Mosaicism in tuberous sclerosis complex: Lowering the threshold for clinical reporting

Tuberous sclerosis complex (TSC) is a multi-system genetic disorder. Most patients have germline mutations in TSC1 or TSC2 but, 10%-15% patients do not have TSC1/TSC2 mutations detected on routine clinical genetic testing. We investigated the contribution of low-level mosaic TSC1/TSC2 mutations in unsolved sporadic patients and families with TSC. Thirty-one sporadic TSC patients negative on routine testing and eight families with suspected parental mosaicism were sequenced using deep panel sequencing followed by droplet digital polymerase chain reaction. Pathogenic variants were found in 22/31 (71%) unsolved sporadic patients, 16 were mosaic (median variant allele fraction [VAF] 6.8% in blood) and 6 had missed germline mutations. Parental mosaicism was detected in 5/8 families (median VAF 1% in blood). Clinical testing laboratories typically only report pathogenic variants with allele fractions above 10%. Our findings highlight the critical need to change laboratory practice by implementing higher sensitivity assays to improve diagnostic yield, inform patient management and guide reproductive counseling.

Comparing saliva and blood for the detection of mosaic genomic abnormalities that cause syndromic intellectual disability

We aimed to determine whether SNP-microarray genomic testing of saliva had a greater diagnostic yield than blood for pathogenic copy number variants (CNVs). We selected patients who underwent CMA testing of both blood and saliva from 23,289 blood and 21,857 saliva samples. Our cohort comprised 370 individuals who had testing of both, 224 with syndromic intellectual disability (ID) and 146 with isolated ID. Mosaic pathogenic CNVs or aneuploidy were detected in saliva but not in blood in 20/370 (4.4%). All 20 individuals had syndromic ID, accounting for 9.1% of the syndromic ID sub-cohort. Pathogenic CNVs were large in size (median of 46 Mb), and terminal in nature, with median mosaicism of 27.5% (not exceeding 40%). By contrast, non-mosaic pathogenic CNVs were 100% concordant between blood and saliva, considerably smaller in size (median of 0.65 Mb), and predominantly interstitial in location. Given that salivary microarray testing has increased diagnostic utility over blood in individuals with syndromic ID, we recommend it as a first-tier testing in this group.

Sporadic hypothalamic hamartoma is a ciliopathy with somatic and bi-allelic contributions

Hypothalamic hamartoma with gelastic seizures is a well-established cause of drug-resistant epilepsy in early life. The development of novel surgical techniques has permitted the genomic interrogation of hypothalamic hamartoma tissue. This has revealed causative mosaic variants within GLI3, OFD1 and other key regulators of the sonic-hedgehog pathway in a minority of cases. Sonic-hedgehog signalling proteins localize to the cellular organelle primary cilia. We therefore explored the hypothesis that cilia gene variants may underlie hitherto unsolved cases of sporadic hypothalamic hamartoma. We performed high-depth exome sequencing and chromosomal microarray on surgically resected hypothalamic hamartoma tissue and paired leukocyte-derived DNA from 27 patients. We searched for both germline and somatic variants under both dominant and bi-allelic genetic models. In hamartoma-derived DNA of seven patients we identified bi-allelic (one germline, one somatic) variants within one of four cilia genes-DYNC2I1, DYNC2H1, IFT140 or SMO. In eight patients, we identified single somatic variants in the previously established hypothalamic hamartoma disease genes GLI3 or OFD1. Overall, we established a plausible molecular cause for 15/27 (56%) patients. Here, we expand the genetic architecture beyond single variants within dominant disease genes that cause sporadic hypothalamic hamartoma to bi-allelic (one germline/one somatic) variants, implicate three novel cilia genes and reconceptualize the disorder as a ciliopathy.

Evidence for a Dual-Pathway, 2-Hit Genetic Model for Focal Cortical Dysplasia and Epilepsy

Background and Objectives

The 2-hit model of genetic disease is well established in cancer, yet has only recently been reported to cause brain malformations associated with epilepsy. Pathogenic germline and somatic variants in genes in the mechanistic target of rapamycin (mTOR) pathway have been implicated in several malformations of cortical development. We investigated the 2-hit model by performing genetic analysis and searching for germline and somatic variants in genes in the mTOR and related pathways.

