A questionnaire survey on patients' willingness to pay with reference to the waiting time of public in-vitro fertilization treatment in Hong Kong.

OBJECTIVE: To evaluate patients' willingness to pay (WTP) with reference to the waiting time of public in-vitro fertilisation (IVF) treatment in order to improve the public IVF service in Hong Kong. STUDY DESIGN: A prospective multi-centred questionnaire survey. Infertile women attending infertility clinics of nine public hospitals in Hong Kong between October 2017 and August 2018 were asked to complete a questionnaire in their first clinic visit. RESULTS: Out of 1092 respondents, 10.4 % had private IVF cycles prior to their first visit at public hospitals. In general, patients were willing to pay more for a shorter waiting time for public IVF service. The proportion of respondents who were willing to pay more than HK$10,000 (US$1282) for one IVF cycle increased from 54.6% to 80.7% if the waiting time for public IVF service were hypothetically shortened from four years to one year. Likewise, 22.5 % versus 45.5 % were willing to pay more than HK$ 25,000 (US$3205) with a waiting time of four versus one year respectively. Assuming the cost per IVF cycle was HK$ 25,000 (US$3205), 23.4 % of respondents could afford one IVF cycle, 40.0 % of them could afford two IVF cycles and 31.5 % could afford three IVF cycles. A multivariate regression model demonstrated that only family income and presence of existing child(ren) were significant independent determinants of the maximum amount that an individual was willing to pay for IVF (p < 0.05). Those with family monthly income below HK$100,000 ($12,820) were less than half as likely, and those without existing child(ren) were more than double as likely, to be willing to pay higher for IVF. CONCLUSION: Patients were willing to pay more for a shorter waiting time for public IVF service. Those with family income below HK$100,000 (US$ 12,820) were less than half as likely, and those without existing children were more than double as likely, to be willing to pay higher for IVF.

Serum concentrations of cycloserine and outcome of multidrug-resistant tuberculosis in Northern Taiwan.

BACKGROUND: Therapeutic drug monitoring (TDM) has been advocated to promote the efficacy of anti-tuberculosis agents. Cycloserine (CS) is a second-line anti-tuberculosis drug whose serum concentrations in tuberculosis (TB) patients are largely unknown. OBJECTIVES: To investigate serum CS concentrations after drug ingestion in TB patients. METHODS: Multidrug-resistant TB patients who were taking CS in a tertiary care centre in northern Taiwan between 1 April 2009 and 31 October 2009 were enrolled in the study. Serum CS concentrations were measured at 2 and 6 h after drug administration. RESULTS: Of 32 patients enrolled, 23 were males and 9 females. The mean CS dose was 8.8 ± 1.3 mg/kg. The mean serum concentrations at 2 and 6 h were respectively 19.7 ± 8.3 and 18.1 ± 8.7 µg/ml. Seven patients (22%) had serum drug concentrations that were higher at 6 h than at 2 h, 12 (38%) had peak serum concentrations within the recommended range of 20-35 µg/ml; 18 patients (56%) had concentrations <20 µg/ml at both 2 h and 6 h; and 2 patients (6%) had at least one measurement >35 µg/ml. CONCLUSION: Lower than recommended serum CS concentrations and delayed absorption were common. It is essential to develop practical TDM to maintain proper serum drug concentrations.

The tumor suppressor, TAX1BP2, is a novel substrate of ATM kinase.

DNA damage repair response is a crucial process for cancer prevention. One of the key regulators of this process is ataxia telangiectasia mutated (ATM) kinase, which modulates the p53 level by direct and indirect phosphorylation. Recent data showed that ATM also localizes at the centrosome, but the function remains elusive. TAX1BP2 was initially identified as a novel centrosomal protein that interacts directly with the human T-cell leukemia virus type 1 (HTLV-1)-encoded oncoprotein, Tax, and inhibits centrosome overduplication. Subsequently, TAX1BP2 was found to be a tumor suppressor in hepatocellular carcinoma, and accumulation of TAX1BP2 was observed upon chemotherapeutic drug treatment. Here, we provide evidence that TAX1BP2 is a direct phosphorylation substrate of ATM. The protein level of TAX1BP2 is significantly upregulated in response to DNA damaging agents. Serine-922 of TAX1BP2 is the phosphorylation site of ATM, and such phosphorylation modulates the protein stability, ubiquitination and tumor suppressor activity of TAX1BP2. Taken together, we demonstrate for the first time that TAX1BP2 is a novel effector of ATM in DNA damage response and delineated a new mechanism by which ATM stabilizes the tumor suppressor TAX1BP2.

