Characterization and applications of glutaminase free L-asparaginase from indigenous Bacillus halotolerans ASN9.

L-asparaginase (L-ASNase) is a versatile anticancer and acrylamide reduction enzyme predominantly used in medical and food industries. However, the high specificity of L-asparaginase formulations for glutamine, low thermostability, and blood clearance are the major disadvantages. Present study describes production, characterization, and applications of glutaminase free extracellular L-asparaginase from indigenous Bacillus halotolerans ASN9 isolated from soil sample. L-asparaginase production was optimized in M9 medium (containing 0.2% sucrose and 1% L-asparagine) that yielded maximum L-ASNase with a specific activity of 256 U mg-1 at pH 6 and 37°C. L-asparaginase was purified through acetone precipitation and Sephadex G-100 column, yielding 48.9 and 24% recovery, respectively. Enzyme kinetics revealed a Vmax of 466 mM min-1 and Km of 0.097 mM. Purified L-ASNase showed no activity against glutamine. The purified glutaminase free L-ASNase has a molecular mass of 60 kDa and an optimum specific activity of 3083 U mg-1 at pH 7 and 37°C. The enzyme retains its activity and stability over a wide range of pH and temperature, in the presence of selected protein inhibitors (SDS, ß-mercaptoethanol), CoCl2, KCl, and NaCl. The enzyme also exhibited antioxidant activity against DPPH radical (IC50 value 70.7 µg mL-1) and anticancer activity against U87 human malignant glioma (IC50 55 µg mL-1) and Huh7 human hepatocellular carcinoma (IC50 37 µg mL-1) cell lines. Normal human embryonic kidney cells (HEK293) had greater than 80% cell viability with purified L-ASNase indicating its least cytotoxicity against normal cells. The present work identified potent glutaminase free L-ASNase from B. halotolerans ASN9 that performs well in a wide range of environmental conditions indicating its suitability for various commercial applications.

Antioxidants and Calcium Modulators Preclude in Vitro Hepatitis B Virus-Induced Mitochondrial Damage.

BACKGROUND/AIMS: Hepatitis B virus induces mitochondrial damage via the production of reactive oxygen species and concomitant with deregulation of calcium homeostasis. The current study evaluates the potential of antioxidant and calcium modulators for inhibition of hepatitis B virus-induced mitochondrial damage using in vitro cell culture models. MATERIALS AND METHODS: Hepatitis B virus-induced mitochondrial fragmentation was observed by immunofluorescence confocal micros- copy in hepatitis B virus-infected cell lines (HepG2 and HepAD38). Differential protein expression of mitochondrial fragmentation mark- ers, dynamin-related protein 1 and phospho-dynamin-related protein 1, were evaluated both pre- and posttreatment with antioxidant N-acetyl-l-cysteine and calcium modulators like 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakisacetoxymethyl ester, ethylene-bis (oxyethylenenitrilo) tetraacetic acid glycol ether diamine tetraacetic acid-acetoxymethyl ester, and ruthenium amine complex by western blot analysis. RESULTS: A slight reduction in mitochondrial fragmentation in both cell lines was observed post-antioxidant treatment with a partial prevention observed with calcium modulators. The expression of phospho-dynamin-related protein 1 was significantly upregulated (P = .0007, P = .003) in both hepatitis B virus-infected cell lines compared to uninfected cells. In line with these observations, the expres- sion of dynamin-related protein 1 and phospho-dynamin-related protein 1 was found to be significantly downregulated with N-acetyl- l-cysteine treatment in both cell lines (P = .003, P = .002), respectively. A nonsignificant trend was observed in the case of calcium modulators treatment. CONCLUSIONS: Current study indicates that the mitochondrial fragmentation induced by hepatitis B virus infection can be reduced after antioxidant treatment pointing toward exploring better drug targets for the prevention of hepatitis B virus-induced mitochondrial frag- mentation and associated liver damage.

