A 50 bp deletion in the SOD1 promoter lowers enzyme expression but is not associated with ALS in Sweden

Variability in SOD1-associated amyotrophic lateral sclerosis: geographic patterns, clinical heterogeneity, molecular alterations, and therapeutic implications

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of motor neurons, resulting in global health burden and limited post-diagnosis life expectancy. Although primarily sporadic, familial ALS (fALS) cases suggest a genetic basis. This review focuses on SOD1, the first gene found to be associated with fALS, which has been more recently confirmed by genome sequencing. While informative, databases such as ALSoD and STRENGTH exhibit regional biases. Through a systematic global examination of SOD1 mutations from 1993 to 2023, we found different geographic distributions and clinical presentations. Even though different SOD1 variants are expressed at different protein levels and have different half-lives and dismutase activities, these alterations lead to loss of function that is not consistently correlated with disease severity. Gain of function of toxic aggregates of SOD1 resulting from mutated SOD1 has emerged as one of the key contributors to ALS. Therapeutic interventions specifically targeting toxic gain of function of mutant SOD1, including RNA interference and antibodies, show promise, but a cure remains elusive. This review provides a comprehensive perspective on SOD1-associated ALS and describes molecular features and the complex genetic landscape of SOD1, highlighting its importance in determining diverse clinical manifestations observed in ALS patients and emphasizing the need for personalized therapeutic strategies.

Clinical Association of Biochemical Variations Among Multilocus Genotypes of Antioxidant Enzymes with Susceptibility of Cataract in Hyperglycemia

Hyperglycemia plays a pronounced role in accelerating the process of aging due to high oxidative stress which triggers dyslipidemia and subsequently led to the progression of cataract. The aim of this study was to investigate lipid profile and its relationship with genotypes of SOD1, GPX1, and CAT variants in cataract patients. Total n = 680 samples were screened in four groups: senile cataract (SC), diabetic cataract (DC), type 2 diabetes mellitus (DM), and controls (CL). Lipid profile was estimated and compared between groups, and its correlation was tested with glycemic markers. Association of SOD1 50 bp Indel, GPX1 (rs1800668), and CAT (rs1001179) genotypes with all clinical variables was investigated in cataract groups by regression statistics in SPSS® 16.0. Comparative analysis revealed that amount of total cholesterol and low-density lipoprotein parameters were significantly higher in both groups of cataracts when compared with controls (p < 0.01). Statistically higher levels of triglycerides were also evident in DM patients as compared with other three groups (p < 0.01). Significant weak positive correlation of glycated hemoglobin, fasting (FBG), and random blood glucose (RBG) levels was observed with triglycerides in DM (r = 0.16), SC (r = 0.15), and DC (r = 0.18) groups. Mutant genotype of SOD1 and CAT variants indicated significant association with TC, whereas GPX1 variant with FBG levels in accelerating predisposition of cataract in patients with diabetes (OR > 1.0). Outcomes suggested that TG may serve as a potential biomarker of lipid profile with manifestation of cataract in type 2 DM. Furthermore, hypercholesterolemia and hypertriglyceridemia demonstrated an inducing role in the pathogenesis of cataract with aging in hyperglycemia.

Predisposition of SOD1, GPX1, CAT genetic variants and their haplotypes in cataractogenesis of type 2 diabetes mellitus in Pakistan

AIMS

Cataract formation is accelerated by hyperglycemia due to the excessive production of oxidative stress. This study aimed to examine the underlaying role of glutathione peroxidase 1 (GPX1) rs1800668, catalase (CAT) rs1001179 and superoxide dismutase 1 (SOD1) 50 bp Indel promotor region variants in the pathogenesis of cataract in patients with diabetes.

METHODS

A population-based case-control study of n=680 individuals was conducted which comprised of four respective groups: type 2 diabetes mellitus, diabetic cataract, senile cataract patients and controls. Screening of genotypes was performed by allele-specific (AS) and conventional polymerase chain reaction (PCR). Statistical testing was carried out using SPSS© 20.0, MedCal© and SNPStats© software's. Bioinformatics analysis of linkage disequilibrium was done by HaploView© software 7.0.

