A review of cannabis allergy in the early days of legalization

Cannabis allergy is a burgeoning field; consequently, research is still in its infancy and allergists' knowledge surrounding this topic is limited. As cannabis legalization expands across the world, it is anticipated that there will be an increase in cannabis use. Thus, we hypothesize that a concomitant rise in the incidence of allergy to this plant can be expected. Initiatives aimed at properly educating health care professionals are therefore necessary. This review presents the most up-to-date information on a broad range of topics related to cannabis allergy. Although the clinical features of cannabis allergy are becoming more well described and recognized, the tools available to make a correct diagnosis are meager and often poorly accessible. In addition, research on cannabis allergy is still taking its first steps, and new and potentially groundbreaking findings in this field are expected to occur in the next few years. Finally, although therapeutic approaches are being developed, patient and physician education regarding cannabis allergy is certainly needed.

Practices and attitudes of providers towards continuity of care with patients using prescription contraceptives

The aim of this study was to explore provider practices and attitudes towards routine follow-up counselling after prescription of contraceptives. An anonymous 16-item survey was pilot-tested and sent to providers of the Internal Medicine, Family Medicine, Pediatrics, and OBGYN departments of Thomas Jefferson University Hospitals (TJUH), an urban academic medical centre in Philadelphia, PA, USA. Frequency and descriptive statistics were used to analyse quantitative data while a framework analysis approach was applied to open-ended questions. Fifty percent of providers said they typically follow up with patients regarding a newly prescribed contraceptive. Only 15.3% said they do for an existing prescription. Eighty-three percent reported that it is important though only 30% believed follow-up guidelines were clear. Ultimately, there is a gap between providers' interest in delivering follow-up care and established direction on how to do so.Impact StatementWhat is already known on the subject? Prescription contraceptive adherence is suboptimal. However, it is known that proactive follow-up has positive effects on prescription contraceptive adherence.What do the results of the study add? Most respondents believe that patients take their prescription contraception as prescribed. In light of this finding, providers are less likely to follow up with an existing prescription contraceptive. Interestingly, most respondents do believe that follow-up is important for patients using prescribed contraception but endorse that guidelines about follow-up are neither established nor clear.What are the implications of these findings for clinical practice and/or further research? Patient adherence to prescription contraceptives can be improved through optimised routine patient follow-up after initial prescription. This must be done in ways that minimise burdens to both patients and providers. Providers could benefit from clear guidelines regarding best practices. Future research is needed to understand how providers can best support patients on their contraceptive journey.

Impact of cannabis knowledge and attitudes on real-world practice

BACKGROUND

Increased cannabis consumption worldwide challenges allergists because of an upsurge in cannabis allergy and need to discuss cannabis with patients.

OBJECTIVE

To determine the knowledge, attitudes, and practices regarding cannabis among allergists and their approach to recognizing and diagnosing suspected cannabis allergy.

METHODS

The International Allergist Canna Knowledge, Attitudes, and Practices Survey was completed by members from 3 International Allergy Societies. Survey questions included the following: 13 on cannabis attitudes, 7 on cannabis knowledge, and 4 on real-world allergy practices. Knowledge level was dichotomized and Statistical Package for the Social Sciences TwoStep Cluster Analysis grouped participants by attitudes. Multivariate analysis determined the relationship of knowledge and attitude to practice delivery.

RESULTS

Of 570 eligible surveys started, 445 (78.1%) were completed. Participants were 49.7% of female sex, 65.9% aged 24 to 56 years, approximately 70% in practice for more than or equal to 10 years, and 29.2% practicing in an area where cannabis use is illegal. Of the respondents, 43.1% reported consulting on patients with suspected cannabis allergy and 54.7% had undertaken skin prick testing, in vitro cannabis testing, or both. Statistically significant differences were found between the 3 societies for most variables analyzed. Analysis of attitudes revealed 3 clusters named Traditional, Progressive, and Unsure. Those with more progressive attitudes toward cannabis and who had more knowledge were more comfortable speaking to patients about cannabis and more often asked patients on how often and how they used cannabis (all P < .001).