Structural and functional insights into a novel homozygous missense pathogenic variant in CUL7 identified in consanguineous Pakistani family.

3M syndrome is a rare genetic familial disorder characterized by short stature, growth retardation, facial dysmorphism, skeletal abnormalities, fleshy protruding heels, and normal intelligence, caused by mutations in the CUL7, OBSL1 and CCDC8 genes. In the present study, a novel homozygous missense variant of CUL7 (NP_001161842.1, c.4493T > C, p.L1498P) has been identified in a consanguineous Pakistani family by whole exome sequencing. In silico structural evaluation, molecular docking and simulation studies of mutant CUL7 provides substantial evidence about its crucial role in the progression of discussed ailment. The newly discovered variant significantly altered the protein's three dimensional structure, leading to abnormal interaction with binding proteins. This computational and experimental investigation provides useful information to drug developers for the synthesis of novel therapeutics against the discussed ailment.Communicated by Ramaswamy H. Sarma.

Restoration of IL-11 and IL-15 cytokine production post calcium modulators and ROS treatment can assist viral clearance both in vitro and in vivo.

Objectives: Hepatitis B virus (HBV) infection alters the cytokines production to establish persistent infection. A reversion of cytokines back to their normal state can be a promising therapeutic approach to establish an optimal host immune response. Materials and Methods: We investigated the alteration in expression of IL-15 and IL-11 after HBV infection in vitro and in vivo in PBMCs of 63 individuals divided into various HBV-infected patient groups. The mRNA expression was evaluated post-anti-oxidant and calcium modulators treatment by Real-time qPCR. Results: In vitro mRNA expression of both cytokines, post-infection was down-regulated considerably. Interestingly, in line with in vitro results, both cytokines' in vivo expression was intensively down-regulated in chronic HBV-infected individuals rather than healthy controls. Both cytokines' expression was up-regulated in cases of recovery compared with the inactive carriers and chronic HBV-infected individuals. IL-15 mRNA expression was significantly up-regulated in both cell lines post EGTA and Ru360 treatment while a significant increase was observed in the HepAD38 cell line with NAC and BAPTA treatment. IL-11 mRNA expression was significantly up-regulated in the HepG2 cell line after all modulator treatments, whereas in the HepAd38 cell line it was observed after BAPTA treatment. Our results thus indicate that viral infection tends to down-regulate the expression of cytokines and an in vivo up-regulation is an indication of recovery. Conclusion: Treatment of anti-oxidants and calcium modulators has resulted in the successful restoration of these cytokines thus pointing towards the use of calcium modulators to boost natural antiviral cytokine production.

An intrafamilial phenotypic variability in Ellis-Van Creveld syndrome due to a novel 27 bps deletion mutation.

Ellis-van Creveld (EvC) syndrome is an autosomal recessive disease, characterized by ectodermal, skeletal, and cardiac anomalies. We report intrafamilial phenotypic variability in three new EvC syndrome cases. Affected males in this study showed only ectodermal abnormalities, whereas an affected female showed the classical presentation of EvC Syndrome, including bilateral postaxial polydactyly of hands and feet, and congenital heart defects. Whole exome sequencing was performed to identify the causative variant, followed by validation and segregation analysis using Sanger sequencing. A homozygous deletion variant (c.731_757del) was identified in exon 6 of the EVC gene (NM_153717.2). The identified variant is considered to be the most likely candidate variant for the EvC syndrome in the family based on previous reports validating the role of EVC variants in the EvC syndrome. The disease correctly segregated in the family members, as all affected members were homozygous, and obligate carriers were heterozygous. Our family is remarkable in highlighting the variable expressivity of the EvC phenotype within the same family, due to a homozygous deletion mutation in the EVC gene. The variable expressivity might be due to the hypomorphic nature of mutation, or the presence of additional variants in modifier genes or in the regulatory regions of the EVC/EVC2 genes.