Methods

We searched for germline and somatic pathogenic variants in 2 brothers with drug-resistant focal epilepsy and surgically resected focal cortical dysplasia (FCD) type IIA. Exome sequencing was performed on blood- and brain-derived DNA to identify pathogenic variants, which were validated by droplet digital PCR. In vitro functional assays of a somatic variant were performed.

Results

Exome analysis revealed a novel, maternally inherited, germline pathogenic truncation variant (c.48delG; p.Ser17Alafs*70) in NPRL3 in both brothers. NPRL3 is a known FCD gene that encodes a negative regulator of the mTOR pathway. Somatic variant calling in brain-derived DNA from both brothers revealed a low allele fraction somatic variant (c.338C>T; p.Ala113Val) in the WNT2 gene in 1 brother, confirmed by droplet digital PCR. In vitro functional studies suggested a loss of WNT2 function as a consequence of this variant. A second somatic variant has not yet been found in the other brother.

Discussion

We identify a pathogenic germline mTOR pathway variant (NPRL3) and a somatic variant (WNT2) in the intersecting WNT signaling pathway, potentially implicating the WNT2 gene in FCD and supporting a dual-pathway 2-hit model. If confirmed in other cases, this would extend the 2-hit model to pathogenic variants in different genes in critical, intersecting pathways in a malformation of cortical development. Detection of low allele fraction somatic second hits is challenging but promises to unravel the molecular architecture of FCDs.

Severe childhood speech disorder: Gene discovery highlights transcriptional dysregulation

OBJECTIVE

Determining the genetic basis of speech disorders provides insight into the neurobiology of human communication. Despite intensive investigation over the past 2 decades, the etiology of most speech disorders in children remains unexplained. To test the hypothesis that speech disorders have a genetic etiology, we performed genetic analysis of children with severe speech disorder, specifically childhood apraxia of speech (CAS).

METHODS

Precise phenotyping together with research genome or exome analysis were performed on children referred with a primary diagnosis of CAS. Gene coexpression and gene set enrichment analyses were conducted on high-confidence gene candidates.

RESULTS

Thirty-four probands ascertained for CAS were studied. In 11/34 (32%) probands, we identified highly plausible pathogenic single nucleotide (n = 10; CDK13, EBF3, GNAO1, GNB1, DDX3X, MEIS2, POGZ, SETBP1, UPF2, ZNF142) or copy number (n = 1; 5q14.3q21.1 locus) variants in novel genes or loci for CAS. Testing of parental DNA was available for 9 probands and confirmed that the variants had arisen de novo. Eight genes encode proteins critical for regulation of gene transcription, and analyses of transcriptomic data found CAS-implicated genes were highly coexpressed in the developing human brain.

CONCLUSION

We identify the likely genetic etiology in 11 patients with CAS and implicate 9 genes for the first time. We find that CAS is often a sporadic monogenic disorder, and highly genetically heterogeneous. Highly penetrant variants implicate shared pathways in broad transcriptional regulation, highlighting the key role of transcriptional regulation in normal speech development. CAS is a distinctive, socially debilitating clinical disorder, and understanding its molecular basis is the first step towards identifying precision medicine approaches.

Small interstitial 9p24.3 deletions principally involving KANK1 are likely benign copy number variants

A small heterozygous deletion involving KANK1 was originally reported in 2005 to cause cerebral palsy in one large Israeli family of Jewish Moroccan origin. There were nine affected children over two generations to five unaffected fathers. All of these children had congenital hypotonia that evolved into spastic quadriplegia over the first year of life, along with intellectual impairment and brain atrophy. The subsequent clinical depictions of other individuals with neurological disease harbouring a comparable KANK1 deletion have been extremely variable and most often quite dissimilar to the original family. The reported pathogenicity of these deletions has also been variable, due to an inconsistent nature of reported disease associations and limited data. We therefore sought to perform a review of the significance of small distal interstitial chromosome 9p24.3 deletions principally involving KANK1, including data from the VCGS cytogenetics laboratory. We found that carrier parents do not appear to display an increased frequency of neurological disease, individuals with a small KANK1 deletion have sometimes been found to have an alternate genetic diagnosis that explained their neurological condition, and small KANK1 deletions can be seen with approximate equal frequency in case and control populations. These data led us to conclude that small deletions involving KANK1 do not cause a highly-penetrant influence of large effect size and they are unlikely to contribute significantly to the aetiology of disease in patients with development delay, intellectual disability, autism or cerebral palsy. We recommend searching for an alternate explanation for disease in individuals with a neurological disorder found to have a small deletion involving KANK1.

