Sleep onset insomnia, daytime sleepiness and sleep duration in relationship to Toxoplasma gondii IgG seropositivity and serointensity.

Toxoplasma gondii (T. gondii) infects central nervous tissue and is kept in relative dormancy by a healthy immune system. Sleep disturbances have been found to precipitate mental illness, suicidal behavior and car accidents, which have been previously linked to T. gondii as well. We speculated that if sleep disruption, particularly insomnia, would mediate, at least partly, the link between T. gondii infection and related behavioral dysregulation, then we would be able to identify significant associations between sleep disruption and T. gondii. The mechanisms for such an association may involve dopamine (DA) production by T. gondii, or collateral effects of immune activation necessary to keep T. gondii in check. Sleep questionnaires from 2031 Old Order Amish were analyzed in relationship to T. gondii-IgG antibodies measured by enzyme-linked immunosorbent assay (ELISA). Toxoplasma gondii seropositivity and serointensity were not associated with any of the sleep latency variables or Epworth Sleepiness Scale (ESS). A secondary analysis identified, after adjustment for age group, a statistical trend toward shorter sleep duration in seropositive men (p = 0.07). In conclusion, it is unlikely that sleep disruption mediates links between T. gondii and mental illness or behavioral dysregulation. Trending gender differences in associations between T. gondii and shorter sleep need further investigation.

Heritability of plasma neopterin levels in the Old Order Amish.

BACKGROUND: We examined the heritability of neopterin, a biomarker for cell-mediated immunity and oxidative stress, and potentially for psychiatric disorders, in the Old Order Amish. METHODS: Plasma neopterin levels were determined in 2015 Old Order Amish adults. Quantitative genetic procedures were used to estimate heritability of neopterin. RESULTS: Heritability of log-neopterin was estimated at 0.07 after adjusting for age, gender, and household (p=0.03). The shared household effect was 0.06 (p<0.02). CONCLUSIONS: We found a low heritability of neopterin and small household effect, suggesting that non-household environmental factors are more important determinants of variance of neopterin levels in the Amish.

From Genotype to Phenotype: Nonsense Variants in SLC13A1 Are Associated with Decreased Serum Sulfate and Increased Serum Aminotransferases.

Using genomic applications to glean insights into human biology, we systematically searched for nonsense single nucleotide variants (SNVs) that are rare in the general population but enriched in the Old Order Amish (Amish) due to founder effect. We identified two nonlinked, nonsense SNVs (R12X and W48X) in SLC13A1 (allele frequencies 0.29% and 0.74% in the Amish; enriched 1.2-fold and 3.7-fold, compared to the outbred Caucasian population, respectively). SLC13A1 encodes the apical sodium-sulfate cotransporter (NaS1) responsible for sulfate (re)absorption in the kidneys and intestine. SLC13A1 R12X and W48X were independently associated with a 27.6% (P = 2.7 × 10(-8)) and 27.3% (P = 6.9 × 10(-14)) decrease in serum sulfate, respectively (P = 8.8 × 10(-20) for carriers of either SLC13A1 nonsense SNV). We further performed the first exome- and genome-wide association study (ExWAS/GWAS) of serum sulfate and identified a missense variant (L348P) in SLC26A1, which encodes the basolateral sulfate-anion transporter (Sat1), that was associated with decreased serum sulfate (P = 4.4 × 10(-12)). Consistent with sulfate's role in xenobiotic detoxification and protection against acetaminophen-induced hepatotoxicity, SLC13A1 nonsense SNV carriers had higher aminotransferase levels compared to noncarriers. Furthermore, SLC26A1 L348P was associated with lower whole-body bone mineral density (BMD) and higher serum calcium, consistent with the osteochondrodysplasia exhibited by dogs and sheep with naturally occurring, homozygous, loss-of-function mutations in Slc13a1 This study demonstrates the power and translational potential of systematic identification and characterization of rare, loss-of-function variants and warrants additional studies to better understand the importance of sulfate in human physiology, disease, and drug toxicity.

Genetic Variation in the Platelet Endothelial Aggregation Receptor 1 Gene Results in Endothelial Dysfunction.

Platelet Endothelial Aggregation Receptor 1 (PEAR1) is a newly identified membrane protein reported to be involved in multiple vascular and thrombotic processes. While most studies to date have focused on the effects of this receptor in platelets, PEAR1 is located in multiple tissues including the endothelium, where it is most highly expressed. Our first objective was to evaluate the role of PEAR1 in endothelial function by examining flow-mediated dilation of the brachial artery in 641 participants from the Heredity and Phenotype Intervention Heart Study. Our second objective was to further define the impact of PEAR1 on cardiovascular disease computationally through meta-analysis of 75,000 microarrays, yielding insights regarding PEAR1 function, and predictions of phenotypes and diseases affected by PEAR1 dysregulation. Based on the results of this meta-analysis we examined whether genetic variation in PEAR1 influences endothelial function using an ex vivo assay of endothelial cell migration. We observed a significant association between rs12041331 and flow-mediated dilation in participants of the Heredity and Phenotype Intervention Heart Study (P = 0.02). Meta-analysis results revealed that PEAR1 expression is highly correlated with several genes (e.g. ANG2, ACVRL1, ENG) and phenotypes (e.g. endothelial cell migration, angiogenesis) that are integral to endothelial function. Functional validation of these results revealed that PEAR1 rs12041331 is significantly associated with endothelial migration (P = 0.04). Our results suggest for the first time that genetic variation of PEAR1 is a significant determinant of endothelial function through pathways implicated in cardiovascular disease.