Effect of oxidative stress and calcium deregulation on FAM26F (CALHM6) expression during hepatitis B virus infection.

BACKGROUND: Family with sequence similarity 26, member F (FAM26F) is an important innate immunity modulator playing a significant role in diverse immune responses, however, the association of FAM26F expression with HBV infection is not yet known. Thus, the current study aims to explore the differential expression of FAM26F in vitro in HepAD38 and HepG2 cell lines upon HBV infection, and in vivo in HBV infected individuals. The effects of antioxidant and calcium inhibitors on the regulation of FAM26F expression were also evaluated. The expression of FAM26F was simultaneously determined with well-established HBV infection markers: IRF3, and IFN-ß. METHODS: The expression of FAM26F and marker genes was analyzed through Real-time qPCR and western blot. RESULTS: Our results indicate that the differential expression of FAM26F followed the same trend as that of IRF3 and IFN-ß. The in vitro study revealed that, in both HBV infected cell lines, FAM26F expression was significantly down-regulated as compared to uninfected control cells. Treatment of cells with N-acetyl-L-cysteine (NAC), EGTA-AM, BAPTA-AM, and Ru360 significantly upregulated the expression of FAM26F in both the cell lines. Moreover, in in vivo study, FAM26F expression was significantly downregulated in all HBV infected groups as compared to controls (p = 0.0007). The expression was higher in the HBV recovered cases, probably due to the decrease in infection and increase in the immunity of these individuals. CONCLUSION: Our study is the first to show the association of FAM26F with HBV infection. It is proposed that FAM26F expression could be an early predictive marker for HBV infection, and thus is worthy of further investigation.

A novel homozygous frameshift mutation in the DCC gene in a Pakistani family with autosomal recessive horizontal gaze palsy with progressive scoliosis-2 with impaired intellectual development.

Horizontal Gaze Palsy with Progressive Scoliosis-2 with Impaired Intellectual Development (HGPPS2) is a rare congenital disorder characterized by absence of conjugate horizontal eye movements, and progressive scoliosis developing in childhood and adolescence. We report three new patients with HGPPS2 in a consanguineous Pakistani family, presenting varying degrees of progressive scoliosis, developmental delays, horizontal gaze palsy, agenesis of corpus callosum, and absence of cerebral commissures. Analysis of genotyping data identified shared loss of heterozygosity (LOH) region on chromosomes 5p15.33-15.31, 6q11.2-12, and 18q21.1-21.3. A hypothesis-free, unbiased exome data analysis detected an insertion of nucleotide A (c.2399dupA) in exon 16 of the DCC gene. The insertion is predicted to cause frameshift p.(Asn800Lysfs*11). Interestingly, DCC gene is present in the LOH region on chromosome 18. Variant (c.2399dupA) in the DCC gene is considered as the most probable candidate variant for HGPPS2 based on the presence of DCC in the LOH region, previously reported role of DCC in HGPPS2, perfect segregation of candidate variant with the disease, prediction of variant pathogenicity, and absence of variant in variation databases. Sanger Sequencing confirmed the presence of the novel homozygous mutation in all three patients; the parents were heterozygous carriers of the mutation, in accordance with an autosomal recessive inheritance pattern. DCC encodes a netrin-1 receptor protein; its role in the development of the CNS has recently been established. Biallelic DCC mutations have previously been shown to cause HGPPS2. A novel homozygous variant in patients of the reported family extend the genotypic and phenotypic spectrum of HGPPS2.

Cost effective and efficient screening of tuberculosis disease with Raman spectroscopy and machine learning algorithms.