Characterization of speech and language phenotype in children with NRXN1 deletions

Neurexin 1 gene (NRXN1) deletions are associated with several neurodevelopmental disorders. Communication difficulties have been reported, yet no study has examined specific speech and language features of individuals with NRXN1 deletions. Here, we characterized speech and language phenotypes in 21 children (14 families), aged 1.8-17 years, with NRXN1 deletions. Deletions ranged from 74 to 702 kb and consisted mostly of either exons 1-3 or 1-5. Speech sound disorders were frequent (69%), although few were severe. The majority (57%) of children had difficulty with receptive and/or expressive language, although no homogeneous profiles of deficit were seen across semantic, morphological, or grammatical systems. Social language difficulties were seen in over half the sample (53%). All but two individuals with language difficulties also had intellectual disability/developmental delay. Overall, while speech and language difficulties were common, there was substantial heterogeneity in the severity and type of difficulties observed and no striking communication phenotype was seen. Rather, the speech and language deficits are likely part of broader concomitant neurodevelopmental profiles (e.g., intellectual disability, social skill deficits). Nevertheless, given the high rate of affectedness, it is important speech/language development is assessed so interventions can be applied during childhood in a targeted and timely manner.

Deep phenotyping of speech and language skills in individuals with 16p11.2 deletion

Recurrent deletions of a ~600-kb region of 16p11.2 have been associated with a highly penetrant form of childhood apraxia of speech (CAS). Yet prior findings have been based on a small, potentially biased sample using retrospectively collected data. We examine the prevalence of CAS in a larger cohort of individuals with 16p11.2 deletion using a prospectively designed assessment battery. The broader speech and language phenotype associated with carrying this deletion was also examined. 55 participants with 16p11.2 deletion (47 children, 8 adults) underwent deep phenotyping to test for the presence of CAS and other speech and language diagnoses. Standardized tests of oral motor functioning, speech production, language, and non-verbal IQ were conducted. The majority of children (77%) and half of adults (50%) met criteria for CAS. Other speech outcomes were observed including articulation or phonological errors (i.e., phonetic and cognitive-linguistic errors, respectively), dysarthria (i.e., neuromuscular speech disorder), minimal verbal output, and even typical speech in some. Receptive and expressive language impairment was present in 73% and 70% of children, respectively. Co-occurring neurodevelopmental conditions (e.g., autism) and non-verbal IQ did not correlate with the presence of CAS. Findings indicate that CAS is highly prevalent in children with 16p11.2 deletion with symptoms persisting into adulthood for many. Yet CAS occurs in the context of a broader speech and language profile and other neurobehavioral deficits. Further research will elucidate specific genetic and neural pathways leading to speech and language deficits in individuals with 16p11.2 deletions, resulting in more targeted speech therapies addressing etiological pathways.

ADGRV1 is implicated in myoclonic epilepsy

OBJECTIVE

To investigate the significance of variation in ADGRV1 (also known as GPR98, MASS1, and VLGR1), MEF2C, and other genes at the 5q14.3 chromosomal locus in myoclonic epilepsy.

METHODS

We studied the epilepsy phenotypes of 4 individuals with 5q14.3 deletion and found that all had myoclonic seizures. We then screened 6 contiguous genes at 5q14.3, MEF2C, CETN3, MBLAC2, POLR3G, LYSMD3, and ADGRV1, in a 95-patient cohort with epilepsy and myoclonic seizures. Of these genes, point mutations in MEF2C cause a phenotype involving seizures and intellectual disability. A role for ADGRV1 in epilepsy has been proposed previously, based on a recessive mutation in the Frings mouse model of audiogenic seizures, as well as a shared homologous region with another epilepsy gene, LGI1.

RESULTS

Six patients from the myoclonic epilepsy cohort had likely pathogenic ultra-rare ADGRV1 variants, and statistical analysis showed that ultra-rare variants were significantly overrepresented when compared to healthy population data from the Genome Aggregation Database. Of the remaining genes, no definite pathogenic variants were identified.

