Escitalopram pharmacogenetics: CYP2C19 relationships with dosing and clinical outcomes in autism spectrum disorder.

BACKGROUND AND AIM: Selective serotonin reuptake inhibitors such as escitalopram are commonly used to treat patients with autism spectrum disorder (ASD), but there are individual differences in treatment response and tolerability. CYP2C19 encodes the primary enzyme responsible for escitalopram metabolism and we investigated whether polymorphisms in CYP2C19 were related to symptoms and dosing in a pharmacogenetic study of ASD. PARTICIPANTS AND METHODS: Participants completed the Aberrant Behavior Checklist--Community Version (ABC-CV) weekly for 6 weeks. Escitalopram was initiated at a dose of 2.5 mg per day, with weekly increases to 20 mg unless intolerable side-effects occurred. Three CYP2C19 metabolizer groups, including ultrarapid, extensive, and reduced metabolizers, were examined in relation to symptom improvement and tolerated dose. RESULTS: ABC-CV scores improved over the course of treatment (P<0.0001). No differences were identified in the rate of improvement across metabolizer groups for the ABC-CV irritability subscale, which was the primary outcome for clinical symptoms. There was a trend for a metabolizer group by time interaction with respect to dose (P=0.10). This interaction was driven by the linear rate of change from week 1 to study endpoint between the reduced metabolizers and ultrarapid metabolizer groups (P=0.05). Post-hoc analyses identified significant differences in the rate of dose escalation between ultrarapid metabolizers and extensive metabolizers and for ultrarapid metabolizers compared with reduced metabolizers (P's<0.04), whereby ultrarapid metabolizers showed a slower rate of change in dose over time. CONCLUSION: CYP2C19 ultrarapid metabolizers were associated with reduced tolerance to a fixed titration schedule of open-label escitalopram in this ASD study sample. Possible explanations may involve the altered kinetics of faster metabolizers or previously unknown activities of escitalopram metabolites.

Common genetic variants on 5p14.1 associate with autism spectrum disorders.

Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)-two genes encoding neuronal cell-adhesion molecules-revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4 x 10(-8), odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined P values ranging from 7.4 x 10(-8) to 2.1 x 10(-10). Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.

Autism genome-wide copy number variation reveals ubiquitin and neuronal genes.

Autism spectrum disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins. Previous studies focusing on candidate genes or genomic regions have identified several copy number variations (CNVs) that are associated with an increased risk of ASDs. Here we present the results from a whole-genome CNV study on a cohort of 859 ASD cases and 1,409 healthy children of European ancestry who were genotyped with approximately 550,000 single nucleotide polymorphism markers, in an attempt to comprehensively identify CNVs conferring susceptibility to ASDs. Positive findings were evaluated in an independent cohort of 1,336 ASD cases and 1,110 controls of European ancestry. Besides previously reported ASD candidate genes, such as NRXN1 (ref. 10) and CNTN4 (refs 11, 12), several new susceptibility genes encoding neuronal cell-adhesion molecules, including NLGN1 and ASTN2, were enriched with CNVs in ASD cases compared to controls (P = 9.5 x 10(-3)). Furthermore, CNVs within or surrounding genes involved in the ubiquitin pathways, including UBE3A, PARK2, RFWD2 and FBXO40, were affected by CNVs not observed in controls (P = 3.3 x 10(-3)). We also identified duplications 55 kilobases upstream of complementary DNA AK123120 (P = 3.6 x 10(-6)). Although these variants may be individually rare, they target genes involved in neuronal cell-adhesion or ubiquitin degradation, indicating that these two important gene networks expressed within the central nervous system may contribute to the genetic susceptibility of ASD.

Genome-wide analyses of exonic copy number variants in a family-based study point to novel autism susceptibility genes.

The genetics underlying the autism spectrum disorders (ASDs) is complex and remains poorly understood. Previous work has demonstrated an important role for structural variation in a subset of cases, but has lacked the resolution necessary to move beyond detection of large regions of potential interest to identification of individual genes. To pinpoint genes likely to contribute to ASD etiology, we performed high density genotyping in 912 multiplex families from the Autism Genetics Resource Exchange (AGRE) collection and contrasted results to those obtained for 1,488 healthy controls. Through prioritization of exonic deletions (eDels), exonic duplications (eDups), and whole gene duplication events (gDups), we identified more than 150 loci harboring rare variants in multiple unrelated probands, but no controls. Importantly, 27 of these were confirmed on examination of an independent replication cohort comprised of 859 cases and an additional 1,051 controls. Rare variants at known loci, including exonic deletions at NRXN1 and whole gene duplications encompassing UBE3A and several other genes in the 15q11-q13 region, were observed in the course of these analyses. Strong support was likewise observed for previously unreported genes such as BZRAP1, an adaptor molecule known to regulate synaptic transmission, with eDels or eDups observed in twelve unrelated cases but no controls (p = 2.3x10(-5)). Less is known about MDGA2, likewise observed to be case-specific (p = 1.3x10(-4)). But, it is notable that the encoded protein shows an unexpectedly high similarity to Contactin 4 (BLAST E-value = 3x10(-39)), which has also been linked to disease. That hundreds of distinct rare variants were each seen only once further highlights complexity in the ASDs and points to the continued need for larger cohorts.

