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PubMed1984

Biochemical and genetic analysis of variant mouse hepatoma cells which overtranscribe the cytochrome P1-450 gene in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Using the fluorescence-activated cell sorter, we have isolated a population of variant mouse hepatoma cells which have a markedly increased ability to metabolize benzo(a)pyrene. Compared with wild-type (Hepa 1c1c7) cells, the variant cells exhibit increased aryl hydrocarbon hydroxylase activity and increased responsiveness of the aryl hydrocarbon hydroxylase induction mechanism to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Cell fusion experiments indicate that the variant phenotype is co-dominant with respect to wild-type. Filter hybridization analyses indicate that increased accumulation of cytochrome P1-450-specific mRNA accounts for the overproduction of aryl hydrocarbon hydroxylase activity. Measurements of RNA synthesis in isolated nuclei reveal that the variants exhibit an increased rate of transcription of the cytochrome P1-450 gene in response to TCDD. The variant cells contain no detectable alteration in their TCDD receptors, nor is the cytochrome P1-450 gene amplified in the variants. Filter hybridization analyses of restriction endonuclease-digested DNA indicate that the variant cytochrome P1-450 gene is relatively undermethylated, compared with the wild-type gene. We conclude that the variant cells contain an altered cis-acting genomic element(s) which regulates the expression of the cytochrome P1-450 gene.

Animals↗

PubMed1983

Creatine kinase variants. Report on the workshop conference of the German Society for Clinical Chemistry held on September 19 to 21, 1982 in Tübingen, FRG.

It was the aim of the workshop to summarize present knowledge of the variant creatine kinases in human blood. Discussion was centered on the nature, measurement, and clinical significance of these variants. On the basis of the presented results, the different creatine kinase variants can be classified as follows: Normal size variants (80000 Daltons). These originate from postsynthetic modifications of the three dimeric isoenzymes creatine kinase-MM, MB or BB. The M subunit can be transformed by a serum constituent and these modifications result in at least three different creatine kinase-MM and two creatine kinase-MB variants, which still show catalytic activity. The mechanism of the postsynthetic alterations of creatine kinase-BB seems to be more complex: In vitro incubation of this isoenzyme even in a non-serum matrix changes its electrophoretic mobility and decreases activity. In vivo there is evidence that on the one hand intact creatine kinase-BB molecules are directly removed from the circulation. On the other hand, however, inactive creatine kinase-BB-protein is reported to occur in serum. Variants with higher molecular weights (greater than 200000 Daltons). These are termed macro creatine kinases. Macro creatine kinase type 1 comprises the immunoglobulin-bound creatine kinase isoenzymes. Of these immune complexes, IgG-linked creatine kinase-BB is well known and has been described in detail, whereas the occurrence of creatine kinase-MM-containing macro creatine kinases is still questionable. Macro creatine kinase type 1 is found in the blood of about 2% of all hospitalized patients. It occurs mainly in elderly women, but it is not known whether it has any special clinical significance. Macro creatine kinase type 2 is the term for an oligomeric form of mitochondrial creatine kinase released after breakdown of mitochondria in liver, heart and some tumours. After treatment with urea this oligomeric form is converted into a normal sized, dimeric creatine kinase-MiMi. Macro creatine kinase type 2 is found exclusively in seriously ill patients, and may occur in more than 3% of all hospitalized patients. This classification of the creatine kinase variants seems logical, since it takes into account the nature of the creatine kinase variants, and it permits the classification of all atypical creatine kinases described in the literature. As quantification and differentiation now become possible, further experimental and clinical investigations should provide the information necessary for a better understanding of the physiology and pathobiochemistry of these multiple forms of creatine kinase.

Creatine Kinase↗

PubMed1982

ACP1GUA-1--a low-activity variant of human erythrocyte acid phosphatase: association with increased glutathione reductase activity.