Mitochondrial dysfunction-induced amphiregulin upregulation mediates chemo-resistance and cell migration in HepG2 cells.

The aim of this study was to investigate the contribution of mitochondrial dysfunction to chemoresistance and migration of hepatoma cells. We found that inhibition of mitochondrial respiration and mitochondrial DNA (mtDNA) depletion resulted in induction of amphiregulin (AR) expression in HepG2 cells. Upon oligomycin treatment of HepG2 cells, the cytosolic Ca(2+) was significantly raised after 30 min, and the intracellular level of reactive oxygen species (ROS) was elevated 2.2-fold after 4 h. Moreover, the condition medium of oligomycin-treated HepG2 cells was found to stimulate the migration of SK-Hep-1 cells. On the other hand, oligomycin-induced cisplatin-resistance and cell migration of HepG2 cells were attenuated by AR-specific RNA interference (#L-017435, Dharmacon) and a neutralizing antibody (MAB262, R&D Systems), respectively. Together, these findings suggest that mitochondrial dysfunction induced Ca(2+) mobilization, and ROS overproduction, which modulated the chemo-resistance and migration of hepatoma cells through the induction and activation of AR.

Age and founder effect of SOD1 A4V mutation causing ALS.

BACKGROUND: The alanine to valine mutation at codon 4 (A4V) of SOD1 causes a rapidly progressive dominant form of amyotrophic lateral sclerosis (ALS) with exclusively lower motor neuron disease and is responsible for 50% of SOD1 mutations associated with familial ALS in North America. This mutation is rare in Europe. The authors investigated the origin (geographic and time) of the A4V mutation. METHODS: Several cohorts were genotyped: North American patients with confirmed A4V mutation (n = 54), Swedish (n = 3) and Italian (n = 6) A4V patients, patients with ALS with SOD1 non-A4V mutations (n = 66) and patients with sporadic ALS (n = 96), healthy white (n = 96), African American (n = 17), Chinese (n = 53), Amerindian (n = 11), and Hispanic (n = 12) subjects. High-throughput SNP genotyping was performed using Taqman assay in 384-well format. A novel biallelic CA repeat in exon 5 of SOD1, tightly linked to A4V, was genotyped on sequencing gels. Association statistics were estimated using Haploview. p Values less than 0.05 were considered significant. Age of A4V was estimated using a novel method based on r(2) degeneration with genetic distance and a Bayesian method incorporated in DMLE+. RESULTS: A single haplotype of 10 polymorphisms across a 5.86-cM region was associated with A4V (p = 3.0e-11) when white controls were used, suggesting a founder effect. The strength of association of this haplotype progressively decreased when African American, Chinese, Hispanic, and Amerindian subjects were used as controls. The associated European haplotype was different from the North American haplotype, indicating two founder effects for A4V (Amerindian and European). The estimated age of A4V with the r(2) degeneration method was 458 +/- 59 years (range 398-569) and in agreement with the Bayesian method (554-734 years with 80-90% posterior probability). CONCLUSIONS: North American SOD1 alanine to valine mutation at codon 4 descended from two founders (Amerindian and European) 400-500 years ago.

Riluzole metabolism and CYP1A1/2 polymorphisms in patients with ALS.

Riluzole is the only FDA approved drug for the treatment of amyotrophic lateral sclerosis. Riluzole is assumed to be mainly metabolized by the liver cytochrome CYP1A2 and by the extra-hepatic cytochrome CYP1A1. CYP1A2 and CYP1A1 genetic polymorphisms are known, but their relationship to riluzole metabolism in ALS patients has not been investigated. The aim of this study was to determine whether the polymorphisms of the CYP1A2 and the CYP1A1 genes in ALS patients are associated with riluzole metabolic profiles. Thirty-two patients with a diagnosis of probable or definite ALS and who were on riluzole, participated in the study. Trough and peak plasma riluzole levels were measured using analytical chromatography-mass spectrometry methods. Association of the genotypes of the SNPs spanning the CYP1A1 and CYP1A2 genes (including one SNP in the intergenic region) with mean riluzole peak and trough levels was studied using ANOVA and Tukey's HSD. The mean peak riluzole level was 202+/-111 ng/ml and mean trough level 54.3+/-37.5 ng/ml. Our data do not support any association of the four CYP1A1 and CYP1A2 polymorphisms with the riluzole metabolic profile. In conclusion, genetic variations in CYP1A1 and CYP1A2 genes do not seem to influence riluzole levels. Further work is needed to better understand the genetic regulation of CYP1A enzymes and their role in riluzole metabolism.