The current study presents Raman Spectroscopy (RS) accompanied by machine learning algorithms based on Principle Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) for analysis of tuberculosis (TB). TB positive (diseased), TB negative (cured) and control (healthy) serum samples are considered for inter and intra comparative analysis. Raman spectral differences observed between both TB group and control samples spectra attributed probably to the changes in biomolecules like higher lactate concentration, lowering level of ß-carotene and amide-I band of protein in TB patient's blood samples. Inter comparison between control and TB positive sera samples shows prominent decrease in three extremely intense Raman peaks associated to ß-carotene concentration. Noteworthy spectral differences are also observed among TB positive and TB negative sera samples. The comparison of these Raman results clearly indicate that the blood composition of TB negative patients still showing irregularities in some important elements. Moreover, the Raman spectral differences observed in the data of the control and diseased samples are further highlighted with the help of the machine learning algorithms. In general, a fine correlation has been observed between PCA score plot as well as HCA dendogram with the original Raman findings. Further investigation of such noticeable differences could help in understandings regarding the existing threshold levels. Moreover in future, it can contribute a lot towards the development of new, modified and more effective screening options.

Homozygous variants in the HEXB and MBOAT7 genes underlie neurological diseases in consanguineous families.

BACKGROUND: Neurological disorders are a common cause of morbidity and mortality within Pakistani populations. It is one of the most important challenges in healthcare, with significant life-long socio-economic burden. METHODS: We investigated the cause of disease in three Pakistani families in individuals with unexplained autosomal recessive neurological conditions, using both genome-wide SNP mapping and whole exome sequencing (WES) of affected individuals. RESULTS: We identified a homozygous splice site variant (NM_000521:c.445 + 1G > T) in the hexosaminidase B (HEXB) gene confirming a diagnosis of Sandhoff disease (SD; type II GM2-gangliosidosis), an autosomal recessive lysosomal storage disorder caused by deficiency of hexosaminidases in a single family. In two further unrelated families, we identified a homozygous frameshift variant (NM_024298.3:c.758_778del; p.Glu253_Ala259del) in membrane-bound O-acyltransferase family member 7 (MBOAT7) as the likely cause of disease. MBOAT7 gene variants have recently been identified as a cause of intellectual disability (ID), seizures and autistic features. CONCLUSIONS: We identified two metabolic disorders of lipid biosynthesis within three Pakistani families presenting with undiagnosed neurodevelopmental conditions. These findings enabled an accurate neurological disease diagnosis to be provided for these families, facilitating disease management and genetic counselling within this population. This study consolidates variation within MBOAT7 as a cause of neurodevelopmental disorder, broadens knowledge of the clinical outcomes associated with MBOAT7-related disorder, and confirms the likely presence of a regionally prevalent founder variant (c.758_778del; p.Glu253_Ala259del) in Pakistan.

Plant beneficial endophytic bacteria: Mechanisms, diversity, host range and genetic determinants.

Endophytic bacteria are the plant beneficial bacteria that thrive inside plants and can improve plant growth under normal and challenging conditions. They can benefit host plants directly by improving plant nutrient uptake and by modulating growth and stress related phytohormones. Indirectly, endophytic bacteria can improve plant health by targeting pests and pathogens with antibiotics, hydrolytic enzymes, nutrient limitation, and by priming plant defenses. To confer these benefits, the bacteria have to colonize the plant endosphere after colonizing the rhizosphere. The colonization is achieved using a battery of traits involving motility, attachment, plant-polymer degradation, and evasion of plant defenses. The diversity of endophytic colonizers depends on several bacteria, plant and environment specific factors. Some endophytic bacteria can have a broad host range and can be used as bioinoculants in developing a safe and sustainable agriculture system. This review elaborates the factors affecting diversity of bacterial endophytes, their host specificity and mechanisms of plant growth promotion. The review also accentuates various methods used to study endophytic communities, wild plants as a source of novel endophytic bacteria, and innovative approaches that may improve plant-endophyte association. Moreover, bacterial genes expressed in planta and challenges to study them are also discussed.

Demonstrating the application of Raman spectroscopy together with chemometric technique for screening of asthma disease.