CONCLUSION

Varying knowledge and attitudes toward cannabis affecting comfort communicating with patients about cannabis were found in members of 3 allergy societies supporting the need for more cannabis research and education.

Cannabis-related allergies: An international overview and consensus recommendations

Cannabis is the most widely used recreational drug in the world. Cannabis sativa and Cannabis indica have been selectively bred to develop their psychoactive properties. The increasing use in many countries has been accelerated by the COVID-19 pandemic. Cannabis can provoke both type 1 and type 4 allergic reactions. Officially recognized allergens include a pathogenesis-related class 10 allergen, profilin, and a nonspecific lipid transfer protein. Other allergens may also be relevant, and recognition of allergens may vary between countries and continents. Cannabis also has the potential to provoke allergic cross-reactions to plant foods. Since cannabis is an illegal substance in many countries, research has been hampered, leading to challenges in diagnosis since no commercial extracts are available for testing. Even in countries such as Canada, where cannabis is legalized, diagnosis may rely solely on the purchase of cannabis for prick-to-prick skin tests. Management consists of avoidance, with legal issues hindering the development of other treatments such as immunotherapy. Education of healthcare professionals is similarly lacking. This review aimed to summarize the current status of cannabis allergy and proposes recommendations for the future management of this global issue.

Occupational Allergies to Cannabis

Within the last decade there has been a significant expansion in access to cannabis for medicinal and adult nonmedical use in the United States and abroad. This has resulted in a rapidly growing and diverse workforce that is involved with the growth, cultivation, handling, and dispensing of the cannabis plant and its products. The objective of this review was to educate physicians on the complexities associated with the health effects of cannabis exposure, the nature of these exposures, and the future practical challenges of managing these in the context of allergic disease. We will detail the biological hazards related to typical modern cannabis industry operations that may potentially drive allergic sensitization in workers. We will highlight the limitations that have hindered the development of objective diagnostic measures that are essential in separating "true" cannabis allergies from nonspecific reactions/irritations that "mimic" allergy-like symptoms. Finally, we will discuss recent advances in the basic and translational scientific research that will aid the development of diagnostic tools and therapeutic standards to serve optimal management of cannabis allergies across the occupational spectrum.

The impact of mental toughness and postural abnormalities on dysfunctional breathing in athletes

Background: While asthma and exercise-induced bronchoconstriction (EIB) can explain some cases of exertional dyspnea, the differential diagnosis of dyspnea is extensive. Dysfunctional breathing (DB) is a condition that is often overlooked and underdiagnosed. Pharmacologic treatments are available and widely utilized by clinicians for exertional dyspnea, but a better understanding of the non-pharmacologic treatments as well as psychological factors that play a role in DB can provide professional, elite amateurs, and recreational athletes with more therapeutic options.Measurement tools for mental toughness: Given the psychological components involved with these conditions, a tool to measure domains of sports mental toughness in athletes could help medical providers create a more comprehensive athlete profile which can be used in conjunction with standard pharmacologic therapy to provide a more effective treatment plan.Diagnosing DB: While normal breathing mechanics help shape appropriate posture and spinal stabilization, DB has been shown to contribute to pain and motor control deficits resulting in dysfunctional movement patterns, which further contribute to DB. Most respiratory specialists are unaware of how to assess the role of faulty sports technique, especially running gait, in dysfunctional breathing patterns making it difficult to recommend appropriate treatment and offer referrals for relevant therapies.Assessing postural changes: Three key components of proper running gait are reviewed and described in detail including trunk counter-rotation, extension of atlanto-occipital joint in conjunction with a forward tilted trunk, and ankle and hip joint range of motion.Conclusions: When underlying gait abnormalities and mental skills are addressed properly, they can disrupt poor breathing mechanics, facilitating a transition away from DB and toward healthier breathing patterns.KEY POINTS In summary, the following points should be considered when evaluating athletes who are having difficulty breathing even when compliant with their medications or if there is not an indication of asthma or EIB:Assess dysfunctional breathing (DB) with Nijmegen questionnaire (NQ).If DB is present, measure mental skills using the Sisu Quiz to determine an athlete's mental skills profile.Evaluate postural changes that may impact an athlete's ability to breathe.Using the three tools of the NQ, Sisu Quiz, and Postural assessments creates an athlete profile that is clinically useful to improve breathing technique.DB is often mistaken for other conditions for which medications are prescribed. By identifying DB early and making appropriate changes may negate or reduce the need for pharmacotherapy.Improving DB will improve athletic performance.