Changes of microstructure and mineralized tissue in the middle and late phase of osteoporotic fracture healing in rats.

BACKGROUND: With osteoporosis emerged as one of the most important health issues, more and more investigations are focusing on osteoporotic fracture healing. However, there are few studies on the changes of microstructure and mineralized tissue of newly formed callus. OBJECTIVE: We established an osteoporotic fracture rat model to evaluate the changes of microstructure and mineralized tissue during osteoporotic fracture healing. MATERIALS AND METHODS: A mid-shaft femur fracture model was established 12 weeks after ovariectomy as an osteoporotic fracture group (OPF group). Femurs were then harvested at 4 weeks, 8 weeks and 12 weeks after fracture for peripheral quantitative computed tomography (pQCT), micro-computed tomography (MicroCT), histology and biomechanical test. A sham-operated group was used for comparison, i.e. the normal fracture group (NF group). RESULTS: The pQCT-derived total external callus area in the OPF group was smaller than that in the NF group at 4 weeks after fracture (P<0.05), whereas it was 21% larger in the OPF group than that in the NF group at 12 weeks after fracture (P<0.01). The pQCT-derived bone mineral density in the OPF group was significantly inferior to the NF group at all the time points (P<0.05 for all the time points, respectively). MicroCT data, at 12 weeks after fracture, showed the total callus, bony callus, and newly formed bone was approximately 20% lower in the OPF group than that in the NP group, and the total connectivity was 56% lower in the OPF group as compared to the NF group. Biomechanical test data, at 12 weeks after fracture, showed that the failure load of the left femur of OPF group was 17% less compared to that of the NF group (P<0.01), and 15% lower bending stiffness (P<0.05), 20% lower bending stress (P<0.01), and 28% lower energy at failure (P<0.01) were observed in the OPF group as compared to the NF group. CONCLUSION: The decrease in mineralized tissue and the not well connected microstructure in newly formed callus may explain the decline of mechanical impairment of fracture healing in the ovariectomized rats.

Lack of association of VEGF promoter polymorphisms with sporadic ALS.

The authors tested the association of three vascular endothelial growth factor (VEGF) promoter polymorphisms with sporadic ALS (SALS) to verify the results of a previous study and to investigate their modifier effects on the subphenotypes of SALS in a large family-based and case-control cohort of North American white subjects (N = 1,603). They did not find any association of the VEGF promoter polymorphisms with SALS or its subphenotypes, suggesting that they do not have a direct causal role in ALS.

Paraoxonase cluster polymorphisms are associated with sporadic ALS.

BACKGROUND: Paraoxonases (PONs) are involved in the detoxification of organophosphate pesticides and chemical nerve agents. Due to a reported possible twofold increased risk of ALS in Gulf War veterans and the associations of PON1 polymorphisms with the neurologic symptom complex of the Gulf War syndrome, the authors investigated the association between sporadic ALS (SALS) and PON gene cluster variants in a large North American Caucasian family-based and case-control cohort (N = 1,891). METHODS: Clinically definite and probable ALS was diagnosed according to the revised El Escorial criteria, exclusion of family history of ALS, and SOD1 mutation analysis. Single nucleotide polymorphism (SNP) genotyping was done using TaqMan assays on ABI7900HT. Data were analyzed using SPSS, Haploview, FBAT, and THESIAS. RESULTS: A haploblock of high linkage disequilibrium (LD) spanning PON2 and PON3 was associated with SALS. The SNPs rs10487132 and rs11981433 were in strong LD and associated with SALS in the trio (parents-affected child triad) model. The association of rs10487132 was replicated in 450 nuclear pedigrees comprising trios and discordant sibpairs. No association was found in case-control models, and their haplostructure was different from that of the trios with overall reduced LD. Resequencing identified an intronic variant (rs17876088) that differentiated between detrimental and protective SALS haplotypes. CONCLUSION: This study demonstrates evidence of significant association of variants in the Paraoxonase gene cluster with sporadic ALS and is compatible with the hypothesis that environmental toxicity in a susceptible host may precipitate ALS.