Medical biophotonic tools provide new sources of diagnostic information regarding the state of human health that are used in managing patient care. In our current study, Raman spectroscopy, together with the chemometric technique, has successfully been demonstrated for the screening of asthma disease. Raman spectra of sera samples from asthmatic patients as well as healthy (control) volunteers have been recorded at 532 nm excitation. In healthy sera, three highly reproducible Raman peaks assigned to ß-carotene have been detected. Their sensitive detection is facilitated due to the resonance Raman effect. In contrast, in asthmatic patients sera, the peaks assigned to ß-carotene are either diminished or suppressed accompanied by other new Raman peaks. These new peaks most probably arise due to an elevated level of proteins, which could be used to identify/differentiate between asthma and non-asthma samples. Furthermore, a partial least squares discrimination analysis (PLS-DA) model was developed and applied on the Raman spectra of diseased as well as healthy samples, which successfully classified them. The correlation coefficient (r2) of the model was determined as 0.965. Similarly, the root mean square errors in cross-validation (RMSECV) and in the prediction (RMSECP) are 0.09 and 0.25, respectively. PLS-DA has the potential to be incorporated in a microcontroller's code attached with a hand-held Raman spectrometer for screening purposes in asthma, which is a disease of great concern for the clinicians, especially in children.

CDKN2A/P16INK4A variants association with breast cancer and their in-silico analysis.

CDKN2A was first identified as melanoma predisposition tumour suppressor gene and has been successively studied. The previous researches have not established any noteworthy association with breast cancer. Therefore, through extensive literature search and in-silico analysis, we have tried to focus on the role of CDKN2A in breast cancer. CDKN2A variants in breast cancer were collected from different databases. The overall percentage of variants (approximately 5.8%) and their incidence frequency in breast cancer cases were found to be very low as compared to the number of samples screened in different studies. Exon 2 was identified as the major region of alternations. Approximately 42.8% were entire gene deletions, while 24.2% were missense mutations. These variants cannot be ignored because of their pathogenic effects as interpreted by the bioinformatics tools used in the present study. Earlier studies have shown that CDKN2A excludes the predisposition of germline variants, but interestingly shares common breast cancer germline variants with other carcinomas. Most of the data have revealed this gene as rarely mutated or deleted in breast cancer. However, few association studies have shown that in addition to being a 'multiple' tumour suppressor gene, it is mutated/deleted more in breast cancer cell lines as compared to breast cancer tissues or blood samples; thus, this gene cannot be neglected as a breast cancer candidate gene. The deletion/malfunctioning of CDKN2A in different tumours including breast cancer has recently led to the discovery of many clinical CDK inhibitors. Furthermore, these collected genetic variants will also be helpful in developing diagnostic, preventive, and treatment approaches for patients.

Analysis of tuberculosis disease through Raman spectroscopy and machine learning.

We present the effectiveness of Raman spectroscopy (RS) in combination with machine learning for screening and analysis of blood sera collected from tuberculosis patients. Blood samples of 60 patients have confirmed active pulmonary tuberculosis and 14 samples of healthy age matched control were used in the current study. Spectra from entire sera samples were acquired using 785 nm laser Raman system. Support Vector Machine (SVM) together with Principal Component Analysis (PCA) has been used for highlighting variations spectral intensities between healthy and pathological samples. SVM model using Gaussian radial basis is able to discriminate between healthy and diseased patients based on the differences in the concentration of essential biomolecules such as lactate, ß-carotene, and amide-I. Diagnostic accuracy of 92%, with precision, specificity and sensitivity of 95%, 98% and 81%, respectively, were achieved considering PC3 and PC4. Automatic analysis of the variations in the concentration of these molecules together with chemometrics can effectively be utilized for an early screening of tuberculosis through minimum invasion.

A disease-causing novel missense mutation in the ST14 gene underlies autosomal recessive ichthyosis with hypotrichosis syndrome in a consanguineous family.