The SOFIA Study: Negative Multi-center Study of Low Dose Fluoxetine on Repetitive Behaviors in Children and Adolescents with Autistic Disorder.

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that reduces obsessive-compulsive symptoms. There is limited evidence supporting its efficacy for repetitive behaviors (RRBs) in autistic spectrum disorder (ASD). We conducted a randomized controlled trial (RCT) of fluoxetine in 158 individuals with ASD (5-17 years). Following 14 treatment weeks (mean dose 11.8 mg/day), no significant differences were noted on the Children's Yale-Brown Obsessive Compulsive Scale; the proportion of responders was similar (fluoxetine: 36%; placebo: 41%). There were similar rates of AEs (e.g., insomnia, diarrhea, vomiting); high rates of activation were reported in both groups (fluoxetine: 42%; placebo: 45%). Overly cautious dosing/duration may have prevented attainment of a therapeutic level. Results are consistent with other SSRI RCTs treating RRBs in ASD.Trial Registration: clinicaltrials.gov Identifier: NCT00515320.

A prospective, open-label trial of memantine in the treatment of cognitive, behavioral, and memory dysfunction in pervasive developmental disorders.

BACKGROUND: This pilot study examined the effectiveness of memantine hydrochloride in improving cognitive functioning and behavioral symptoms in children with pervasive developmental disorders (PDDs). METHOD: Subjects aged 3-12 years inclusive were enrolled in this 8-week, open-label study. Expressive and receptive language, nonverbal IQ, and nonverbal memory measures were administered at baseline and after 8 weeks of treatment with 0.4 mg/kg of memantine hydrochloride. Throughout the study, the Aberrant Behavior Checklist (ABC) was sent in weekly by parents as a measure of behavioral change. RESULTS: Twelve of 14 subjects completed the study. Significant improvement from baseline was noted on the memory test (Children's Memory Scale Dot Learning Subtest). There were no significant differences from baseline on measures of expressive or receptive language or nonverbal IQ. There were significant improvements on a number of ABC subscales, including hyperactivity, lethargy, and irritability. There were no overall significant statistical differences from baseline on the Clinical Global Improvement-Severity (CGI-S) scale. On the Clinical Global Improvement-Improvement (CGI-I), 4 of 14 subjects showed minimal improvement, and none was deemed "much-improved" or "very much improved." CONCLUSIONS: This small, prospective, open-label study suggests that memantine may be useful in the treatment of memory functioning and some behavioral symptoms in PDDs. The investigators did not see the same degree of change as endorsed by caretakers. Controlled studies are needed to substantiate and clarify these preliminary findings.

An open-label trial of escitalopram in pervasive developmental disorders.

OBJECTIVE: To assess the effect of escitalopram in the treatment of pervasive developmental disorders (PDDs). METHOD: This 10-week study had a forced titration, open-label design. Twenty-eight subjects (mean age 125.1 +/- 33.5 months) with a PDD received escitalopram at a dose that increased weekly to a maximum dose of 20 mg as tolerated. The Aberrant Behavior Checklist-Community Version (ABC-CV) and the Clinical Global Impression scale (CGI) were used to assess outcome. RESULTS: There was significant improvement in ABC-CV Irritability Subscale Scores (baseline mean 20.5 +/- 5.9 to final mean 10.9 +/- 7.2; p < or = .001) and in the other ABC-CV Subscales. Improvement on Clinical Global Improvement Scale severity rating was also significant (baseline mean 5.2 +/- 1.0 to final mean 4.6 +/- 1.2; p < or = .001). Twenty-five percent of the subjects responded at a dose less than 10 mg and did not tolerate the 10-mg dose, and an additional 36% responded at a dose greater than or equal to 10 mg. Final dose was unrelated to weight and only weakly correlated with age. CONCLUSIONS: This open-label study found escitalopram to be useful in treating some difficulties common in PDDs. A wide variability in dose was found that could not be accounted for by weight and only partially by age. The study provides information useful for the design of double-blind, placebo-controlled studies of escitalopram in PDDs.

Pharmacogenetic Study of Serotonin Transporter and 5HT2A Genotypes in Autism.

