a later age. We conclude that MINAR2 is essential for hearing in humans and mice and its disruption leads to sensorineural HL. Progressive HL observed in mice and in some affected individuals and as well as relative preservation of hair cells provides an opportunity to interfere with HL using genetic therapies.

Dispersed DNA variants underlie hearing loss in South Florida's minority population.

BACKGROUND: We analyzed the genetic causes of sensorineural hearing loss in racial and ethnic minorities of South Florida by reviewing demographic, phenotypic, and genetic data on 136 patients presenting to the Hereditary Hearing Loss Clinic at the University of Miami. In our retrospective chart review, of these patients, half self-identified as Hispanic, and the self-identified racial distribution was 115 (86%) White, 15 (11%) Black, and 6 (4%) Asian. Our analysis helps to reduce the gap in understanding the prevalence, impact, and genetic factors related to hearing loss among diverse populations. RESULTS: The causative gene variant or variants were identified in 54 (40%) patients, with no significant difference in the molecular diagnostic rate between Hispanics and Non-Hispanics. However, the total solve rate based on race was 40%, 47%, and 17% in Whites, Blacks, and Asians, respectively. In Non-Hispanic Whites, 16 different variants were identified in 13 genes, with GJB2 (32%), MYO7A (11%), and SLC26A4 (11%) being the most frequently implicated genes. In White Hispanics, 34 variants were identified in 20 genes, with GJB2 (22%), MYO7A (7%), and STRC-CATSPER2 (7%) being the most common. In the Non-Hispanic Black cohort, the gene distribution was evenly dispersed, with 11 variants occurring in 7 genes, and no variant was identified in 3 Hispanic Black probands. For the Asian cohort, only one gene variant was found out of 6 patients. CONCLUSION: This study demonstrates that the diagnostic rate of genetic studies in hearing loss varies according to race in South Florida, with more heterogeneity in racial and ethnic minorities. Further studies to delineate deafness gene variants in underrepresented populations, such as African Americans/Blacks from Hispanic groups, are much needed to reduce racial and ethnic disparities in genetic diagnoses.

Deletion of first noncoding exon in ANKRD11 leads to KBG syndrome.

Phenotypic features of KBG syndrome include craniofacial anomalies, short stature, cognitive disability and behavioral findings. The syndrome is caused by heterozygous pathogenic single nucleotide variants and indels in ANKRD11, or a heterozygous deletion of 16q24.3 that includes ANKRD11. We performed genome sequencing on a patient with clinical manifestations of KBG syndrome including distinct craniofacial features as well as a history of mild intellectual disability and attention-deficit hyperactivity disorder. This led to the identification of a 43 kb intragenic deletion of ANKRD11 affecting the first noncoding exon while leaving the coding regions intact. Review of the literature shows that this is the smallest 5' deletion affecting only the noncoding exons of ANKRD11. Real-time polymerase chain reaction demonstrated that the copy number variant was not present in either of the proband's parents, suggesting it occurred de novo. RNA expression analysis demonstrated significantly decreased transcript abundance compared to controls. This provides new evidence for haploinsufficiency as a mechanism of disease in KBG syndrome.

Anti-arthritogenic and cardioprotective action of hesperidin and daidzein in collagen-induced rheumatoid arthritis.

Atherosclerosis has been linked to chronic inflammatory processes. Changes in the levels of lipoproteins, especially low-density lipoprotein or its variants, as well as inflammatory markers are risk factors for the atherosclerosis. In the present study, an experimental model of rheumatoid arthritis was developed by administrating collagen suspension intradermally in the tail region of Wistar albino rats. At the same time, a suspension of hesperidin (50 mg/kg body weight) and daidzein (20 mg/kg body weight) was orally administrated. The compounds were given in the morning and evening for 21 days. Levels of inflammatory markers in the homogenate of knee joints of experimental rats as well as plasma lipoproteins were investigated. The administration of hesperidin and daidzein caused significant (p < 0.001) decrease in articular elastase activity, TNF-α, and malondialdehyde levels. Further, arthritis scoring and histological findings supported the anti-inflammatory actions of the test compounds. Interestingly, the test compounds also lowered the plasma low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and triglyceride but increased the level of high-density lipoprotein cholesterol. The test compounds thus ameliorated the risk factors of atherosclerosis. Furthermore, antioxidant roles of hesperidin as well as daidzein were evident from decrease in free radical load demonstrated as increase in total antioxidant level in plasma of arthritic animals treated with hesperidin and daidzein. In a separate in vitro experiment, enhanced free radical scavenging activity of hesperidin was demonstrated against 2,2-diphenyl-1-picrylhydrazyl and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid. The anti-inflammatory, hypolipidemic, and antioxidant actions of the naturally occurring test compounds, particularly hesperidin, seem to be quite effective against rheumatoid arthritis and atherosclerosis. Thus, their consumption may be helpful in prevention or at least delaying the onset of these diseases in susceptible individuals.