Cannabis attitudes and patterns of use among followers of the Allergy & Asthma Network

BACKGROUND

Cannabis use in patients with allergy/asthma, a high-risk group for adverse effects to cannabis, is unknown.

OBJECTIVE

To determine the patterns of use and attitudes toward cannabis in patients with allergy/asthma.

METHODS

An anonymous online survey on cannabis attitudes and use was conducted through the Adult Allergy & Asthma Network. The Asthma Control Test assessed asthma burden. Cluster analyses determined group phenotypes and factor analyses condensed cannabis subjective effects into similar response patterns.

RESULTS

A total of 88 of 489 respondents (18.0%) currently use cannabis with most at the age of less than 50 years old, of female sex, and of White race. Of the noncannabis users (N = 401), 2.5% reported cannabis allergy. Cluster analysis revealed that a liberal attitude toward cannabis was associated with current cannabis use (P < .001). Among current cannabis users, 40.9% of their physicians inquired on cannabis use; only 37.5% of users wanted to discuss cannabis. In addition, 65.9% used cannabis for medical or medical/recreational purposes. Cannabinoids used were tetrahydrocannabinol (33.0%), cannabidiol (19.3%), or both (47.7%). Smoked and vaped cannabis were reported by 53.4% and 35.2%, respectively. Furthermore, 51 cannabis users (58.0%) reported current asthma with 39.2% uncontrolled; of these, 50% smoked cannabis. Compared with current participants with asthma not using cannabis, those currently using cannabis experienced similar levels of asthma control, quality of life, and frequency of asthma exacerbations. Positive effects were endorsed more than negative effects to cannabis (P < .001). Moreover, 19.3% of cannabis users reported coughing that was associated with smoking cannabis (P < .001).

CONCLUSION

Cannabis was used by less than 20% of the respondents with positive effects more frequent than negative effects. Half of cannabis users with uncontrolled asthma smoke cannabis, but only a minority of the physicians inquire about its use.

Cannabis: An Emerging Occupational Allergen?

Cannabis is the most commonly used psychoactive drug. In recent years, Cannabis access has expanded for both medicinal and non-medicinal has grown. This is also marked with an increasing number of individuals gaining employment in this emerging industry. In this article, we briefly discuss the health hazards associated with Cannabis exposure with an emphasis on the potential for allergic reactions in workers who handle and process Cannabis plant.

Attitudes about cannabis mediate the relationship between cannabis knowledge and use in active adult athletes

BACKGROUND

Little is known about how cannabis knowledge and attitudes impact cannabis use behavior.

OBJECTIVE

To test the knowledge-attitudes-behavior paradigm in active adult athletes.

DESIGN

The Athlete Pain, Exercise, and Cannabis Experience (PEACE) Survey, a cross-sectional survey study, used social media and email blasts to recruit participants and SurveyGizmo to collect data.

PARTICIPANTS

Self-defined active adult athletes (n = 1161).

MAIN MEASURES

Knowledge about cannabis was evaluated with four questions. Attitudes toward cannabis was evaluated with 11 questions. The attitudes questions were used in a TwoStep Cluster analysis in SPSS to assign group membership by attitudes. Chi-square was used to determine if there were differences in cluster membership by demographic factors and if knowledge about cannabis differed by cluster membership. Regression analysis was performed to determine if cannabis attitudes mediated the relationship between cannabis knowledge and cannabis use.