Autosomal recessive ichthyosis with hypotrichosis (ARIH; MIM 602400) syndrome is characterized by diffused congenital ichthyosis and generalized non-scarring hypotrichosis. The underlying genetic cause of ARIH syndrome has been associated with sequence variants of the gene ST14, encoding type II transmembrane serine protease matriptase, which maps to chromosome 11q24.3. The current report aimed to investigate the clinical features and genetic cause of ARIH syndrome in a large consanguineous family of Pakistani origin. The technique of homozygosity mapping with highly polymorphic microsatellite markers was employed to establish linkage within the family. Sanger sequencing of exons and intron-exon boundaries of ST14 was performed to identify the potential pathogenic sequence variants, followed by structural analysis of the mutated protein. Linkage was established to chromosome 11q24.3, comprising the gene ST14. Sequence analysis led to the identification of a novel homozygous missense variant (c.1315G>A, p.Gly439Ser) in the ST14 gene that co-segregated with the disease phenotype in all affected members. Homology modelling and molecular docking analysis of ST14 with wild-type TMEFF1 protein was performed which revealed that glycine at position 439 is crucial for maintaining normal structural confirmation and interaction with the EGF domain of TMEFF1 protein. Taken together, the data strongly advocate this ST14 variant as the underlying genetic cause of ARIH syndrome in this first reported affected family from Pakistan. Moreover, the present study adds to the spectrum of mutations in the ST14 gene, implicating them in the pathogenesis of ARIH syndrome.

Exome sequencing revealed a novel nonsense variant in ALX3 gene underlying frontorhiny.

Frontorhiny is one of the two forms of mid-facial malformations characterized by ocular hypertelorism, wide and short nasal ridge, bifid nasal tip, broad columella, widely separated nares, long and wide philtrum and V-shaped hairline. Sometimes these phenotypes are associated with ptosis and midline dermoid cysts. Frontorhiny inherits in an autosomal recessive pattern. Sequence variants in the Aristaless-like homeobox 3 (ALX3) gene underlying frontorhiny have been reported previously. Here, in the present study, we have investigated four patients in a consanguineous family of Pakistani origin segregating frontorhiny in autosomal recessive manner. Genome scan using 250k Nsp1 array followed by exome and Sanger sequence analysis revealed a novel homozygous nonsense variant (c.604C>T, p.Gln202*) in the ALX3 gene resulting in frontorhiny in the family. This is the first mutation in the ALX3 gene, underlying frontorhiny, in Pakistani population.

Sequence variants in nine different genes underlying rare skin disorders in 10 consanguineous families.

BACKGROUND: Genodermatoses represent genetic anomalies of skin tissues including hair follicles, sebaceous glands, eccrine glands, nails, and teeth. Ten consanguineous families segregating various genodermatosis phenotypes were investigated in the present study. METHODS: Homozygosity mapping, exome, and Sanger sequencing were employed to search for the disease-causing variants in the 10 families. RESULTS: Exome sequencing identified seven homozygous sequence variants in different families, including: c.27delT in FERMT1; c.836delA in ABHD5; c.2453C>T in ERCC5; c.5314C>T in COL7A1; c.1630C>T in ALOXE3; c.502C>T in PPOX; and c.10G>T in ALDH3A2. Sanger sequencing revealed three homozygous variants: c.1718 + 2A>G in FERMT1; c.10459A>T in FLG; and c.92delT in the KRT14 genes as the underlying genetic cause of skin phenotypes. CONCLUSION: This study supports the use of exome sequencing as a powerful, efficient tool for identifying genes that underlie rare monogenic skin disorders.

Updated strategies for the management, pathogenesis and molecular genetics of different forms of ichthyosis syndromes with prominent hair abnormalities.