Flavonoids derived from herbal Epimedium Brevicornum Maxim prevent OVX-induced osteoporosis in rats independent of its enhancement in intestinal calcium absorption.

AIM: Factorial design was used to test our hypothesis whether a group of flavonoids (FE) derived from herbal Epimedium Brevicornum Maxim exerted its preventive effects on estrogen-deficiency-induced osteoporosis mainly through an enhancement in intestinal calcium absorption. MATERIALS AND METHODS: Forty-five 12-month-old female Wistar rats were used and randomly assigned into sham-operated group and four ovariectomy (OVX) subgroups, i.e. OVX with vehicle (OVX group), OVX with FE (FE group), OVX with calcium supplement (CS group), and OVX with FE and CS (FE + CS group). Daily oral administration of FE (10 mg/kg/day) and/or CS (56 mg/kg/day) started on day 4 after OVX for 12 weeks. Before sacrificing the animals, urine and serum samples were collected for assaying indicators related to intestinal calcium absorption, regulator for calcium homeostasis, and markers of bone turnover. The left proximal femur was dissected for evaluation of the primary end-point (failure force), the second end-points (pQCT-quantified densitometry, geometry, and micro-CT-quantified 3-D trabecula micro-architecture), and pQCT-defined cross-sectional envelope. RESULTS: FE was found to be able to prevent OVX-induced reduction in failure force as well as the above second end-points, without resulting in an increased uterus weight. CS had no preventive effect on OVX-induced reduction in failure force. Two-way factorial interaction analysis between FE and CS showed that the un-enhanced suppression of parathyroid hormone for calcium homeostasis did not provide link between the enhanced intestinal calcium absorption and the enhanced inhibition of bone resorption in the present study. Furthermore, the discrepancies between the enhanced intestinal calcium absorption and the un-enhanced end-point measures as well as anabolic effect were also revealed by the interaction analysis. CONCLUSION: The present study suggested that FE inhibited bone resorption, stimulated bone formation, and accordingly prevented osteoporosis without hyperplastic effect on uterus in the OVX rat model, which was however independent of an enhancement in intestinal calcium absorption.

Baseline BMD and bone loss at distal radius measured by peripheral quantitative computed tomography in peri- and postmenopausal Hong Kong Chinese women.

The current study was designed to investigate the rate of bone loss in distal radius and its association with baseline volumetric bone mineral density (BMD) and years since menopause (YSM) in peri- and postmenopausal women using precise and multislice peripheral quantitative computed tomography (pQCT; Densiscan 2000). Two hundred and five healthy Hong Kong Chinese perimenopausal ( n = 26) and postmenopausal ( n = 179) women within 10 years of the onset of menopause were recruited. Anthropometric parameters and menstrual status were also measured. The linear regression model derived from the baseline volumetric BMD revealed a significant and slightly better correlation with YSM than age, with a YSM-related annual decline of 2.56%, 1.82% and 0.65% in trabecular BMD (tBMD), integral BMD (iBMD) and cortical BMD (cBMD), respectively. Follow-up measurements after a time interval of 12 months showed that the rate of bone loss was higher than the annual decline in BMD calculated from the baseline BMD, with decreases of 2.89%, 2.16% 0.91% in tBMD, iBMD and cBMD, respectively. Baseline BMD was associated with age or YSM ( r ranges from -0.283 to -0.502; p<0.001 in all cases), but no relationship was found between annual rate of bone loss and age or YSM. The rate of bone loss did not correlate with baseline volumetric BMD values or YSM after dividing the subjects into fast bone losers (with annual tBMD loss > or =3%), normal bone losers (with annual tBMD loss > or = 1% but <3%) or slow bone losers (with annual tBMD loss <1%). The rate of bone loss was greater in both trabecular and cortical bone of postmenopausal women within the first 3 menopausal years but was only significant in the iBMD as compared with perimenopausal and postmenopausal women over 7 years after onset of menopause. The percentage distribution of slow and fast bone losers was not found to be associated with YSM. As a total of only 4 fracture cases were documented, the study could not provide conclusive information on whether perimenopausal and early postmenopausal baseline volumetric BMD or rate of bone loss determines the development of osteoporosis or fracture occurrence.