SIGNIFICANCE

Our data suggest that the ADGRV1 variation contributes to epilepsy with myoclonic seizures, although the inheritance pattern may be complex in many cases. In patients with 5q14.3 deletion and epilepsy, ADGRV1 haploinsufficiency likely contributes to seizure development. The latter is a shift from current thinking, as MEF2C haploinsufficiency has been considered the main cause of epilepsy in 5q14.3 deletion syndrome. In cases of 5q14.3 deletion and epilepsy, seizures likely occur due to haploinsufficiency of one or both of ADGRV1 and MEF2C.

Loss of RMI2 Increases Genome Instability and Causes a Bloom-Like Syndrome

Bloom syndrome is a recessive human genetic disorder with features of genome instability, growth deficiency and predisposition to cancer. The only known causative gene is the BLM helicase that is a member of a protein complex along with topoisomerase III alpha, RMI1 and 2, which maintains replication fork stability and dissolves double Holliday junctions to prevent genome instability. Here we report the identification of a second gene, RMI2, that is deleted in affected siblings with Bloom-like features. Cells from homozygous individuals exhibit elevated rates of sister chromatid exchange, anaphase DNA bridges and micronuclei. Similar genome and chromosome instability phenotypes are observed in independently derived RMI2 knockout cells. In both patient and knockout cell lines reduced localisation of BLM to ultra fine DNA bridges and FANCD2 at foci linking bridges are observed. Overall, loss of RMI2 produces a partially active BLM complex with mild features of Bloom syndrome.

Cells contain specific protein complexes that are needed to correct errors during the replication and segregation of DNA. Impairment in the activity of these proteins can be detrimental to the viability of the cell and organism development. Bloom syndrome is an example of a genome instability disorder where cells cannot efficiently untangle DNA after replication. The only gene that is known to cause Bloom syndrome is the BLM helicase. In this article, we describe two affected individuals with Bloom-like features with a homozygous deletion of the RMI2 gene. The RMI2 protein has previously been shown to form a complex with BLM, topoisomerase III alpha and RMI1. Deletion of RMI2 in patient and unrelated cell lines show hyper-recombination and chromosome entanglements during cell division. Furthermore, we show that the BLM and FANCD2 proteins are diminished in the binding of DNA bridges that need to be dissolved during the late stages of cell division. Therefore, loss of RMI2 produces a milder Bloom phenotype and impairs the full activity of the BLM complex.

Polydrug use at raves by a Western Australian sample

This study aimed to quantify the patterns of drug use among a group of participants in the rave scene in Perth, Western Australia. Interviews were conducted with 83 people who had recently been to a 'rave'. The study incorporated a semi-structured qualitative interview and a structured quantitative questionnaire. This paper reports on the quantitative data collected concerning patterns of drug use in association with the last rave attended. Use of 'dance drugs' (ecstasy, amphetamines or LSD) was reported by 86.8% of the 76 respondents who had used at least one drug in association with their last rave. Nearly 80% of these had also used at least one other drug on this occasion (mean number used = 2.4). Cannabis and inhalants were the drugs most commonly combined with the 'dance drugs', several respondents used more than one 'dance drug' concurrently and 16.7% had used alcohol. It seems that a significant proportion of those using 'dance drugs' in association with raves and dance parties are mixing these drugs with other substances despite harm reduction advice to the contrary. The need for more research in this area is discussed.

Periventricular heterotopia, mental retardation, and epilepsy associated with 5q14.3-q15 deletion

BACKGROUND

Periventricular heterotopia (PH) is an etiologically heterogeneous disorder characterized by nodules of neurons ectopically placed along the lateral ventricles. Most affected patients have seizures and their cognitive level varies from normal to severely impaired. At present, two genes have been identified to cause PH when mutated. Mutations in FLNA (Xq28) and ARFGEF2 (20q13) are responsible for X-linked bilateral PH and a rare autosomal recessive form of PH with microcephaly. Chromosomal rearrangements involving the 1p36, 5p15, and 7q11 regions have also been reported in association with PH but the genes implicated remain unknown. Fourteen additional distinct anatomoclinical PH syndromes have been described, but no genetic insights into their causes have been gleaned.

METHODS

We report the clinical and imaging features of three unrelated patients with epilepsy, mental retardation, and bilateral PH in the walls of the temporal horns of the lateral ventricles, associated with a de novo deletion of the 5q14.3-15 region. We used microarray-based comparative genomic hybridization to define the boundaries of the deletions.

RESULTS

The three patients shared a common deleted region spanning 5.8 Mb and containing 14 candidate genes.

