Down syndrome as a genetic model to evaluate the role of oxidative stress and transsulfuration abnormalities in autism spectrum disorder: A 10-year longitudinal cohort study

Intricacies of aging and Down syndrome

Down syndrome is the most frequently occurring genetic condition, with a substantial escalation in risk associated with advanced maternal age. The syndrome is characterized by a diverse range of phenotypes, affecting to some extent all levels of organization, and its progeroid nature - early manifestation of aspects of the senile phenotype. Despite extensive investigations, many aspects and mechanisms of the disease remain unexplored. The current review aims to provide an overview of the main causes and manifestations of Down syndrome, while also examining the phenomenon of accelerated aging and exploring potential therapeutic strategies.

Constitutional chromosomal anomalies in children, fetal alcohol syndrome, and maternal toxicant exposures: A longitudinal cohort study

DNA alterations in gametes, which may occur either spontaneously or as a result of exposure to genotoxicants, can lead to constitutional chromosomal anomalies in the offspring. Alcohol is an established genotoxicant. The goal of this hypothesis-testing longitudinal cohort study was to evaluate the effect of significant/sustained maternal alcohol exposure on clinically diagnosed constitutional chromosomal anomalies among children diagnosed with fetal alcohol syndrome (FAS). De-identified eligibility and claim healthcare records, prospectively generated from the 1990-2012 Florida Medicaid system within the Independent Healthcare Research Database (IHRD), were analyzed. Children examined were continuously eligible with ≥ 8 outpatient office visits during the 96-month period following birth. Among these children, 377 were diagnosed with FAS and 137,135 were not. The incidence rate of chromosomal anomalies involving segregation (trisomy 13, 18, or 21, n = 625), microdeletions (microdeletion syndromes, n = 39), and point mutations (sickle-cell anemia/cystic fibrosis, n = 2570) were examined using frequency risk ratio (RR) and logistic regression (adjusted odds ratio (aOR) for sex, race, residence, socioeconomic/environmental exposure status, and birth date) models. The incidence rates of chromosomal anomalies involving segregation (RR=5.92, aOR=5.85) and microdeletions (RR=41.6, aOR=34.1) were significantly increased in the FAS cohort as compared to the non-diagnosed cohort, but there was no difference in the incidence rate of point mutations (RR=1.14, aOR=1.29). Maternal toxicant exposure should be considered in the etiology of constitutional chromosomal anomaly in offspring.

Colon Cancer Risk Following Intestinal Clostridioides difficile Infection: A Longitudinal Cohort Study

Background

The gut microbiome may play an important role in the etiology and progression of colon cancer. The present hypothesis-testing study compared the colon cancer incidence rate among adults diagnosed with intestinal Clostridioides (formerly Clostridium) difficile (Cdiff) (the Cdiff cohort) to adults not diagnosed with intestinal Cdiff infection (the non-Cdiff cohort).

Methods

De-identified eligibility and claim healthcare records within the Independent Healthcare Research Database (IHRD) from a longitudinal cohort of adults (the overall cohort) enrolled in the Florida Medicaid system between 1990 through 2012 were examined. Adults with ≥ 8 outpatient office visits over 8 years of continuous eligibility were examined. There were 964 adults in the Cdiff cohort and 292,136 adults in the non-Cdiff cohort. Frequency and Cox proportional hazards models were utilized.

Results

Colon cancer incidence rate in the non-Cdiff cohort remained relatively uniform over the entire study period, whereas a marked increase was observed in the Cdiff cohort within the first 4 years of a Cdiff diagnosis. Colon cancer incidence was significantly increased (about 2.7-fold) in the Cdiff cohort (3.11 per 1,000 person-years) compared to the non-Cdiff cohort (1.16 per 1,000 person-years). Adjustments for gender, age, residency, birthdate, colonoscopy screening, family history of cancer, and personal history of tobacco abuse, alcohol abuse/dependence, drug abuse/dependence, and overweight/obesity, as well as consideration of diagnostic status for ulcerative and infection colitis, immunodeficiency, and personal history of cancer did not significantly change the observed results.

Conclusions

This is the first epidemiological study associating Cdiff with an increased risk for colon cancer. Future studies should further evaluate this relationship.