ACP1GUA-1, a variant of human erythrocyte acid phosphatase, exists as a polymorphism (allele frequency of .132) in the Guaymi Indians of Central America. This variant has an electrophoretic mobility similar to the common B- and C-type variants, but individuals of the ACP1GUA-1 phenotype have a level of enzyme activity only 27% of the activity expected for the ACP1C variant. The GUA-1 variant is more thermostable than is the B variant, and the order of responsiveness to the modulation of activity by purine analogs and folate is always (B)-(A)-(GUA-1). Thus, the GUA-1 variant is a low-activity variant with C-like regulatory properties. Erythrocytes from individuals of the ACP1GUA-1 phenotype have increased basal levels of glutathione reductase, and a larger fraction of the glutathione reductase protein is present as the holoenzyme, indicating increased levels of flavin adenine dinucleotide in the erythrocytes of these individuals. This is consistent with the suggestion that ACP1 has a physiological function as a flavin mononucleotide phosphatase.

Acid Phosphatase↗

PubMed1982

Comparative analysis of procedures used to isolate variant antigen from Trypanosoma brucei rhodesiense.

Comparisons made among various procedures leading to the isolation of variant antigen from Trypanosoma brucei rhodesiense bloodstream trypomastigotes. As a means of parasite disruption, freeze-thawing solubilized 36% more variant antigen than did sonication. Protease inhibitors were important additions to the suspension prior to cellular disruption. If trypanosomal extracts were frozen for at least 1 wk prior to chromatographic isolation of variant antigen, recovery of the antigen was reduced by 70%. Ion exchange chromatography was more efficient in the isolation of variant antigen than either lentil-lectin or antibody-affinity columns. All three methods yielded qualitatively similar variant antigen preparations. Using the most efficient isolation procedure tested, about 4 mg of variant antigen was isolated per 10(10) bloodstream trypomastigotes. The most efficient means of isolating variant antigen from plasma of infected rats began with passage of fresh plasma with protease inhibitors through an ion exchange column followed by antibody-affinity chromatography. This resulted in a preparation that was 52% variant antigen, a 370-fold concentration over plasma levels.

Animals↗

PubMed1994

Recombinant variants of tissue-type plasminogen activator containing amino acid substitutions in the fibronectin finger-like domain and the kringle 1 domain.

Tissue-type plasminogen activator (t-PA) is a fibrin-specific agent which is used to treat acute myocardial infarction. Pharmacokinetically, t-PA is characterized by a rapid clearance from the circulation. In a previous study, we constructed variant forms of t-PA with genetic modifications at the fibronectin finger-like domain (finger domain) or at the kringle 1 domain (K1 domain). The finger modified variant, t-PA N37S.S38V.G39V.R40E. A41F.Q42S had about a 6.0-fold higher plasma half-life in vivo than wild-type t-PA. Two variants with modifications in the K1 domain, t-PA G161R.K162R.S165W and t-PA N115P, showed an improved kinetic parameters and a 2.2-fold higher plasma half-life in vivo than wild-type t-PA, respectively. To create a recombinant variant of t-PA with a higher enzymatic activity and a further prolonged half-life in vivo, the genes containing each modifications were joined and expressed in animal cells. The two variants, t-PA N37S.S38V.G39V.R40E.A41F.Q42S.G16 1R.K162R.S165W and t-PA N37S.S38V.G39V.R40E.A41F.Q42S.N11 5P, were purified from conditioned media and their biochemical, pharmacokinetic and thrombolytic profiles were investigated. Although the variant t-PA N37S.S38V.G39V.R40E.A41F.Q42S.G16 1R.K162R.S165W demonstrated an impaired enzymatic activity compared to the wild-type t-PA, the half-life of the variant, t-PA N37S.S38V.G39V.R40E.A41F.Q42S. N115P, following intravenous bolus injection in rabbits was considerably longer than that of finger-domain modified variants.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1996

Hyaluronate-independent metastatic behavior of CD44 variant-expressing pancreatic carcinoma cells.

