Corrigendum: One-carbon pathway metabolites are altered in the plasma of subjects with Down syndrome: relation to chromosomal dosage.

[This corrects the article DOI: 10.3389/fmed.2022.1006891.].

Zinc metabolism and its role in immunity status in subjects with trisomy 21: chromosomal dosage effect.

Introduction: Trisomy 21 (T21), which causes Down syndrome (DS), is the most common chromosomal aneuploidy in humankind and includes different clinical comorbidities, among which the alteration of the immune system has a heavy impact on patient's lives. A molecule with an important role in immune response is zinc and it is known that its concentration is significantly lower in children with T21. Different hypotheses were made about this metabolic alteration and one of the reasons might be the overexpression of superoxide dismutase 1 (SOD1) gene, as zinc is part of the SOD1 active enzymatic center. Methods: The aim of our work is to explore if there is a linear correlation between zinc level and immune cell levels measured in a total of 217 blood samples from subjects with T21. Furthermore, transcriptome map analyses were performed using Transcriptome Mapper (TRAM) software to investigate whether a difference in gene expression is detectable between subjects with T21 and euploid control group in tissues and cells involved in the immune response such as lymphoblastoid cells, thymus and white blood cells. Results: Our results have confirmed the literature data stating that the blood zinc level in subjects with T21 is lower compared to the general population; in addition, we report that the T21/control zinc concentration ratio is 2:3, consistent with a chromosomal dosage effect due to the presence of three copies of chromosome 21. The transcriptome map analyses showed an alteration of some gene's expression which might explain low levels of zinc in the blood. Discussion: Our data suggest that zinc level is not associated with the levels of immunity cells or proteins analyzed themselves and rather the main role of this ion might be played in altering immune cell function.

The functional roles of S-adenosyl-methionine and S-adenosyl-homocysteine and their involvement in trisomy 21.

The one-carbon metabolism pathway is involved in critical human cellular functions such as cell proliferation, mitochondrial respiration, and epigenetic regulation. In the homocysteine-methionine cycle S-adenosyl-methionine (SAM) and S-adenosyl-homocysteine (SAH) are synthetized, and their levels are finely regulated to ensure proper functioning of key enzymes which control cellular growth and differentiation. Here we review the main biological mechanisms involving SAM and SAH and the known related human diseases. It was recently demonstrated that SAM and SAH levels are altered in plasma of subjects with trisomy 21 (T21) but how this metabolic dysregulation influences the clinical manifestation of T21 phenotype has not been previously described. This review aims at providing an overview of the biological mechanisms which are altered in response to changes in the levels of SAM and SAH observed in DS.

One-carbon pathway metabolites are altered in the plasma of subjects with Down syndrome: Relation to chromosomal dosage.

Introduction: Down syndrome (DS) is the most common chromosomal disorder and it is caused by trisomy of chromosome 21 (Hsa21). Subjects with DS show a large heterogeneity of phenotypes and the most constant clinical features present are typical facies and intellectual disability (ID). Several studies demonstrated that trisomy 21 causes an alteration in the metabolic profile, involving among all the one-carbon cycle. Methods: We performed enzyme-linked immunosorbent assays (ELISAs) to identify the concentration of 5 different intermediates of the one-carbon cycle in plasma samples obtained from a total of 164 subjects with DS compared to 54 euploid subjects. We investigated: tetrahydrofolate (THF; DS n = 108, control n = 41), 5-methyltetrahydrofolate (5-methyl-THF; DS n = 140, control n = 34), 5-formyltetrahydrofolate (5-formyl-THF; DS n = 80, control n = 21), S-adenosyl-homocysteine (SAH; DS n = 94, control n = 20) and S-adenosyl-methionine (SAM; DS n = 24, control n = 15). Results: Results highlight specific alterations of THF with a median concentration ratio DS/control of 2:3, a decrease of a necessary molecule perfectly consistent with a chromosomal dosage effect. Moreover, SAM and SAH show a ratio DS/control of 1.82:1 and 3.6:1, respectively. Discussion: The relevance of these results for the biology of intelligence and its impairment in trisomy 21 is discussed, leading to the final proposal of 5-methyl-THF as the best candidate for a clinical trial aimed at restoring the dysregulation of one-carbon cycle in trisomy 21, possibly improving cognitive skills of subjects with DS.

DNA Methylation Analysis of Ribosomal DNA in Adults With Down Syndrome.