Untargeted Metabolomic Analysis Reveals the Metabolic Disturbances and Exacerbation of Oxidative Stress in the Cerebral Cortex of a BTBR Mouse Model of Autism

The etiology and pathology of autism spectrum disorders (ASDs) are still poorly understood, which largely limit the treatment and diagnosis of ASDs. Emerging evidence supports that abnormal metabolites in the cerebral cortex of a BTBR mouse model of autism are involved in the pathogenesis of autism. However, systematic study on global metabolites in the cerebral cortex of BTBR mice has not been conducted. The current study aims to characterize metabolic changes in the cerebral cortex of BTBR mice by using an untargeted metabolomic approach based on UPLC-Q-TOF/MS. C57BL/6 J mice were used as a control group. A total of 14 differential metabolites were identified. Compared with the control group, the intensities of PI(16:0/22:5(4Z,7Z,10Z,13Z,16Z)), PC(22:6(4Z,7Z,10Z,13Z,16Z,19Z)/18:1(9Z)), PA(16:0/18:1(11Z)), 17-beta-estradiol-3-glucuronide, and N6,N6,N6-trimethyl-L-lysine decreased significantly (p < 0.01) and the intensities of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline, LysoPC(20:4(5Z,8Z,11Z,14Z)/0:0), adenosine monophosphate, adenosine-5'-phosphosulfate, LacCer(d18:1/12:0),3-dehydro-L-gulonate, N-(1-deoxy-1-fructosyl)tryptophan, homovanillic acid, and LPA(0:0/18:1(9Z)) increased significantly (p < 0.01) in the BTBR group. These changes in metabolites were closely related to perturbations in lipid metabolism, energy metabolism, purine metabolism, sulfur metabolism, amino acid metabolism, and carnitine biosynthesis. Notably, exacerbation of the oxidative stress response caused by differential prooxidant metabolites led to alteration of antioxidative systems in the cerebral cortex and resulted in mitochondrial dysfunction, further leading to abnormal energy metabolism as an etiological mechanism of autism. A central role of abnormal metabolites in neurological functions associated with behavioral outcomes and disturbance of sulfur metabolism and carnitine biosynthesis were found in the cerebral cortex of BTBR mice, which helped increase our understanding for exploring the pathological mechanism of autism.

Differential expression of cystathionine beta synthase in adolescents with Down syndrome: impact on adiposity

Purpose

Obesity is more prevalent among people with Down Syndrome (DS) compared to general population. In this pilot study, we investigated the effect of cystathionine beta-synthase (CBS) overdosage on the regulation of transsulfuration pathway and the obesity phenotype in fifty adolescents (25 obese/overweight and 25 lean) with trisomy 21.

Methods

The transcriptional levels of CBS in leukocytes and its translational levels in plasma were quantified using real time polymerase chain reaction and enzyme-linked immunosorbent assay respectively. Meanwhile, ultra performance liquid chromatography tandem mass spectrometry was used to determine the plasma concentrations of methionine, homocysteine, cystathionine and cysteine. Fasting plasma lipid profiles were assessed by colorimetric assays. The anthropometric measurements and indices of all subjects were recorded.

Results

Both DS groups had comparable levels of CBS transcripts (p = 0.2734). The plasma levels of the enzyme were significantly higher in the lean DS cases (p = 0.0174) compared to the obese/overweight participants. Total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, methionine, homocysteine, cystathionine and cysteine showed similar plasma levels in both groups. However, the plasma cysteine levels exceeded the normal range in all DS cases. We reported a statistically significant inverse association between CBS enzyme levels and weight (r= - 0.3498, p = 0.0128), hip circumference (r= - 0.3584, p = 0.0106), body mass index (r= - 0.3719, p = 0.0078) and body adiposity index (r= - 0.3183, p = 0.0243).

Conclusions

Our data suggests that the high concentrations of CBS enzyme together with cysteine modulate the DS obesity presumably through increased hydrogen sulfide production which has recently showed anti-adiposity effects.

Fetal alcohol syndrome and the risk of neurodevelopmental disorders: A longitudinal cohort study

BACKGROUND

This hypothesis-testing study evaluated the relationship between fetal alcohol syndrome (FAS) and neurodevelopmental disorder (ND) diagnoses within the Independent Healthcare Research Database (IHRD).

METHODS

De-identified eligibility and claim healthcare records prospectively generated from the 1990-2012 Florida Medicaid system were analyzed using SAS software. There were 89,766 children continuously eligible with ≥10 outpatient office visits during the 120 month period following birth in the cohort examined. A total of 321 children were diagnosed with FAS. Autism spectrum disorder (ASD) (n = 922), tics (n = 551), attention deficit disorder/attention deficit-hyperactivity disorder (ADD/ADHD) (n = 20,260), mental retardation (MR) (n = 915), and specific delays in development (SDD) (n = 24,630) incidence rates were examined using frequency risk ratio (RR) and logistic regression models.

