Sunday M. Francis

Oxytocin and vasopressin systems in genetic syndromes and neurodevelopmental disorders

Oxytocin (OT) and arginine vasopressin (AVP) are two small, related neuropeptide hormones found in many mammalian species, including humans. Dysregulation of these neuropeptides have been associated with changes in behavior, especially social interactions. We review how the OT and AVP systems have been investigated in Autism Spectrum Disorder (ASD), Prader-Willi Syndrome (PWS), Williams Syndrome (WS) and Fragile X syndrome (FXS). All of these neurodevelopmental disorders (NDD) are marked by social deficits. While PWS, WS and FXS have identified genetic mutations, ASD stems from multiple genes with complex interactions. Animal models of NDD are invaluable for studying the role and relatedness of OT and AVP in the developing brain. We present data from a FXS mouse model affecting the fragile X mental retardation 1 (Fmr1) gene, resulting in decreased OT and AVP staining cells in some brain regions. Reviewing the research about OT and AVP in these NDD suggests that altered OT pathways may be downstream from different etiological factors and perturbations in development. This has implications for ongoing studies of the therapeutic application of OT in NDD. This article is part of a Special Issue entitled Oxytocin and Social Behav.

Rare Inherited A2BP1 Deletion In A Proband With Autism And Developmental Hemiparesis

Ataxin 2 binding protein 1 (A2BP1 aka FOX1, RBFOX1) is an RNA binding protein responsible for regulation of pre‐mRNA splicing events in a number of critical developmental genes expressed in muscle, heart and neuronal cells [Shibata et al. (2000); Mamm Genome 12:595–601; Jin et al. (2003); EMBO J 22:905–912; Underwood et al. (2005); Mol Cell Biol 25:10005–10016]. Rare copy number abnormalities of A2BP1 have been previously associated with cognitive impairment, attention deficit disorder and autism [Martin et al. (2007); Am J Med Gen Part B 144B:869–876; Elia et al. (2010); Mol Psychiatry 15:637–646.]. Using a 1M Illumina SNP microarray, we identified a 1.3 kb deletion in A2BP1, which was subsequently validated by quantitative PCR. Here we present an in depth case study of an individual with autism and mild developmental hemiparesis in whom the deletion was detected. This study provides further support for the possible role of rare copy number variants in A2BP1 in the development of autism and associated motor asymmetries.

A Deletion Involving CD38 and BST1 Results in a Fusion Transcript in a Patient With Autism and Asthma

CD38 encodes a ligand in the oxytocin signaling pathway. Some single nucleotide polymorphisms in this gene have been associated with low serum oxytocin levels in autism spectrum disorder (ASD) patients. Oxytocin disruption has been hypothesized to account for features of ASD, including impaired communication and social behavior, based on animal studies. Recent human studies have shown administration of oxytocin improving emotion recognition, promoting social behavior, and improving auditory processing of social stimuli in ASD patients. In addition to its role in oxytocin signaling, CD38 is involved in the regulation of calcium concentration in airway smooth muscle with impairment of CD38 being implicated in airway diseases like asthma. While a number of studies have implicated rare chromosomal deletions and duplications in helping determine genetic risk for autism, there are to our knowledge no reports describing rearrangements involving CD38 or deletions in patients with ASD. Here, we present two sisters diagnosed with autism and with features of regression—previously acquired speech lost in the second year of life. The younger sister, who also had asthma, inherited a maternal deletion of 4p15.32 that results in a BST1‐CD38 fusion transcript. Their mothers deletion was mosaic and she was not affected. Although further work is required to assess functional consequences of the fusion transcript, we hypothesize that the probands deletion may have served as a risk factor for autism that, when combined with other susceptibility variants, resulted in a more severe presentation than her sister. Autism Res 2014, 7: 254–263.

Urinary and plasma oxytocin changes in response to MDMA or intranasal oxytocin administration