Control of ribosome biogenesis is a critical aspect of the regulation of cell metabolism. As ribosomal genes (rDNA) are organized in repeated clusters on chromosomes 13, 14, 15, 21, and 22, trisomy of chromosome 21 confers an excess of rDNA copies to persons with Down syndrome (DS). Previous studies showed an alteration of ribosome biogenesis in children with DS, but the epigenetic regulation of rDNA genes has not been investigated in adults with DS so far. In this study, we used a targeted deep-sequencing approach to measure DNA methylation (DNAm) of rDNA units in whole blood from 69 adults with DS and 95 euploid controls. We further evaluated the expression of the precursor of ribosomal RNAs (RNA45S) in peripheral blood mononuclear cells (PBMCs) from the same subjects. We found that the rDNA promoter tends to be hypermethylated in DS concerning the control group. The analysis of epihaplotypes (the combination of methylated and unmethylated CpG sites along the same DNA molecule) showed a significantly lower intra-individual diversity in the DS group, which at the same time was characterized by a higher interindividual variability. Finally, we showed that RNA45S expression is lower in adults with DS. Collectively, our results suggest a rearrangement of the epigenetic profile of rDNA in DS, possibly to compensate for the extranumerary rDNA copies. Future studies should assess whether the regulation of ribosome biogenesis can contribute to the pathogenesis of DS and explain the clinical heterogeneity characteristic of the syndrome.

A reassessment of Jackson's checklist and identification of two Down syndrome sub-phenotypes.

Down syndrome (DS) is characterised by several clinical features including intellectual disability (ID) and craniofacial dysmorphisms. In 1976, Jackson and coll. identified a checklist of signs for clinical diagnosis of DS; the utility of these checklists in improving the accuracy of clinical diagnosis has been recently reaffirmed, but they have rarely been revised. The purpose of this work is to reassess the characteristic phenotypic signs and their frequencies in 233 DS subjects, following Jackson's checklist. 63.77% of the subjects showed more than 12 signs while none showed less than 5, confirming the effectiveness of Jackson's checklist for the clinical diagnosis of DS. An association between three phenotypic signs emerged, allowing us to distinguish two sub-phenotypes: Brachycephaly, short and broad Hands, short Neck (BHN), which is more frequent, and "non-BHN". The strong association of these signs might be interpreted in the context of the growth defects observed in DS children suggesting decreased cell proliferation. Lastly, cognitive assessments were investigated for 114 subjects. The lack of association between the presence of a physical sign or the number of signs present in a subject and cognitive skills disproves the stereotype that physical characteristics are predictive of degree of ID.

Is the Age of Developmental Milestones a Predictor for Future Development in Down Syndrome?

Down Syndrome (DS) is the most common genetic alteration responsible for intellectual disability, which refers to deficits in both intellectual and adaptive functioning. According to this, individuals with Down Syndrome (DS) reach developmental milestones (e.g., sitting, walking, and babbling) in the same order as their typically developing peers, but later in life. Since developmental milestones are the first blocks on which development builds, the aims of the current study are to: (i) expand the knowledge of developmental milestone acquisition; and (ii) explore the relationship between developmental milestone acquisition and later development. For this purpose 105 children/adolescents with DS were involved in this study, divided in two groups, Preschoolers (n = 39) and School-age participants (n = 66). Information on the age of acquisition of Sitting, Walking, Babbling, and Sphincter Control was collected, together with cognitive, motor, and adaptive functioning. Sitting predicted later motor development, but, with age, it became less important in predicting motor development in everyday life. Babbling predicted later language development in older children. Finally, Sphincter Control emerged as the strongest predictor of motor, cognitive, language, and adaptive skills, with its role being more evident with increasing age. Our data suggest that the age of reaching the milestones considered in the study has an influence on successive development, a role that can be due to common neural substrates, the environment, and the developmental cascade effect.

Accuracy of Lung Ultrasound in Patients with Acute Dyspnea: The Influence of Age, Multimorbidity and Cognitive and Motor Impairment.