Assessment of genotoxic induction and deterioration of fish quality in commercial species due to heavy-metal exposure in an urban reservoir.

The aim of the study was to evaluate the effect of heavy-metal contamination on two fish species (Channa striatus and Heteropneustes fossilis) inhabiting a small freshwater body of northern India. After being captured, each specimen was weighed, measured, and analyzed for heavy metals (chromium [Cr], nickel [Ni], and lead [Pb]). Accumulation of heavy metals was found to be significantly greater (p < 0.05) in different tissues (gill, liver, kidney, and muscle) of fishes captured from the reservoir than from the reference site. Levels of heavy-metal contamination in Shah jamal water was Cr (1.51 mg/l) > Ni (1.22 mg/l) > Pb (0.38 mg/l), which is significantly greater than World Health Organization standards. Bioaccumulation factor was calculated, and it was observed that Pb was most detrimental heavy metal. Condition factor was also influenced. Micronucleus test of fish erythrocytes and comet assay of liver cells confirmed genotoxicity induced by heavy-metal contamination in fishes. Heavy metals (Cr, Ni, and Pb) were increased in both fish species as determined using recommended values of Federal Environmental Protection Agency for edible fishes. This raises a serious concern because these fishes are consumed by the local populations and hence would ultimately affect human health.

Human Organoids for Rapid Validation of Gene Variants Linked to Cochlear Malformations.

Developmental anomalies of the hearing organ, the cochlea, are diagnosed in approximately one-fourth of individuals with congenital deafness. Most patients with cochlear malformations remain etiologically undiagnosed due to insufficient knowledge about underlying genes or the inability to make conclusive interpretations of identified genetic variants. We used exome sequencing for genetic evaluation of hearing loss associated with cochlear malformations in three probands from unrelated families. We subsequently generated monoclonal induced pluripotent stem cell (iPSC) lines, bearing patient-specific knockins and knockouts using CRISPR/Cas9 to assess pathogenicity of candidate variants. We detected FGF3 (p.Arg165Gly) and GREB1L (p.Cys186Arg), variants of uncertain significance in two recognized genes for deafness, and PBXIP1(p.Trp574*) in a candidate gene. Upon differentiation of iPSCs towards inner ear organoids, we observed significant developmental aberrations in knockout lines compared to their isogenic controls. Patient-specific single nucleotide variants (SNVs) showed similar abnormalities as the knockout lines, functionally supporting their causality in the observed phenotype. Therefore, we present human inner ear organoids as a tool to rapidly validate the pathogenicity of DNA variants associated with cochlear malformations.

Genetic heterogeneity in hereditary hearing loss: Potential role of kinociliary protein TOGARAM2.

Hearing loss (HL) is a heterogenous trait with pathogenic variants in more than 200 genes that have been discovered in studies involving small and large HL families. Over one-third of families with hereditary HL remain etiologically undiagnosed after screening for mutations in the recognized genes. Genetic heterogeneity complicates the analysis in multiplex families where variants in more than one gene can be causal in different individuals even in the same sibship. We employed exome or genome sequencing in at least two affected individuals with congenital or prelingual-onset, severe to profound, non-syndromic, bilateral sensorineural HL from four multiplex families. Bioinformatic analysis was performed to identify variants in known and candidate deafness genes. Our results show that in these four families, variants in a single HL gene do not explain HL in all affected family members, and variants in another known or candidate HL gene were detected to clarify HL in the entire family. We also present a variant in TOGARAM2 as a potential cause underlying autosomal recessive non-syndromic HL by showing its presence in a family with HL, its expression in the cochlea and the localization of the protein to cochlear hair cells. Conclusively, analyzing all affected family members separately can serve as a good source for the identification of variants in known and novel candidate genes for HL.