Several studies have demonstrated a correlation between the expression of CD44 variant isoforms and the ability of tumor cells to metastasize. The CD44 proteins carry amino acid sequence motifs that confer the ability to bind to the extracellular matrix component hyaluronate (HA). In this study, we investigated whether a CD44 variant previously shown to stimulate metastasis in a rat pancreatic carcinoma model (BSp73AS) is capable of binding to HA, and whether such binding is critical for metastasis. We show that transfection of this CD44 variant into BSp73AS cells increases the HA-binding capacity of the cells in a dose-dependent manner. Transfection of the same CD44 variant isoform into BDX2 cells also conferred strong HA-binding properties on these cells, but was insufficient to cause them to metastasize. Transfection of a surface-bound hyaluronidase into metastasizing BSp73AS cells bearing variant CD44 efficiently ablated the ability of these cells to bind to HA. However, in metastasis assays, these hyaluronidase-transfected cells showed patterns of metastasis similar to those of the parental cell line. We also show that the HA-binding capacity of a variety of tumor cells is not correlated with their metastatic proclivity, and that an antibody previously shown to block metastasis of the pancreatic carcinoma cells does not interfere with their ability to bind to HA. We conclude that although CD44 variant expression does promote metastasis formation, HA binding by tumor cells is not rate limiting for metastasis in the BSp73AS system and probably also in other metastasizing tumors. Furthermore, for metastasis by CD44 variant-expressing BSp73AS cells to occur, contact of the CD44 variant protein with a ligand other than HA Is required.

Amino Acid Sequence↗

PubMedDate not supplied

Evaluation of a commercial modified live virus fowl pox vaccine for the control of "variant" fowl poxvirus infections.

Three-week-old specific-pathogen-free chickens were vaccinated with either a commercial modified live virus fowl pox vaccine or five "variant" poxvirus field isolates. Immunity engendered by the commercial modified vaccine or field isolates was challenged with either the variant isolates or commercial modified vaccine virus. The commercial modified vaccine did not adequately protect vaccinates against challenge with the variant isolates. The percentages of vaccinated chickens protected following challenge with each of the variant isolates were 70%, 20%, 30%, 20%, and 25%. However, when the isolates were applied as vaccines, 100% of the vaccinates were protected against challenge from the modified vaccine virus. Furthermore, the variant poxvirus isolates offered excellent protection from challenge with homologous variant isolates. The modified live virus vaccine was expected to offer significant protection against challenge from the variant pox isolates, but in this experiment it did not. The variant isolates tested may be good vaccine candidates to prevent the vaccine breaks currently encountered in previously pox-vaccinated flocks.

Animals↗

PubMed1997

Expression of estrogen receptor variant messenger RNAs and determination of estrogen receptor status in human breast cancer.

Estrogen receptor (ER) status of breast cancer can be assessed by immunohistochemical assay (IHA), although we have previously observed that ER-IHA levels can be inconsistent between amino-terminal and carboxyl-terminal-targeted antibodies. To address the hypothesis that this discrepancy is attributable to expression of ER variant mRNAs encoding truncated ER-like proteins, we have studied 39 IHA-consistent and 24 IHA-inconsistent breast tumors by reverse transcription polymerase chain reaction to examine the expression of multiple exon-deleted (D-ER) variant mRNAs and the truncated ER clone 4 variant mRNA. ER variants D7-ER, D-3-4-ER, and D4-7-ER were detected at similar frequencies in both groups. However, ER variants D2-3/7-ER, D2-3-4-ER (P < 0.05), and D-3-7-ER (P < 0.01), which encode putative short ER-like proteins that might be recognized only by an amino-terminal-targeted antibody, were preferentially detected in inconsistent cases. ER clone 4 mRNA expression was also higher in inconsistent tumors (P < 0.001). Further analysis showed that, whereas overall prevalence of ER variant mRNAs was similar in both tumor groups, occurrence of the subset of variant mRNAs encoding putative truncated proteins was also higher in IHA-inconsistent tumors (P < 0.05). These data suggest that ER variant mRNAs encoding truncated ER proteins may contribute to discrepancies in ER-IHA levels determined using amino- or carboxyl-terminal-targeted antibodies.