KEY RESULTS

A three-cluster solution was the best fit to the data. The clusters were named Conservative (n = 374, 32.2%), Unsure (n = 533, 45.9%), and Liberal (n = 254, 21.9). There was a significant difference among the clusters for all 11 attitudes items (all p < 0.001). Attitude cluster membership was significantly different by age (p < 0.001), primary sport (p < 0.05), and knowledge about cannabis (p < 0.001). Athletes in the liberal cluster answered the knowledge questions correctly most often. Attitudes mediated the relationship between cannabis knowledge and cannabis use [Never (32.4%), Past (41.6%), Current (26.0%)] with athletes in the liberal cluster showing more knowledge and greater likelihood to be a current cannabis user (p < 0.001). Among current cannabis users there were differential patterns of cannabis use depending on their attitudes and knowledge; liberal athletes tended to co-use THC and CBD and used cannabis longer. (p < 0.001).

CONCLUSIONS

Cannabis education needs to consider attitudes about cannabis, especially among those who might benefit from medical cannabis.

Special Considerations and Perspectives for Exercise-Induced Bronchoconstriction (EIB) in Olympic and Other Elite Athletes

Diagnosing and treating elite and Olympic athletes with exercise-induced bronchoconstriction has been well established. However, a subset of elite and Olympic athletes with exercise-induced bronchoconstriction experience symptoms of breathlessness due to lack of adherence, improper medications, and/or generalized breathing dysfunction. A short review of traditional treatment plans for elite and Olympic athletes is presented along with the challenges of adherence, managing dysfunctional breathing, and measuring and treating mental skills deficits that may impact breathing. Elite and Olympic athletes may not respond to traditional treatment for exercise-induced bronchospasm, and we present some of the reasons why the athletes fail to respond. Furthermore, we present information on how to detect and treat elite and Olympic athletes with difficult-to-treat asthma. As part of this review we developed a flow diagram for medical providers to identify the reasons for lack of response to traditional treatment plans for exercise-induced bronchoconstriction with options for other treatment modalities.

Age related differences in cannabis use and subjective effects in a large population-based survey of adult athletes

BACKGROUND

There is a paucity of information regarding cannabis use behaviors in adult community-based athletes as most research in athletes has focused on misuse of cannabis in elite, adolescent, university-based athletes. We aimed to determine whether age related differences exist in patterns of cannabis use and subjective effects to cannabis in adult athletes.

METHODS

The Athlete PEACE Survey used mainly social media and email blasts to recruit and SurveyGizmo to collect data. Cannabis patterns of use (duration of use, frequency of use, routes of administration, cannabinoid used, concurrent use with exercise), benefits, and adverse effects were reported. Age was reported by decade from 21 to ≥60. Age trends in cannabis use patterns and subjective effects were assessed using linear trend analysis.

RESULTS

Of the 1161 participants, 301 (26%) athletes currently used cannabis. Younger athletes compared to older athletes reported significantly more positive and adverse subjective effects to cannabis, used cannabis longer, and used both tetrahydrocannabinol and cannabidiol for medical and recreational purposes. Younger athletes used cannabis concurrently with exercise more often than older athletes and consumed edibles, vaporized, and smoked more than older athletes.

CONCLUSIONS

We found age-related cannabis patterns of use and subjective effects to cannabis. Concerns about cannabis mis-use and abuse in athletes maybe overstated with the potential benefits (improved sleep, decreased anxiety, less pain) outweighing the adverse effects (increased anxiety, increased appetite, difficulty concentrating).