The gene encoding alsin, a protein with three guanine-nucleotide exchange factor domains, is mutated in a form of recessive amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS) are neurodegenerative conditions that affect large motor neurons of the central nervous system. We have identified a familial juvenile PLS (JPLS) locus overlapping the previously identified ALS2 locus on chromosome 2q33. We report two deletion mutations in a new gene that are found both in individuals with ALS2 and those with JPLS, indicating that these conditions have a common genetic origin. The predicted sequence of the protein (alsin) may indicate a mechanism for motor-neuron degeneration, as it may include several cell-signaling motifs with known functions, including three associated with guanine-nucleotide exchange factors for GTPases (GEFs).

Novel mutations in spastin gene and absence of correlation with age at onset of symptoms.

Autosomal dominant hereditary spastic paraplegia is genetically heterogeneous, with at least five loci identified by linkage analysis. Recently, mutations in spastin were identified in SPG4, the most common locus for dominant hereditary spastic paraplegia that was previously mapped to chromosome 2p22. We identified five novel mutations in the spastin gene in five families with SPG4 mutations from North America and Tunisia and showed the absence of correlation between the predicted mutant spastin protein and age at onset of symptoms.

Linkage of familial amyotrophic lateral sclerosis with frontotemporal dementia to chromosome 9q21-q22.

CONTEXT: Occasionally, 2 or more major neurodegenerative diseases arise simultaneously. An understanding of the genetic bases of combined disorders, such as amyotrophic lateral sclerosis (ALS) with frontotemporal dementia (FTD), will likely provide insight into mechanisms of these and related neurodegenerative diseases. OBJECTIVE: To identify loci that contain genes whose defects cause ALS. DESIGN: A genome-wide linkage analysis of 2 data sets from an ongoing study begun in the mid-1980s at 4 university research centers. SUBJECTS: An initial subset of 16 families (549 people) potentially informative for genetic analysis, in which 2 or more individuals were diagnosed as having ALS, identified from a Boston data set of 400 families and 4 families potentially informative (244 people) subsequently identified from a Chicago data set of more than 300 families to test a hypothesis based on findings from the Boston families. MAIN OUTCOME MEASURES: Linkage calculations assuming autosomal dominant inheritance with age-dependent penetrance (a parametric logarithm-of-odds [lod] score of 1.0 or greater required for further study of a potential locus); crossover analysis involving the ALS-FTD locus. RESULTS: In a set of families in which persons develop both ALS and FTD or either ALS or FTD alone, a genetic locus that is linked to ALS with FTD located between markers D9S301 and D9S167 was identified on human chromosome 9q21-q22. Families with ALS alone did not show linkage to this locus. Crossover analysis indicates this region covers approximately 17 cM. CONCLUSION: These data suggest that a defective gene located in the chromosome 9q21-q22 region may be linked to ALS with FTD. JAMA. 2000;284:1664-1669.

Multiple transcripts of the human Cu,Zn superoxide dismutase gene.

We have identified five alternatively spliced transcripts of the gene for human Cu,Zn superoxide dismutase (SOD1), a causative gene for autosomal dominant amyotrophic lateral sclerosis (ALS). The splice variants of wild-type or mutant SOD1 were expressed in a tissue-specific manner; therefore, their expression may be regulated to modify SOD1 function. In addition, the expression in the brain implies that variants may play a role in the nervous system, the region involved in ALS. Immunoblot study of HeLa cells transfected with two variants encoding C-terminal truncated proteins did not show the proteins of expected size. However, this observation is consistent with the previous study of C-terminal truncated mutant proteins that cause ALS, suggesting that both variant and mutant proteins may share certain properties, such as instability or insolubility in the cytosol. These findings suggest that the splice variants may contribute to a physiological function of SOD1 or to a pathological mechanism in ALS.

Increased reactive oxygen species in familial amyotrophic lateral sclerosis with mutations in SOD1.