Syndromic ichthyosis is rare inherited disorders of cornification with varied disease complications. This disorder appears in seventeen subtypes associated with severe systematic manifestations along with medical, cosmetic and social problems. Syndromic ichthyosis with prominent hair abnormalities covers five major subtypes: Netherton syndrome, trichothiodystrophy, ichthyosis hypotrichosis syndrome, ichthyosis hypotrichosis sclerosing cholangitis and ichthyosis follicularis atrichia photophobia syndrome. These syndromes mostly prevail in high consanguinity states, with distinctive clinical features. The known pathogenic molecules involved in ichthyosis syndromes with prominent hair abnormalities include SPINK5, ERCC2, ERCC3, GTF2H5, MPLKIP, ST14, CLDN1 and MBTPS2. Despite underlying genetic origin, most of the health professionals solely rely on phenotypic expression of these disorders that leads to improper management of patients, hence making these patients living an orphanage life. After dermal features, association of other systems such as nervous system, skeletal system, hair abnormalities or liver problems may sometimes give clues for diagnosis but still leaving place for molecular screening for efficient diagnosis. In this paper, we have presented a review of ichthyosis syndrome with prominent hair abnormalities, with special emphasis on their updated genetic consequences and disease management. Additionally, we aim to update health professionals about the practice of molecular screening in ichthyosis syndromes for appropriate diagnosis and treatment.

Raman Spectroscopy Combined with Principal Component Analysis for Screening Nasopharyngeal Cancer in Human Blood Sera.

This study demonstrates the analysis of nasopharyngeal cancer (NPC) in human blood sera using Raman spectroscopy combined with the multivariate analysis technique. Blood samples of confirmed NPC patients and healthy individuals have been used in this study. The Raman spectra from all these samples were recorded using 785 nm laser for excitation. Important Raman bands at 760, 800, 815, 834, 855, 1003, 1220-1275, and 1524 cm-1, have been observed in both normal and NPC samples. A decrease in the lipids content, phenylalanine, and ß-carotene, whereas increases in amide III, tyrosine, and tryptophan have been observed in the NPC samples. The two data sets were well separated using principal component analysis (PCA) based on Raman spectral data. The spectral variations between the healthy and cancerous samples have been further highlighted by plotting loading vectors PC1 and PC2, which shows only those spectral regions where the differences are obvious.

Autosomal-Recessive Hearing Impairment Due to Rare Missense Variants within S1PR2.

The sphingosine-1-phosphate receptors (S1PRs) are a well-studied class of transmembrane G protein-coupled sphingolipid receptors that mediate multiple cellular processes. However, S1PRs have not been previously reported to be involved in the genetic etiology of human traits. S1PR2 lies within the autosomal-recessive nonsyndromic hearing impairment (ARNSHI) locus DFNB68 on 19p13.2. From exome sequence data we identified two pathogenic S1PR2 variants, c.323G>C (p.Arg108Pro) and c.419A>G (p.Tyr140Cys). Each of these variants co-segregates with congenital profound hearing impairment in consanguineous Pakistani families with maximum LOD scores of 6.4 for family DEM4154 and 3.3 for family PKDF1400. Neither S1PR2 missense variant was reported among ∼120,000 chromosomes in the Exome Aggregation Consortium database, in 76 unrelated Pakistani exomes, or in 720 Pakistani control chromosomes. Both DNA variants affect highly conserved residues of S1PR2 and are predicted to be damaging by multiple bioinformatics tools. Molecular modeling predicts that these variants affect binding of sphingosine-1-phosphate (p.Arg108Pro) and G protein docking (p.Tyr140Cys). In the previously reported S1pr2(-/-) mice, stria vascularis abnormalities, organ of Corti degeneration, and profound hearing loss were observed. Additionally, hair cell defects were seen in both knockout mice and morphant zebrafish. Family PKDF1400 presents with ARNSHI, which is consistent with the lack of gross malformations in S1pr2(-/-) mice, whereas family DEM4154 has lower limb malformations in addition to hearing loss. Our findings suggest the possibility of developing therapies against hair cell damage (e.g., from ototoxic drugs) through targeted stimulation of S1PR2.