CONCLUSION

We identified a new syndrome featuring bilateral periventricular heterotopia (PH), mental retardation, and epilepsy, mapping to chromosome 5q14.3-q15. This observation reinforces the extreme clinical and genetic heterogeneity of PH. Array comparative genomic hybridization is a powerful diagnostic tool for characterizing causative chromosomal rearrangements of limited size, identifying potential candidate genes for, and improving genetic counseling in, malformations of cortical development.

BAC-based PCR fragment microarray: high-resolution detection of chromosomal deletion and duplication breakpoints

The introduction of molecular techniques in conjunction with classical cytogenetic methods has in recent years greatly improved the diagnostic potential for chromosomal abnormalities. In particular, microarray-comparative genomic hybridization (CGH) based on the use of BAC clones promises a sensitive strategy for the detection of DNA copy-number changes on a genomewide scale, offering a resolution as high as >30,000 "bands" (as defined by the number of BACs within the currently highest-density BAC array) [Ishkanian et al., 2004]. We have tested the possibility of further increasing this resolution using PCR fragments generated from individual BAC clones. Using this approach, we have efficiently defined the proximal and distal breakpoints in two cytogenetic cases, one duplication and one deletion, to within 5-20 kb. The results support the potential use of BAC-based PCR fragments to further improve the resolution of the microarray-CGH strategy by an order of magnitude.

Psychiatric morbidity and substance use in young people aged 13-15 years: results from the Child and Adolescent Survey of Mental Health

BACKGROUND

Psychoactive substance use is strongly associated with psychiatric morbidity in both adults and adolescents.

AIMS

To determine which of alcohol, nicotine and cannabisis mostclosely linked to psychiatric disorders in early adolescence.

METHOD

Data from 2624 adolescents aged 13-15 years were drawn from a national mental health survey of children. The relationship between psychiatric morbidity and smoking, drinking and cannabis use was examined by logistic regression analyses.

RESULTS

Having a psychiatric disorder was associated with an increased risk of substance use. Greater involvement with any one substance increased the risk of other substance use. Analyses of the interactions between smoking, drinking and cannabis use indicated that the relationship between substance use and psychiatric morbidity was primarily explained by regular smoking and (to a lesser extent) regular cannabis use.

CONCLUSIONS

In this sample, links between substance use and psychiatric disorders were primarily accounted for by smoking. The strong relationship is likely to be due to a combination of underlying individual constitutional factors and drug-specific effects resulting from consumption over the period of adolescent development and growth.

Drug use and initiation in prison: results from a national prison survey in England and Wales

AIMS

To investigate heroin and cocaine use in a sample of British prisoners, and to explore the characteristics of inmates who use these drugs for the first time while in prison.

DESIGN, PARTICIPANTS

A cross-sectional survey of all prisons in England and Wales conducted as part of a major national study of psychiatric morbidity. A total of 3142 prisoners (88.2% of those selected) completed a structured interviewer-administered questionnaire.

MEASUREMENTS

Interview measures of personal demographics, social history, psychiatric morbidity and drug use. Personality disorders were diagnosed via the Structured Clinical Interview for DSM-IV (SCID-II) and neurotic symptoms were assessed using the revised Clinical Interview Schedule (CIS-R).

FINDINGS

More than 60% of the heroin users and cannabis users reported that they had used these drugs in prison compared with less than a quarter of the life-time cocaine users. More than a quarter of the heroin users reported that they had initiated use of this drug in prison. The extent of an individual's experience of prison was related more consistently to heroin and/or cocaine use in and out of prison than other personal background, social history or psychiatric variables assessed.

CONCLUSIONS

The findings indicate that prisons are a high-risk environment for heroin and other drug initiation and use. Although related to drug use, psychiatric variables were not generally associated with initiation in prison, which was dominated by prison exposure. There is a need to explore ways of reducing heroin initiation in prison as part of a broader risk-prevention strategy.

Psychosis and drug dependence: results from a national survey of prisoners

BACKGROUND

The links between drug use and psychosis are of major aetiological and prognostic significance. Psychosis and drug dependence frequently co-occur within the prison population, providing the opportunity to study this link more closely.

AIMS

To explore the relationship between psychosis and drug dependence in a sample of prisoners.