Amyotrophic lateral sclerosis (ALS) is a paralytic disorder characterized by degeneration of large motor neurons of the brain and spinal cord. A subset of ALS is inherited (familial ALS, FALS) and is associated with more than 70 different mutations in the SOD1 gene. Here we report that lymphoblast cell lines derived from FALS patients with 16 different mutations in SOD1 gene exhibit significant increase of intracellular reactive oxygen species (ROS) compared with sporadic ALS (SALS) and normal controls (spouses of ALS patients). The ROS generation did not correlate with SOD1 activity. Further, cells incubated with vitamin C, catalase or the flavinoid quercetin significantly reduced ROS in all groups. The catalase inhibitor 3-amino-1,2,4-triazole resulted in a ten-fold increase of ROS in all groups. Neither L-nitroarginine, a nitric oxide synthase inhibitor or vitamin E altered the ROS levels. Thus, these studies suggest that hydrogen peroxide (H(2)O(2)) is a major ROS elevated in FALS lymphoblasts and it may contribute to the degeneration of susceptible cells. Further, we postulate a mechanism by which increased H(2)O(2) could be generated by mutant SOD1.

Lack of association between apolipoprotein E genotype and sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neuro-degenerative disorder with both sporadic and familial forms. Approximately 20% of autosomal dominant ALS is caused by mutations in the Cu/Zn superoxide dismutase (SOD1) gene. The causes of the remaining forms of ALS are unknown. The apolipoprotein E (APOE) gene is a known genetic risk factor for Alzheimer disease (AD), another neuro-degenerative disease. The APOE-4 allele increases risk and decreases age at onset in AD. Studies examining ALS and APOE have failed to show a significant effect of APOE on overall risk in ALS. Studies examining the effect of APOE-4 on site of onset in ALS (bulbar or limb) have been contradictory, with some studies showing an APOE association with bulbar onset and others showing no effect. Sample size was limited in these previous reports, particularly with respect to the number of bulbar onset cases (n = 33, 34 and 53). The present study examines a large collaborative data set of ALS patients (n = 363; 95 with bulbar onset) and age-matched neurologically normal controls. The results for these data showed no significant differences in the percentage of subjects with the APOE-4/4 and APOE-4/X genotypes (X = APOE-2 or APOE-3) when comparing cases and controls in both the overall data set or in the data set stratified by site of onset. Similarly, logistic regression analysis in the overall and stratified data set while controlling for sex showed no increase or decrease in risk of ALS associated with the APOE-4 allele. In addition, there were no significant differences in age at onset between patients with APOE-X/X, and APOE-4/4 or APOE-4/X genotypes, overall or stratified by site of onset. We conclude based on these data that the APOE gene is not a major genetic risk factor for site of onset in ALS.

Exclusion of the expansion of CAG/CTG repeats at thirteen loci on chromosome 12 as a candidate genetic mutation in scapuloperoneal spinal muscular atrophy with anticipation.

Scapuloperoneal spinal muscular atrophy (SPSMA) is a neuromuscular disorder characterized by weakness in the distribution of shoulder girdle and peroneal muscles. We have previously described a large New England kindred with autosomal dominant SPSMA and have subsequently linked this family trait to 12q24.1-q24.31. In this family, disease expression becomes more severe and progressive in successive generations, suggesting genetic anticipation. Accordingly, we have investigated the thirteen known CAG/CTG repeat loci on chromosome 12 that could be tested by using the polymerase chain reaction as candidate genetic mutations in SPSMA. None of these loci is expanded.

Exon 5 encoded domain is not required for the toxic function of mutant SOD1 but essential for the dismutase activity: identification and characterization of two new SOD1 mutations associated with familial amyotrophic lateral sclerosis.

Two new mutations in the gene encoding cytoplasmic Cu,Zn superoxide dismutase (SOD1) have been discovered in patients with familial amyotrophic lateral sclerosis (FALS). These mutations result in the truncation of most of the polypeptide segment encoded by exon 5, one by the formation of a stop codon in codon 126 (L126Z) and the other by inducing alternative splicing in the mRNA (splicing junction mutation). These two mutants of SOD1 result in a FALS phenotype similar to that observed in patients with missense mutations in the SOD1 gene, establishing that exon 5 is not required for the novel toxic functions of mutant SOD1 associated with ALS. These mutant enzymes are present at very low levels in FALS patients, suggesting elevated toxicity compared to mutant enzymes with single site substitutions. This increased toxicity likely arises from the extreme structural and functional changes in the active site channel, beta-barrel fold, and dimer interface observed in the mutant enzymes, including the loss of native dismutase activity. In particular, the truncation of the polypeptide chain dramatically opens the active site channel, resulting in a marked increase in the accessibility and flexibility of the metal ions and side chain ligands of the enzyme active site. These structural changes are proposed to cause a decrease in substrate specificity and an increase in the catalysis of harmful chemical reactions such as peroxidation.