RESULTS

The incidence rate of tics (RR = 5.68), ADD/ADHD (RR = 2.30), MR (RR = 7.83), SDD (RR = 2.88), and ASD (RR = 6.74) were significantly increased among FAS diagnosed children as compared to undiagnosed children. Adjusted (for gender, race, residency, and date of birth) odds ratios (ORs) were significantly increased for tics (OR = 4.87), ADD/ADHD (OR = 3.40), MR (OR = 7.91), SDD (OR = 9.56), and ASD (OR = 6.87) when comparing the FAS diagnosed children to undiagnosed children.

CONCLUSION

Tens of thousands of American children with lifetime costs in the billions of US dollars were estimated to be impacted by FAS-associated NDs. These impacts are particularly tragic because FAS is dependent upon lifestyle.

Childhood MMR Vaccination Effectiveness Against Rubella: A Longitudinal Cohort Study

The vaccine effectiveness (VE) of childhood measles-mumps-rubella (MMR) vaccine to reduce childhood rubella infections in the US during the 1990s/2000s was undertaken in a retrospective longitudinal cohort study. SAS and StatsDirect software were utilized to examine non-identifiable linked eligibility and claim healthcare records prospectively generated from the Florida Medicaid system in the Independent Healthcare Research Database (IHRD). A total of 33 839 children received a single MMR vaccination (vaccinated) and 44 154 children never received a rubella-containing vaccine (unvaccinated) were continuously eligible from 1990 to 2009 for Florida Medicaid within the first 10 years following birth. Cox proportional hazards models determined VE against diagnosed rubella (ICD-9 code: 056.xx). Children receiving MMR were at significantly reduced risk of rubella in unadjusted (VE = 80.7%, 95% confidence interval = 73.7%-85.8%) and adjusted (VE = 78.6%, 95% confidence interval = 70.8%-84.3%) models as compared to unvaccinated children. Between 1991 and 2009, in the combined vaccinated-unvaccinated cohort examined on a yearly basis, a significant inverse correlation between increasing MMR vaccine population coverage and a decreasing incidence rate of diagnosed rubella was observed. This first large-scale population epidemiological study supports the routine use childhood MMR vaccination to significantly reduce childhood rubella infections and also supports its ability to induce “herd immunity.” This study, coupled with a recently published epidemiological study showing childhood MMR vaccination significantly reduced measles infections, provide powerful epidemiological evidence strongly supporting MMR vaccination as an effective tool to improve public health.

How Robust is the Evidence for a Role of Oxidative Stress in Autism Spectrum Disorders and Intellectual Disabilities?

Growing interest in the pathogenesis of autism spectrum disorders (ASDs) and other intellectual and developmental disabilities (IDD) has led to emerging evidence implicating a role for oxidative stress. However, understanding the strength of this association is made challenging by the use of a variety of purported biomarkers of oxidative stress, many of which have either uncertain specificity or flawed methods of analysis. This review aims to address this issue, which is widespread in the ASD and IDD literature, by providing readers with information concerning the strengths and limitations of the choice and analysis of biomarkers of oxidative stress. We highlight that biomarkers and assays should be specific, sensitive, reproducible, precise, robust, and chosen with careful consideration. Future studies should be sufficiently powered and address sample collection, processing, and storage which are, additionally, poorly considered, sources of bad practice, and potential errors. Only with these issues considered, will the data lead to conclusions as to the precise role of oxidative stress in ASDs and IDD.

Abnormalities of synaptic mitochondria in autism spectrum disorder and related neurodevelopmental disorders

Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterized by an impairment of social interaction combined with the occurrence of repetitive behaviors. ASD starts in childhood and prevails across the lifespan. The variability of its clinical presentation renders early diagnosis difficult. Mutations in synaptic genes and alterations of mitochondrial functions are considered important underlying pathogenic factors, but it is obvious that we are far from a comprehensive understanding of ASD pathophysiology. At the synapse, mitochondria perform diverse functions, which are clearly not limited to their classical role as energy providers. Here, we review the current knowledge about mitochondria at the synapse and summarize the mitochondrial disturbances found in mouse models of ASD and other ASD-related neurodevelopmental disorders, like DiGeorge syndrome, Rett syndrome, Tuberous sclerosis complex, and Down syndrome.