Breast Neoplasms↗

PubMed1979

[Role of gramicidin S in the sporulation of the R+ and R- variants of Bacillus brevis var. G.-B].

The effect of gramicidin S added to the cultivation medium on sporulation of the gramicidin S-producing P+ variant and gramicidin S-nonproducing P- variant of Bacillus brevis var. G.-B. was studied. Gramicidin S added to the synthetic medium with glucose in an amount of 30 and 100 microgram/ml 4 and 7 hours after inoculation with the vegetative cells of R- variant had no effect on the growth of the culture but retarded its sporulation. When gramicidin S was added in an amount of 100 microgram/ml 4 hours after inoculation, the sporulation rate of R- variant strongly decreased, rohile sporulation was not suppressed as it was noted before with respect to R+ variant. Active stimulation of Bacillus brevis var. G.-B. sporulation was observed after addition of gramicidin S 13 hours after development of R+ and R- variants without the antibiotic biosynthesis. Synthesis of gramicidin S by R+ strain was suppressed by the specific inhibitor beta-phenyl-beta-alanine. The amount of gramicidin S added to the medium during the sporulation process of R+ and R- variants decreased. On addition of 30 microgram/ml of the antibiotic it was practically not detectable when the culture showed the greatest number of the spores. Therefore, gramicidin S added to the medium is probably adsorbed by the cells of Bac. brevis var. G.-B. and affects sporulation of R- and R+ variants thus accelerating or retarding this process depending on the cultivation conditions.

Bacillus↗

PubMed1997

[Molecular characterization of two variants of alpha-1-antitrypsin deficiency: PI Mpalermo and PI Plovel].

BACKGROUND: Alpha 1 antitrypsin (AAT) is a highly polymorphic protein, having more than 75 different variants. In this work two rare AAT deficient variants were characterized by DNA study. PATIENTS AND METHODS: Members of three generations of two separate families were studied. In family 1, the index case was affected with pulmonary emphysema and presented AAT deficiency (23 mg/dl). In family 2, the index case had a normal pulmonary function, an AAT serum level of 72 mg/dl and a phenotype heterozygous for an AAT variant migrating in the P variant region. The AAT variants were characterized by polymerase chain reaction amplification of the coding exons and direct sequencing of the amplification products. RESULTS: Direct DNA sequencing from a member of family 1 demonstrates that in the exon II of the normal M1 (Val213) allele there was a 3-bp deletion (TTC), corresponding to Phe51 or Phe52. This mutation is characteristic of the Pl Mpalermo variant. In our study, Pl Mpalermo was detected in six members of three generations of this same family. Sequencing of exon III in a member of family 2, identified in the common M1 (Val213) allele a single base substitution of GAT-GTT, with the resulting amino acid change Asp256 for Val256. This mutation characterizes the Pl Plovel allele. The Pl Plovel was also detected in nine members of five others independent families. All of them have AAT serum levels between 80 and 102 mg/dl. None of the studied subjects had clinical evidence of lung disease. CONCLUSIONS: The results of our study show the presence of the two AAT deficient variants in Spain and suggest that the Pl Plovel variant might be more common than expected.

Adult↗

PubMed1997

Expression of tenascin-C by human endometrial adenocarcinoma and stroma cells: heterogeneity of splice variants and induction by TGF-beta.