METHOD

A total of 3142 prisoners were surveyed nationally, and structured clinical data were obtained from a subsample of 503 respondents. Psychiatric assessment was based on the Schedules for Clinical Assessment in Neuropsychiatry (version 1.0). Measures of amphetamine, cannabis, cocaine and heroin use and dependence were obtained through self-report.

RESULTS

Logistic regression analyses indicated that first use of amphetamines or cocaine before the age of 16 years and severe cannabis or cocaine dependence were related to an increased risk of psychosis. In contrast, severe dependence on heroin was associated with a reduced risk of this classification.

CONCLUSIONS

Severe dependence on cannabis and psychostimulants is associated with a higher risk of psychosis and is in contrast to severe dependence on heroin, which has a negative relationship with psychosis.

Understanding reasons for drug use amongst young people: a functional perspective

This study uses a functional perspective to examine the reasons young people cite for using psychoactive substances. The study sample comprised 364 young poly-drug users recruited using snowball-sampling methods. Data on life-time and recent frequency and intensity of use for alcohol, cannabis, amphetamines, ecstasy, LSD and cocaine are presented. A majority of the participants had used at least one of these six drugs to fulfil 11 of 18 measured substance use functions. The most popular functions for use were using to: relax (96.7%), become intoxicated (96.4%), keep awake at night while socializing (95.9%), enhance an activity (88.5%) and alleviate depressed mood (86.8%). Substance use functions were found to differ by age and gender. Recognition of the functions fulfilled by substance use should help health educators and prevention strategists to make health messages about drugs more relevant and appropriate to general and specific audiences. Targeting substances that are perceived to fulfil similar functions and addressing issues concerning the substitution of one substance for another may also strengthen education and prevention efforts.

Substance use among young people: the relationship between perceived functions and intentions

AIMS

To explore the relationship between young people's use of psychoactive substances, perceived functions for using, the experience of negative effects, and the influences of these variables on their intention to use substances again.

DESIGN

Cross-sectional survey in which respondents were purposively recruited using snowballing techniques.

SETTING

Interviews were conducted in informal community settings.

PARTICIPANTS

One hundred young drug and alcohol users (45 females) aged between 16 and 21 years.

MEASUREMENTS

Life-time prevalence, current frequency and intensity of substance use and intentions to use again were assessed for four target substances (alcohol, cannabis, amphetamines and ecstasy) together with measures of the perceived functions for their use and peer substance involvement.

FINDINGS

The life-time experience of negative effects from using the assessed substances was not found to correlate with current consumption patterns. Statistically significant associations were observed between the reported frequency of taking substances and the perceived social/contextual and/or mood altering functions cited for their consumption. The substance use function measures together with the reported extent of peer use were significant predictors of intentions to use again.

CONCLUSIONS

If these findings are confirmed in larger studies, educational and preventative efforts may need to acknowledge the positive personal and social functions which different substances serve for young people. The results also call into question the extent to which the experience of negative effects influences future patterns of use.

Raves, drugs and experience: drug use by a sample of people who attend raves in Western Australia

AIMS

To investigate the patterns of drug use among a sample of people in the rave scene in Perth, Western Australia and test the hypothesis that those who were less experienced in their drug use had less drug-related knowledge.

DESIGN

Respondents were recruited through flyers in cafes, clothing and music stores and through snowballing. They were paid $20 for a 1 1/2 hour interview which comprised both qualitative and quantitative components.

SETTING

Respondents were interviewed in cafes or restaurants, private dwellings, agencies or other public spaces.

PARTICIPANTS

Eighty-three people who had been to a rave in the prior 6 months. Their mean age was 18.9 years (range 13-48) and 53% were male.

MEASUREMENTS

Brief history of drug use, HIV risk behaviour, knowledge of drug-related harm and side effects experienced from drugs.

FINDINGS

The group was unremarkable apart from their drug use. Ninety per cent of respondents had ever used LSD, 76% had used ecstasy and 69% had used amphetamines. Before, during or after the last rave attended 52% used cannabis and 35% had used each of amphetamines and LSD. Those who were less experienced in their drug use had less knowledge about drugs. Many respondents began using 'dance drugs' while they were still at school.

CONCLUSIONS

Those with less drug-using experience may have less drug-related knowledge and may be at greater risk of harm. Strategies should be implemented which involve people in the scene, promoters, health workers and the authorities to reduce drug-related harm associated with raves and other dance events.