Novel GPR156 variants confirm its role in moderate sensorineural hearing loss.

Hereditary hearing loss (HL) is a genetically heterogeneous disorder affecting people worldwide. The implementation of advanced sequencing technologies has significantly contributed to the identification of novel genes involved in HL. In this study, probands of two Turkish families with non-syndromic moderate HL were subjected to exome sequencing. The data analysis identified the c.600G > A (p.Thr200Thr) and c.1863dupG (p.His622fs) variants in GPR156, which co-segregated with the phenotype as an autosomal recessive trait in the respective families. The in silico predictions and a minigene assay showed that the c.600G > A variant disrupts mRNA splicing. This gene belongs to the family of G protein-coupled receptors whose function is not well established in the inner ear. GPR156 variants have very recently been reported to cause HL in three families. Our study from a different ethnic background confirms GPR156 as a bona fide gene involved in HL in humans. Further investigation towards the understanding of the role of GPCRs in the inner ear is warranted.

Cadmium-induced hepatotoxicity and its abrogation by thymoquinone.

Cadmium (Cd(2+) ) causes alteration of the cellular homeostasis and oxidative damage. The aim of the present study was to investigate the possible protective role of thymoquinone (TQ), a predominant bioactive component present in black seed oil (Nigella sativa) on the hepatotoxicity of Cd(2+) with special reference to its protection against perturbation of nonenzymatic and enzymatic antioxidants. The effect of TQ pretreatment was examined in postnuclear supernatant prepared from liver of Swiss albino mice under in vitro conditions. CdCl(2) treatment (5 mM) resulted in a significant increase in antioxidant enzymatic activities. It also caused a significant (p < 0.001) increase in protein carbonyl and reduced glutathione content. Pretreatment with TQ (10 µM) showed a significant protection as manifested by noticed attenuation of protein oxidation and rejuvenation of the depleted antioxidants of cellular fraction. These results strengthen the hypothesis that TQ exerts modulatory influence on the antioxidant defense system on being subjected to toxic insult.

Perillyl alcohol alleviates amyloid-ß peptides-induced mitochondrial dysfunction and cytotoxicity in SH-SY5Y cells.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia in elderly ( >65years of age). Excessive extra cellular deposits of amyloid beta (Aß) are a pathological feature of AD. Aß can cause cell death through oxidative damage; recent studies have implicated opening of mPTP as a detrimental event in AD-related mitochondrial dysfunctions. Over the past few years, natural compounds with antioxidant properties have shown promise for intervention in AD.

In vivo induction of antioxidant response and oxidative stress associated with genotoxicity and histopathological alteration in two commercial fish species due to heavy metals exposure in northern India (Kali) river.

Heavy metals can significantly bioaccumulate in fish tissues. The step wise mechanism of heavy metal toxicities on fish health is still limited. The present study assessed the tissue-specific antioxidant response and oxidative stress biomarkers of commercially important fish species namely, Channa striatus and Heteropneustes fossilis inhabiting Kali River of northern India where heavy-metal load is beyond the World Health Organisation - maximum permissible limits. Heavy metals chromium (Cr), nickel (Ni), lead (Pb) and cadmium (Cd) were elevated in both fish species compared to recommended values of the Federal Environmental Protection Agency (FEPA), 1999 for edible fishes. Reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CATA) activities in all tissues (brachial, neural, renal and hepatic) were altered. Cellular lipid and protein compromisation in both fishes induced by heavy metals was determined by lipid peroxidation (LPO) and protein carbonylation (PC) assays. Micronucleus (MN) test of erythrocytes and comet assay of liver cells confirmed genotoxicity. Histopathology of the liver, kidney and brain of affected fishes was distorted significantly with its reference fishes thereby affecting the quality and quantity of these fish stocks. This raises a serious concern as these fishes are consumed by the local population which would ultimately affect human health.