Localization of tenascin-C in vivo and cell culture experiments in vitro have provided evidence for stromal production of tenascin-C in malignant tumors of a variety of organs. Here we raised the question of whether the mesenchymal stroma in the case of endometrial adenocarcinoma is the unique source of tenascin-C. Therefore, the expression of tenascin-C mRNA by human endometrial adenocarcinoma cells and endometrial stroma cells was investigated. Several preparations of endometrial stroma cells produced tenascin-C mRNA. Using a serum-free defined cell culture medium, production of tenascin-C mRNA could be increased by adding either serum or 20 ng TGF-beta/mL to the cell culture medium. Reverse transcriptase polymerase chain reaction analysis revealed that five out of six endometrial adenocarcinoma cell lines produced tenascin-C mRNA. Northern blot experiments and ribonuclease protection assays provided evidence that the number of copies of tenascin-C mRNA was small. Analysis of expressed splice variants by reverse transcriptase polymerase chain reaction analysis revealed the abundance of one major splice variant that lacked all potential alternatively spliced fibronectin type-III-like repeats. Regarding larger splice variants, all fragment sizes that could theoretically originate from seven alternatively spliced fibronectin type-III-like repeats were observed. Evaluating relative signal intensities, the splice variants containing a single fibronectin type-III-like repeat and the variant possessing all but one alternatively spliced repeats were most frequent. In summary, evidence is provided that tenascin-C can originate from both tissue compartments of the human endometrium stroma and (tumor) epithelium. Splice variant analysis revealed a high number of splice variants and a relative high proportion of variants that have so far been regarded as minor constituents of expressed tenascin-C.

Adenocarcinoma↗

PubMed1998

Differences in susceptibility to tumor necrosis factor alpha-induced apoptosis among MCF-7 breast cancer cell variants.

Widespread use of MCF-7 human breast carcinoma cells as a model system for breast cancer has led to variations in these cells between different laboratories. Although several reports have addressed these differences in terms of proliferation and estrogenic response, variations in sensitivity to apoptosis have not yet been described. Tumor necrosis factor alpha (TNF-alpha) has been shown to both induce apoptosis and inhibit proliferation in MCF-7 cells. We observed that TNF-alpha inhibited proliferation in MCF-7 cell variants from three different laboratories (designated M, L, and N). MCF-7 M cells were resistant to TNF-alpha-induced apoptosis, whereas MCF-7 L cells were moderately resistant to the effect of TNF-alpha. A third variant, MCF-7 N, underwent apoptosis when exposed to TNF-alpha. Analysis of the p55 TNF-alpha receptor (TNFR) 1 expression revealed the greatest expression in MCF-7 N cells, whereas the MCF-7 L and M cells expressed 89 and 67% of MCF-7 N cell TNFR1 levels, respectively. Ceramide generation occurred in all three variants in response to TNF-alpha treatment, with MCF-7 N cells expressing the greatest increase. Cleavage of the CPP32/caspase 3 substrate poly(ADP-ribose) was observed in MCF-7 N and L cells as early as 3 and 6 h, respectively, but poly(ADP-ribose) cleavage was not observed in MCF-7 M cells. The delayed protease activation in the L variant may represent the mechanism by which these cells display delayed sensitivity to TNF-a-induced apoptosis. Expression of the Bcl-2, Mcl-1, Bcl-X, Bax, and Bak proteins was analyzed to determine whether the differences in MCF-7 cell sensitivity to apoptosis could be correlated to the differential expression of these proteins. Whereas Bak, Bcl-X, and Mcl-1 levels were identical between variants, the levels of Bcl-2 were 3.5-3.8-fold higher and the levels of Bax were 1.5-1.7-fold lower in the resistant variants (M and L) as compared with those of the sensitive variant (N). Taken together, these results suggest that differences in susceptibility to TNF-alpha-induced apoptosis among MCF-7 breast cancer cell variants may be explained by differences in TNFR expression, ceramide generation, differential expression of the Bcl-2 family of proteins, and protease activation.

Apoptosis↗

PubMed2025

Phenotypic pleiotropy of missense variants in human B cell confinement receptor P2RY8.