BACKGROUND The neuropeptide oxytocin (OT) has received increased experimental attention for its putative role in both normal social functioning and several psychiatric disorders that are partially characterized by social dysfunction (e.g., autism spectrum disorders: ASD). Many human experimental studies measure circulating plasma levels of OT in order to examine the relationship between the hormone and behavior. Urinary OT (uOT) assays offer a simple, easy, and non-invasive method to measure peripheral hormone levels, but the correspondence between uOT and plasma OT (pOT) levels is unclear. Here, we conducted two within-subjects, double-blind studies exploring changes in uOT and pOT levels following administration of two drugs: MDMA, an oxytocin-releasing drug (Study 1), and intranasal oxytocin (INOT: Study 1 and 2). METHODS In Study 1, 14 adult participants (2 females) were each administered either oral 1.5mg/kg MDMA or 40IU INOT across two different study sessions. In Study 2, 10 male participants (adolescents and young adults) diagnosed with ASD received either 40IU INOT or placebo across two different sessions. In both studies, blood and urine samples were collected before and after drug administration at each study session. For Study 1, 10 participants provided valid plasma and urine samples for the MDMA session, and 8 provided valid samples for the INOT session. For Study 2, all 10 participants provided valid samples for both INOT and placebo sessions. Pre- and post-administration levels of pOT and uOT were compared. Additionally, correlations between percent change from baseline uOT and pOT levels were examined. RESULTS Study 1: Plasma OT and uOT levels significantly increased after administration of MDMA and INOT. Furthermore, uOT levels were positively correlated with pOT levels following administration of MDMA (r=0.57, p=0.042) but not INOT (r=0.51, p=0.097). Study 2: There was a significant increase in uOT levels after administration of INOT, but not after administration of placebo. Under both conditions, INOT and placebo, significant increases in pOT levels were not observed. Additionally, change from baseline uOT and pOT levels were positively correlated (r=0.57, p=0.021). There was no significant correlation between uOT and pOT levels following placebo administration. CONCLUSION Our results show a measurable and significant increase in pOT and uOT levels after the administration of MDMA (Study 1) and INOT (Study 1 and Study 2). Additionally, a positive correlation between uOT and pOT levels was observed in both samples (healthy adults and ASD patients) in at least one condition. However, uOT and pOT levels were not correlated under all conditions, suggesting that uOT levels do not fully correspond to pOT levels in the time windows we measured. Future studies should further examine the relationship between levels of pOT and uOT in healthy and clinical populations on measures of social behavior because uOT may serve as an additional non-invasive method to measure peripheral OT changes.

ASD and genetic associations with receptors for oxytocin and vasopressin-AVPR1A, AVPR1B, and OXTR

Background: There are limited treatments available for autism spectrum disorder (ASD). Studies have reported significant associations between the receptor genes of oxytocin (OT) and vasopressin (AVP) and ASD diagnosis, as well as ASD-related phenotypes. Researchers have also found the manipulation of these systems affects social and repetitive behaviors, core characteristics of ASD. Consequently, research involving the oxytocin/vasopressin pathways as intervention targets has increased. Therefore, further examination into the relationship between these neuropeptides and ASD was undertaken. In this study, we examined associations between variants in the receptor genes of vasopressin (AVPR1A, AVPR1B), oxytocin (OXTR), and ASD diagnosis along with related subphenotypes. Methods: Probands were assessed using Autism Diagnostic Interview-Revised, Autism Diagnostic Observation Schedule, and clinical DSM-IV-TR criteria. Single nucleotide polymorphisms (SNPs) in AVPR1B and OXTR, and microsatellites in AVPR1A were genotyped in ~200 families with a proband with ASD. Family-based association testing (FBAT) was utilized to determine associations between variants and ASD. Haplotypes composed of OXTR SNPs (i.e., rs53576-rs2254298-rs2268493) were also analyzed due to previously published associations. Results: Using the additive inheritance model in FBAT we found associations between AVPR1B SNPs (rs28632197, p = 0.005, rs35369693, p = 0.025) and diagnosis. As in other studies, OXTR rs2268493 (p = 0.050) was associated with diagnosis. rs2268493 was also associated with ASD subphenotypes of social withdrawal (p = 0.013) and Insistence on Sameness (p = 0.039). Further analyses demonstrated that the haplotype, rs2254298–rs2268493 was found to be significantly associated with diagnosis (A-T; p = 0.026). FBAT was also used to analyze AVPR1A microsatellites (RS1 and RS3). Both length variants were found to be associated with restrictive, repetitive behaviors, but not overall diagnosis. Correction for multiple comparisons was performed for SNPs tested in each gene region, only AVPR1B SNPs remained significantly associated with ASD diagnosis. Conclusions: Autism is a heterogeneous disorder with many genes and pathways that contribute to its development. SNPs and microsatellites in the receptor genes of OT and AVP are associated with ASD diagnosis and measures of social behavior as well as restricted repetitive behaviors. We reported a novel association with ASD and AVPR1B SNPs. Understanding of genotype-phenotype relationships may be helpful in the development of pharmacological interventions for the OT/AVP system.