Discriminating between causes of dyspnea may be difficult, particularly in the elderly. The aim of this retrospective study of 83 inpatients with acute dyspnea was to assess the influence of age, multimorbidity and cognitive or motor impairment on the diagnostic accuracy of lung ultrasound (LUS) in discriminating acute heart failure (AHF) from noncardiogenic dyspnea (NCD). Univariate analysis indicates that LUS misdiagnosis was associated with the following parameters: history of stroke (p = 0.037), lower activity of daily living (p = 0.039), higher modified-Rankin scale (mRS) (p = 0.027) and need of two operators to complete LUS because of reduced patient compliance (p = 0.030). Regression analysis identified only history of stroke (p = 0.048) as an independent predictor of LUS misdiagnosis. This study supports LUS usefulness to differentiate AHF from NCD. Our data suggest that diagnostic accuracy of LUS is affected by history of stroke as a proxy for severe motor impairment but not by age, cognitive impairment and multimorbidity.

Homocysteinemia and early outcome of acute ischemic stroke in elderly patients.

OBJECTIVES: Plasma total homocysteine (tHcy) is a risk factor for ischemic stroke (IS) but its relationship with IS outcome is uncertain. Moreover, previous studies underrepresented older IS patients, although risk of both hyperhomocysteinemia and IS increases with age. We investigated whether, in elderly patients with acute IS, tHcy measured on admission to the Stroke Unit (SU) is an independent predictor of SU discharge outcomes. MATERIALS AND METHODS: Data are for 644 consecutive patients aged 80.3 ± 8.7 years, admitted to an Italian SU with diagnosis of acute IS. Plasma tHcy was measured on SU admission. Investigated outcomes included mortality during SU stay and poor functional status (modified Rankin Scale score ≥3) at SU discharge for survivors. The association of plasma tHcy with the study outcomes was assessed using Odds Ratios (OR) and their corresponding 95% confidence intervals (95%CI) from logistic regression models adjusted for demographics, pre-stroke features, IS severity, and laboratory data on SU admission (serum C-reactive protein, serum albumin, and renal function). RESULTS: Median plasma tHcy was 16.7 µmol/L (interquartile range, 13.0-23.3 µmol/L). Outcome incidence was 5.3% for mortality and 49.7% for poor functional status. Plasma tHcy was unrelated to mortality in both univariate and multivariable-adjusted analyses. Conversely, plasma tHcy was associated with poor functional status of survivors in univariate analyses (P = 0.014). Multivariable-adjusted analyses showed that, compared to normal homocysteinemia (tHcy <16 µmol/L), risk of being discharged with poor functional status significantly increased for moderate (tHcy ≥30 mol/L) but not mild (16.0-29.9 µmol/L) hyperhomocysteinemia. CONCLUSIONS: In elderly patients with acute IS, high admission plasma tHcy is unrelated to mortality during SU stay but is an independent predictor of poor functional status at SU discharge in survivors. The association, however, is limited to patients with moderate hyperhomocysteinemia.

Serum dehydroepiandrosterone sulfate and adverse health outcomes in older men and women.

Low serum dehydroepiandrosterone sulfate (DHEAS) is common in older persons with poor health. The geriatric syndrome of physical frailty is associated with a higher risk of developing fatal and nonfatal health outcomes. However, the association of DHEAS with frailty is uncertain. This study investigated the association of serum DHEAS with frailty and its related adverse outcomes in 416 men and 504 women aged ≥65 years from an Italian prospective population-based cohort study. At baseline, frailty status was defined according to the physical phenotype, and serum DHEAS was measured in a fasting venous blood sample. After 4 years, subjects were reassessed for incident frailty and occurrence of nonfatal frailty-related outcomes (hospital admission, nursing home placement, disability, falls, and fractures). All-cause mortality after 8 years was also recorded. Incident frailty was inversely associated with baseline log-transformed DHEAS in men (odds ratio [OR]=0.35, 95% confidence interval [CI] 0.14-0.88, p=0.026) but not in women. Independent of baseline frailty status, women in the lowest DHEAS quartile compared to the upper three quartiles had a higher risk of hospital admission (OR=0.44, 95% CI 0.21-0.91, p=0.027) and nursing home placement (OR=0.27, 95% CI 0.08-0.95, p=0.041). Baseline log-transformed serum DHEAS was also inversely associated with mortality risk, but limited to women with concurrent frailty (hazard ratio [HR]=0.27, 95% CI 0.11-0.68, p=0.005) or preexisting major diseases (HR=0.57, 95% CI 0.33-0.98, p=0.041). These findings suggest that DHEAS is associated with incident frailty in older men and with fatal and nonfatal frailty-related adverse outcomes in older women.