Missense variants can have pleiotropic effects on protein function, and predicting these effects can be difficult. We performed near-saturation deep mutational scanning of P2RY8, a G protein-coupled receptor that promotes germinal center B cell confinement. We assayed the effect of each variant on surface expression, migration, and proliferation. We delineated variants that affected both expression and function, affected function independently of expression, and discrepantly affected migration and proliferation. We also used cryo-electron microscopy to determine the structure of activated, ligand-bound P2RY8, providing structural insights into the effects of variants on ligand binding and signal transmission. We applied the deep mutational scanning results to both improve computational variant effect predictions and to characterize the phenotype of germline variants and lymphoma-associated variants. Together, our results demonstrate the power of integrating deep mutational scanning, structure determination, and in silico prediction to advance the understanding of a receptor important in human health.

Humans↗

PubMed2026

Somatic-only SDHD variant with tumor-specific loss of heterozygosity in metastatic carotid body tumor: a case report with review of literature.

Carotid body tumors (CBTs) are rare paragangliomas in which genetic predisposition, particularly pathogenic variants in succinate dehydrogenase (SDHx) genes, plays an important role in tumorigenesis. Previous genetic studies of CBTs have primarily focused on germline SDHx variants, whereas somatic alterations remain poorly characterized. Among SDHx genes, SDHB variants are known to be associated with a higher metastatic risk, while SDHD variants are generally linked to a lower metastatic rate. We report the case of a 41-year-old man who presented with a painless right-sided neck mass. Imaging studies demonstrated a hypervascular tumor located at the carotid bifurcation with circumferential encasement of the carotid artery. During surgery, the tumor was classified as a Shamblin type III CBT, and complete surgical resection with vascular reconstruction was performed. Histopathological examination confirmed paraganglioma with metastasis to a single cervical lymph node. Germline genetic testing did not reveal any pathogenic variants. However, comprehensive tumor genomic profiling identified a somatic SDHD c.304C>G (p.His102Asp) variant accompanied by tumor-specific loss of heterozygosity (LOH) and copy-number loss at the SDHD locus, findings compatible with biallelic SDHD inactivation. The patient remained free of recurrence during follow-up. To our knowledge, this represents the first reported case of metastatic CBT harboring a somatic-only SDHD variant with tumor-specific LOH. This case suggests that reliance on germline testing alone may underestimate the molecular drivers of CBT and highlights the potential clinical value of tumor-based genomic profiling for risk stratification and prognostic assessment.

Carotid body tumor↗

PubMed2026

Deep DNA and protein level feature integration for robust clinical variant interpretation using probabilistic gradient boosting.

A major challenge in clinical genomics is to classify genetic variations correctly, since it directly affects disease diagnosis and personal care. The existing methods tend to be based on the combination of different factors, such as protein structure, population frequencies, phenotypic annotations, and sequence conservation. Nevertheless, these methods often cannot be used to achieve the necessary interpretability, quantify uncertainty, and address rare cases. This paper presents a probabilistic gradient boosting model on variant pathogenicity prediction. The suggested framework applies biological characteristics at both level of DNA and protein levels while also scaling the level of uncertainty in clinical decision making. Our machine learning aims to solve the issues of variant interpretation by managing the features and through probability-based pathogenicity prediction. The framework formulation is aimed at generalizing over various datasets and minimizing overfitting. At the same time, it can ensure reasonable performance to facilitate clinical experiments. The model has also been tested on three standard datasets and demonstrated to be more predictive of the pathogenic effect of variants, in comparison with a variety of existing tools. The probabilistic gradient boosting model proposed had ROC AUC values of 0.9293, 0.9610, and 0.9646 on ClinVar variants, GRCh37, and GRCh38 human genome respectively. Furthermore, the dataset was ensured to include both exonic and intronic variants, and Variants of Uncertain Significance were also taken into consideration for Performance Testing. Through this it also aims to provide better clinical significance which will lead to a good interpretable tool for priority of variants for a large variety of disease conditions.

ClinVar↗

PubMed1983

Genomic organization of variant surface glycoprotein genes in Trypanosoma brucei procyclic culture forms.