RESULTS

GPX1 (rs1800668) showed significant association with higher susceptibility of opacification in type 2 diabetes mellitus (χ²=23.0, Adjusted OR=1.63, 95% CI: 1.05-2.49, p<0.001). A protective role was anticipated by CAT variant (rs1001179) for the development of resistance against the pathogenicity of cataract with diabetes (χ² = 107, Adjusted OR=0.17, 95% CI: 0.10-0.29, p<0.001). Linkage disequilibrium (LD) plot of GPX1 and CAT variants revealed that CTC-CTT haplotypes demonstrated the presence of linkage (D'=1.0) and co-inheritance (LOD=13.84) in patients of diabetic cataract.

CONCLUSIONS

GPX1 (rs1800668) variant may serve as an antioxidant biomarker for the assessment of risk for cataract in type 2 diabetes mellitus. GPX1 enzyme owed an antioxidant activity which can reduce the oxidative stress and hence could develop resistance in cataractogenesis. The findings could be beneficial as a potential target to the future pharmacogenomic studies of cataract prevention and eradication in diabetes mellitus.

Screening for Novel LOX and SOD1 Variants in Keratoconus Patients from Brazil

Purpose

To investigate the presence of the variants of lysyl oxygenase (LOX) and superoxide dismutase 1 (SOD1) genes in Brazilian patients with advanced keratoconus.

Methods

Donor genomic DNA extracted from blood samples was screened for 5'UTR, exonic LOX, and SOD1 variants in a subset of 26 patients presenting with advanced keratoconus (KISA > 1000% and I–S > 2.0) by Sanger sequencing. The impact of non-synonymous amino acid changes was evaluated by SIFT, PMUT, and PolyPhen algorithms. The Mutation Taster tool was used to evaluate the potential impact of formation of new donor and acceptor splice sites in the promoter region of affected volunteers carrying sequence variants. A 7-base SOD1 deletion (IVS2 + 50del7bp) previously associated with keratoconus was screened in 140 patients presenting classical keratoconus by gel fragment analysis, and positive samples were sequenced for confirmation.

Results

We found an unreported missense variant in LOX exon 6 in one heterozygous patient, leading to substitution of proline with threonine at residue 392 (p. Thr392Pro) of LOX protein sequence. This mutation was predicted to be potentially damaging to LOX protein. Another LOX variant, Arg158Gln, was also detected in another patient but predicted to be non-pathogenic. Two additional new polymorphisms in LOX 5'UTR region (–116C > T and –58C > T) were found in two patients presenting with advanced keratoconus and were predicted to modulate or create donor/acceptor splice sites in LOX transcripts. Additionally, SOD1 deletion was detected in one patient presenting with severe keratoconus, not in control samples.

Conclusion

We described three novel LOX polymorphisms identified for the first time in Brazilian patients with advanced keratoconus, as well as a previously described SOD1 deletion strongly associated with keratoconus. A possible role of these variants in modulating transcript levels in the cornea of affected individual requires further investigation.

Influence of a 50bp Ins/Del polymorphism at promoter of the superoxide dismutase-1 on gene expression and risk of heroin dependency

OBJECTIVE

Superoxide dismutase-1 (SOD1, OMIM: 147450) is one of the major antioxidant enzymes, which plays a vital role in clearance of reactive oxygen species. A genetic polymorphism of 50 bp insertion/deletion (Ins/Del) in the promoter region of the SOD1 was reported. The aims of the present study are to evaluate the influence of this polymorphism on the SOD1 mRNA levels in human peripheral blood cells and its association with risk of heroin dependency.

METHODS

The present study consisted of 47 healthy students of Shiraz University (south-west Iran) for investigating the association between the Ins/Del polymorphism on expression level of SOD1, also a total of 442 heroin dependent and 799 healthy controls were included in a case-control study investigating the association between the study polymorphism and risk of dependency to heroin. The quantitative SOD1 mRNA expression levels were investigated using quantitative real-time PCR.

RESULTS

Statistical analysis revealed a significant difference between the study genotypes (t = 5.17; df = 45; P < 0.001). The Del allele of the study polymorphism decreased approximately 33% of the SOD1 mRNA levels of the gene in the heterozygote individuals. Statistical analysis indicating that in both genders, neither the Ins/Del nor the Del/Del genotypes was associated with the risk of heroin addiction.

CONCLUSIONS

The present study indicating that although the Ins/Del polymorphism of SOD1 is associated with the SOD1 expression levels, this polymorphism is not associated with the risk of dependency to heroin.