OBJECTIVE: The purpose of this study was to determine whether polymorphisms in the serotonin transporter (SLC6A4) and serotonin-2A receptor (HTR2A) genes are associated with response to escitalopram in patients with autism spectrum disorder (ASD). METHODS: Forty-four participants with ASD were enrolled in a 6 week, forced titration, open label examination of the selective serotonin reuptake inhibitor (SSRI) escitalopram. Doses increased at weekly intervals starting at 2.5mg daily with a maximum possible dose of 20 mg daily achieved by the end of the study. If adverse events were experienced, participants subsequently received the previously tolerated dose for the duration of study. SLC6A4 (5-HTTLPR) and HTR2A (rs7997012) genotype groups were assessed in relation to treatment outcomes and drug doses. RESULTS: Insistence on sameness and irritability symptoms significantly improved over the course of the 6 week treatment period (p<0.0001) in this open-label trial. There were no significant differences observed in the rate of symptom improvement over time across genotype groups. Similarly, dosing trajectory was not significantly associated with genotype groups. CONCLUSIONS: Previous studies have identified SLC6A4 and HTR2A associations with SSRI response in patients with depression and 5-HTTLPR (SLC6A4) associations with escitalopram response in ASD. We did not observe evidence for similar relationships in this ASD study.

Utility of the Gilliam Autism Rating Scale in research and clinical populations.

The Gilliam Autism Rating Scale (GARS) was developed as a relatively easy, inexpensive aid in the surveillance and diagnosis of autism. This study examined the validity of the GARS when used with a sample of 119 children with strict DSM-IV diagnoses of autism, ascertained from both clinical and research settings. The GARS consistently underestimated the likelihood that autistic children in this sample would be classified as having autism. The sample mean for the Autism Quotient, a hypothesized index of the likelihood of having autism, was 90.10, significantly below the reference mean of 100. Diagnostic classification according to criteria specified by the GARS resulted in a sensitivity of only .48. Limitations of rating scales in general and of the GARS specifically are discussed. It is recommended that clinicians and researchers using or considering using the GARS for autism diagnosis or ratings of autism severity recognize the need for further research regarding its use.

The pharmacological treatment of autistic spectrum disorders.

What role do medications play in the overall treatment of autistic spectrum disorders? In this review, the decision-making process involving identifying symptoms, initiating a pharmacological intervention, and monitoring that process is discussed. A review of the literature with an emphasis on controlled trials in autistic spectrum disorders is also undertaken.

Impact of recent findings on study design of future autism clinical trials.

There are specific challenges to studying the design of pharmacologic trials in child/adolescent and adult autism, such as subject stratification and parallel versus crossover designs. This article describes how optimal study design is influenced by subject selection and outcome measures chosen. Lessons learned in study design from the Research Units on Pediatric Psychopharmacology Autism Network trial with risperidone, Seaver Center trials with fluoxetine and valproate, Dartmouth trials with amantadine, and National Institutes of Health secretin trials are highlighted. The Internet System for Assessing Autistic Children system for managing multicenter clinical trials in autism and statistical issues in autism research are also described.

Case series: Adderall augmentation of serotonin reuptake inhibitors in childhood-onset obsessive compulsive disorder.

Current pharmacological treatment of obsessive compulsive disorder involves the use of selective serotonin reuptake inhibitors (SSRIs). However, a large proportion of patients does not respond fully to these medications despite receiving optimal doses and concomitant cognitive-behavioral therapy. Finding efficacious augmentation strategies has become an important goal of researchers and clinicians working with this population. In this case series, we describe four patients with childhood-onset obsessive compulsive disorder, and with partial or no response to SSRI treatment, who subsequently had a reduction of their symptoms with Adderall augmentation.

A pharmacogenetic study of escitalopram in autism spectrum disorders.

OBJECTIVE: To determine the effect of serotonin transporter polymorphism promoter region (5-HTTPLR) genotypic variation (low, intermediate, and high expression groups) on response to escitalopram treatment of children and adolescents with autism spectrum disorders (ASDs). METHOD: The study used a forced titration, open label design, with genotype blind until study completion. Participants were children and adolescents aged 4-17 years of age with a confirmed ASD (autistic disorder, Asperger's disorder, or pervasive developmental disorder, not otherwise specified). RESULTS: There was an interaction between genotype group and time on the Aberrant Behavior Checklist (ABC) Irritability Subscale (primary outcome variable) (linear maximum marginal likelihood estimation=-4.84, Z=-2.89, SE=1.67, P=0.004). Examination of baseline to last visit revealed that a genotype grouping based on a previous study of platelet 5-HT uptake revealed less response in the genotype group that had S/S genotype for 5-HTTLPR and did not have a diplotype in intron 1 previously shown to be associated with increased platelet 5-HT uptake. CONCLUSION: This genotype-blind, prospective pharmacogenetic study found the group of subjects with associated with the lowest platelet 5-HT uptake from previous study had the smallest reduction in ABC-Irritability scores after open label treatment with escitalopram. Replication is necessary to confirm these findings.