The production of the variant surface glycoprotein coat of bloodstream form African trypanosomes ceases after conversion to the procyclic form. In the bloodstream stage alternate expression of different variant surface glycoprotein genes is responsible for the antigenic variation that occurs during relapse infections in the mammalian host. We have examined procyclic stage populations, derived from different bloodstream variant antigen types, for the two types of genomic alterations associated with variant surface glycoprotein genes in the bloodstream stage. Transcriptional activation of some variant antigen genes is accompanied by the generation of a new copy of the gene, the expression-linked copy. We find that the expression-linked copy is maintained after conversion to procyclic form, indicating that the presence of an expression-linked copy is not sufficient for the expression of a surface coat. Sequences 3' to other variant surface glycoprotein genes show expression-independent variation in bloodstream stage trypanosomes. The same genes showed variation between procyclic populations of different origin, and between procyclics and their bloodstream parent. These data are discussed in light of observations on the sequence of variant antigen expression after cyclic transmission.

Animals↗

PubMed2026

Investigating genetic susceptibility to concussion through rare variants in ion channel and neurotransmission genes.

Some individuals appear more susceptible to concussion or mild traumatic brain injury (mTBI) and the severity, range, and the persistence of post-concussion symptoms vary considerably between affected individuals. Genetic factors are likely to contribute to this variability. Symptomatic overlap of post-concussion syndrome with neurological conditions such as familial hemiplegic migraine (FHM) caused by rare pathogenic variants in ion channel and synapse protein genes, with high sensitivity to head trauma for some patients, suggests that variation in similar pathways may influence concussion susceptibility and recovery. To investigate this hypothesis, we performed whole exome sequencing in 93 unrelated individuals who had sustained a single or multiple concussions and examined rare protein-altering variants in FHM genes, other neuronal ion channel and transporter genes, and genes involved in neurotransmission. We identified 62 different rare missense variants across 24 genes in 59 participants (63%), with 26 individuals carrying 2 or more variants. The prevalence of specific likely damaging rare variants in the 16 ion channel-related genes that were identified was approximately fivefold higher than that observed from gnomAD population controls (Odds Ratio = 5.44, 95% CI [4.13,7.18], P < 0.0001). Notably, voltage-gated calcium and sodium channel genes, including SCN9A, together with neurotransmission-related genes such as SNCAIP, harboured multiple potentially deleterious variants. These findings suggest that rare deleterious variants in genes involved in ion homeostasis and neurotransmission may contribute to an individual's susceptibility to concussion or more severe post-concussion symptoms. This study provides a foundation for future genetic and functional investigations aimed at improving our understanding of concussion susceptibility and outcomes. Further validation in larger cohorts and mechanistic studies is warranted to determine their utility as biomarkers of concussion risk and prognosis.

Humans↗

PubMed2026

A novel variant combination in COASY associates with severe prenatal onset PCH12: expanding the clinical and genetic spectrum.

Pontocerebellar hypoplasia type 12 (PCH12) is an ultra-rare, perinatal lethal, neurodegenerative disorder with microcephaly and arthrogryposis. Previous reports have associated PCH12 with complete loss-of-function variants in COASY identified in 14 fetuses and newborns from eight unrelated families. In contrast, COASY partial loss-of-function variants have been linked to COASY protein-associated neurodegeneration (CoPAN), a subtype of neurodegeneration with brain iron accumulation (NBIA). Emerging evidence suggests that COASY-related disorders may represent a phenotypic continuum between PCH12 and CoPAN. Using exome sequencing, we identified a previously reported missense variant (c.641C>T, p.Ala214Val) as well as a previously unreported rare nonsense variant (c.1015C>T, p.Arg339*) in a compound heterozygous state in the COASY gene in a patient presenting with clinical features consistent with PCH12. The p.Ala214Val variant has only been described in combination with another missense variant (p.Arg499Cys) in two siblings with CoPAN. The presence of p.Ala214Val in trans with the truncating p.Arg339* variant in this patient is associated with a severe perinatal lethal phenotype resembling PCH12. This case broadens the reported genetic and phenotypic spectrum of COASY-associated disorders and highlights the importance of continued genotype-phenotype correlation investigation.

Humans↗