Parental Broader Autism Subphenotypes in ASD Affected Families: Relationship to Gender, Child's Symptoms, SSRI Treatment, and Platelet Serotonin

Relationships between parental broader autism phenotype (BAP) scores, gender, selective serotonin reuptake inhibitor (SSRI) treatment, serotonin (5HT) levels, and the childs symptoms were investigated in a family study of autism spectrum disorder (ASD). The Broader Autism Phenotype Questionnaire (BAPQ) was used to measure the BAP of 275 parents. Fathers not taking SSRIs (F‐SSRI; n = 115) scored significantly higher on BAP Total and Aloof subscales compared to mothers not receiving treatment (M‐SSRI; n = 136.) However, mothers taking SSRIs (M + SSRI; n = 19) scored higher than those not taking medication on BAP Total and Rigid subscales, and they were more likely to be BAPQ Total, Aloof, and Rigid positive. Significant correlations were noted between proband autism symptoms and parental BAPQ scores such that Total, Aloof, and Rigid subscale scores of F‐SSRI correlated with proband restricted repetitive behavior (RRB) measures on the ADOS, CRI, and RBS‐R. However, only the Aloof subscale score of M + SSRI correlated with proband RRB on the ADOS. The correlation between the BAPQ scores of mothers taking SSRIs and child scores, as well as the increase in BAPQ scores of this group of mothers, requires careful interpretation and further study because correlations would not withstand multiple corrections. As expected by previous research, significant parent–child correlations were observed for 5HT levels. However, 5HT levels were not correlated with behavioral measures. Study results suggest that the expression of the BAP varies not only across parental gender, but also across individuals using psychotropic medication and those who do not. Autism Res 2013, 6: 621–630.

Variants in Adjacent Oxytocin/Vasopressin Gene Region and Associations with ASD Diagnosis and Other Autism Related Endophenotypes

Background: There has been increasing interest in oxytocin (peptide: OT, gene: OXT) as a treatment pathway for neurodevelopmental disorders such as Autism Spectrum Disorder (ASD). Neurodevelopmental disorders affect functional, social, and intellectual abilities. With advances in molecular biology, research has connected multiple gene regions to the clinical presentation of ASD. Studies have also shown that the neuropeptide hormones OT and arginine vasopressin (AVP) influence mammalian social and territorial behaviors and may have treatment potential for neurodevelopmental disorders. Published data examining molecular and phenotypic variation in ASD, such as cognitive abilities, are limited. Since most studies have focused on the receptors in the OT-AVP system, we investigated genetic variation within peptide genes for association with phenotypic ASD features that help identify subgroups within the spectrum. Methods: In this study, TDT analysis was carried out utilizing FBAT in 207 probands (156 trios) and a European Ancestry (EA) subsample (108 trios).The evolutionarily related and adjacent genes of OXT and AVP were studied for associations between the tagged single nucleotide polymorphisms and ASD diagnosis, social abilities, restrictive and repetitive behaviors, and IQ for cognitive abilities. Additionally, relationships with whole blood serotonin (WB5HT) were explored because of the developmental relationships connecting plasma levels of OT and WB5HT within ASD. Results: Results indicate significant association between OXT rs6084258 (p = 0.001) and ASD. Associations with several endophenotypes were also noted: OXT rs6133010 was associated with IQ (full scale IQ, p = 0.008; nonverbal IQ, p = 0.010, verbal IQ, p = 0.006); and OXT rs4813625 and OXT rs877172 were associated with WB5HT levels (EA, p = 0.027 and p = 0.033, respectively). Additionally, we measured plasma OT (pOT) levels in a subsample (N = 54). Results show the three polymorphisms, OXT rs6084258, OXT rs11697250, and OXT rs877172, have significant association with pOT (EA, p = 0.011, p = 0.010, and p = 0.002, respectively). Conclusions: These findings suggest that SNPs near OXT and AVP are associated with diagnosis of ASD, social behaviors, restricted and repetitive behaviors, IQ, pOT, and WB5HT. Future studies need to replicate these findings and examine gene-interactions in other neurodevelopmental disorders. Mechanisms of action may influence early social and cognitive development that may or may not be limited to ASD diagnosis.

Oxytocin and Vasopressin in Autism and Genetic Syndromes

Oxytocin (OT) and arginine vasopressin (AVP) are two small, related neuropeptides found in many mammalian species, including humans. These neuropeptides are associated with a range of social behaviors and their dysregulation has been associated with deficits in social behavior. In particular, the OT neuropeptide system has been investigated in Autism Spectrum Disorder (ASD), as well as in Prader-Willi Syndrome (PWS), Williams Syndrome (WS) and Fragile X Syndrome (FXS), all of which are characterized by marked social deficits. PWS, WS and FXS are caused by identified genetic mutations and provide insight into the developmental influences of the OT system. In particular, FXS is caused by a mutation in a single gene and up to 47 % of patients with FXS are diagnosed with ASD or also have autism related behaviors. Animal models of genetic neurodevelopmental disorders (NDD) are becoming a valuable tool to examine the role and relatedness of OT and AVP in the developing brain. We provide an example of how OT and AVP systems are altered with a mutation in the mouse Fragile X mental retardation 1 (Fmr1) gene which leads to FXS-like symptoms in Fmr1 knockout (KO) mice. By studying the OT and AVP systems in these rare disorders, we may further understand their mechanisms of action in ASD and in typical development. This chapter will summarize the current data pertaining to these NDD and the systems of OT and AVP.