Assessment of haptoglobin alleles in autism spectrum disorders

Haptoglobin Gene Expression and Anthracycline-Related Cardiomyopathy in Childhood Cancer Survivors: A COG-ALTE03N1 Report

Background

Anthracycline-related cardiomyopathy is a leading cause of premature death in childhood cancer survivors. The high interindividual variability in risk suggests the need to understand the underlying pathogenesis.

Objectives

The authors interrogated differentially expressed genes (DEGs) to identify genetic variants serving regulatory functions or genetic variants not easily identified when using genomewide array platforms. Using leads from DEGs, candidate copy number variants (CNVs) and single-nucleotide variants (SNVs) were genotyped.

Methods

Messenger RNA sequencing was performed on total RNA from peripheral blood of 40 survivors with cardiomyopathy (cases) and 64 matched survivors without cardiomyopathy (control subjects). Conditional logistic regression analysis adjusting for sex, age at cancer diagnosis, anthracycline dose, and chest radiation was used to assess the associations between gene expression and cardiomyopathy and between CNVs and SNVs and cardiomyopathy.

Results

Haptoglobin (HP) was identified as the top DEG. Participants with higher HP gene expression had 6-fold greater odds of developing cardiomyopathy (OR: 6.4; 95% CI: 1.4-28.6). The HP2-specific allele among the HP genotypes (HP1-1, HP1-2, and HP2-2) had higher transcript levels, as did the G allele among SNVs previously reported to be associated with HP gene expression (rs35283911 and rs2000999). The HP1-2 and HP2-2 genotypes combined with the G/G genotype for rs35283911 and/or rs2000999 placed the survivors at 4-fold greater risk (OR: 3.9; 95% CI: 1.0-14.5) for developing cardiomyopathy.

Conclusions

These findings provide evidence of a novel association between HP2 allele and cardiomyopathy. HP binds to free hemoglobin to form an HP-hemoglobin complex, thereby preventing oxidative damage from free heme iron, thus providing biological plausibility to the mechanistic basis of the present observation.

Serum Zonulin Levels Are Higher Among Children with Autism Spectrum Disorders and Correlated with Social Impairment

OBJECTIVE

Zonulin is a protein that affects the integrity of intercellular connections in the intestines. It has been emphasized that autoimmune diseases as well as neurodevelopmental disorders, for example autism spectrum disorder (ASD), may occur through alterations in intestinal permeability and blood-brain barrier. We aimed to investigate the gastrointestinal permeability of individuals with ASD by determining serum zonulin levels and their relationship to symptom severity.

METHODS

Twenty-five ASD patients and 19 controls were included. Serum zonulin levels were measured by enzyme-linked immunosorbent assay kits. Clinical severity was assessed by the Childhood Autism Rating Scale (CARS), and social skills of the control group were evaluated by the Conners' Parents and Teacher's Rating Scales-Revised/Long Forms (CPRS-CTRS).

RESULTS

Mean zonulin levels were significantly higher in the ASD group and positively correlated with CARS scores. After regression analysis, serum zonulin levels predicted CARS total scores. We could not find any significant correlation between zonulin levels and CPRS-CTRS sociability subscale scores in the control group.

CONCLUSION

The positive correlation between serum zonulin levels and ASD severity may require precaution for impaired intestinal permeability in clinical practice, especially for the cases in which sociability is severely impaired. However, it is too early to state that intestinal permeability has a role in the etiology of ASD. Further studies involving specific autism subgroups, and samples with certain dietary differences are needed.

Haptoglobin polymorphisms in Latin American populations

Several genetic polymorphisms of the haptoglobin gene (HP) or haptoglobin-related gene (HPR) were reported to show a population-specific distribution and to be associated with not only serum haptoglobin (HP) but also cholesterol levels. For such association studies, it is important to know the distribution of polymorphisms or their haplotypes in the populations concerned. However, no comprehensive genetic studies have explored this in Latin Americans, and not every human variation or genotype is available in a database. In this study, we determined the genotypes of common HP (HP¹ and HP²), HP^del, rs5471, rs5472, and rs2000999 in several Latin American populations. Haplotypes of rs5472-common HP-rs2000999 polymorphisms were estimated. We did not encounter any HP^del, and the frequencies of rs5471 A, rs5472 A, HP¹, and rs2000999 G were higher than their counterpart alleles in studied populations. All of the alleles with higher frequency in the Latin Americans are associated with higher serum HP and lower cholesterol levels. Both A-1-G (probably HP^1S) and G-1-G (probably HP^1F) haplotypes were higher in Latin American populations than those in other geographic regions. In addition, the genetic influx from populations of other continents into Peruvians seems to be relatively lower than that into other Latin Americans.