Cannabis use in active athletes: Behaviors related to subjective effects

Cannabis use has not been well characterized in athletes. Studies primarily examine problematic use or its categorization by anti-doping bodies as a banned substance. Patterns of use, reasons for use, and responses to cannabis consumption have not been studied in a community-based sample of adult athletes. The Athlete PEACE Survey examined cannabis use patterns and subjective effects to cannabis in a community-based cohort of adult athletes. We used mainly social media and email blasts to recruit and SurveyGizmo to collect data. 1,161 (91.1%) of the 1,274 athletes taking the survey completed it. Current cannabis use was evaluated by asking "In the past two weeks, have you used marijuana (including THC and/or CBD)?" and cannabis type used was assessed by asking "What do you primarily use THC, CBD, or both?". Cannabis benefits and adverse effects (i.e. subjective effects) and patterns of use were reported. 302 athletes (26%) currently use cannabis of whom 301 had complete data for cluster analysis. Cluster analysis was used to determine cannabis user phenotypes and exploratory factor analysis (EFA) was used to create subjective effects factors. Associations between cannabis user phenotype clusters and the subjective effects factors were explored using multivariate analysis. Cluster analysis identified three statistically distinct cannabis user phenotypes: (1) older athletes who primarily use medical CBD, (2) mixed age athletes who use cannabis mainly recreationally with both THC and CBD use, and (3) mixed age athletes who used cannabis the longest with primary THC and CBD use. EFA showed three subjective effects factors: (1) Well-being, (2) Calm, and (3) Adverse. Mean positive subjective were higher than mean adverse subjective effects (p<0.001). The cluster using THC and CBD showed the highest mean scores for all three subjective effects factors (p<0.001). Athletes who use a combination of THC and CBD exhibited the most benefit to well-being and calm with minimal adverse effects. Our methodology can be used to develop real-world evidence to inform future use of medical cannabis products.

Oral Clefts, Maternal Smoking, and TGFA: A Meta-Analysis of Gene-Environment Interaction

Objective

A meta-analysis was performed to examine the association among maternal cigarette smoking, infant genotype at the Taq1 site in the transforming growth factor α (TGFA) locus, and risk of nonsyndromic oral clefts, both cleft palate (CP) and cleft lip with or without cleft palate (CL/P).

Design

Five published case-control studies were included in the meta-analyis. Pooled Mantel-Haenszel odds ratios (OR) and 95% confidence intervals (CIs) were computed. Gene-environment interaction was also assessed by using the pooled data in a case-only analysis and polytomous logistic regression.

Results

Among nonsmoking mothers, there was no evidence of any increased risk for CP if the infant carried the TGFA Taq1 C2 allele. If the mother reported smoking, however, there was an overall increased risk for CP if the infant carried the C2 allele (ORsmokers = 1.95; 95% CI = 1.22 to 3.10). TGFA genotype did not increase risk to CL/P, regardless of maternal smoking status. Polytomous logistic regression revealed a significant overall smoking effect for CL/P (OR = 1.64, 95% CI = 1.33 to 2.02) and CP (OR = 1.42, 95% CI = 1.06 to 1.90).

Conclusions

While maternal smoking was a consistent risk factor for both CL/P and CP across all studies, the suggestive evidence for gene-environment interaction between the infant's genotype at the Taq1 marker in TGFA and maternal smoking was limited to CP. Furthermore, evidence for such gene-environment interaction was strongest in a case-control study drawn from a birth defect registry where infants with non-cleft defects served as controls.

Prevalence and correlates of alcohol and cannabis use disorders in the United States: results from the national longitudinal study of adolescent health

BACKGROUND

Limited current information on the epidemiology of lifetime alcohol and cannabis use disorders in the United States is available.

AIMS

To present detailed information about the prevalence and sociodemographic correlates of lifetime alcohol and cannabis use disorders rates in the United States. To examine gender differences in hazard ratios for the onset of alcohol and cannabis dependence.

METHODS

Participants in Wave IV of the National Longitudinal Study of Adolescent Health (N=15,500, age range: 24-32) were interviewed between 2008 and 2009. Participants who exceeded screening thresholds were queried about lifetime DSM-IV alcohol and marijuana abuse and dependence symptoms. Age of substance dependence onset was queried.

RESULTS

Lifetime rates of alcohol abuse and dependence were 11.8 and 13.2%. Lifetime rates of cannabis abuse and dependence were 3.9 and 8.3%. Lifetime alcohol and cannabis dependence onset peaks were 23 and 20. Correlates of lifetime alcohol abuse included being male (OR 1.4), African-American (OR 0.7), income in the 2nd or 3rd quartile (OR 0.7 and 0.6). Correlates of lifetime alcohol dependence were: being male (OR 1.8), African-American (OR 0.5), and never being married (OR 1.5), and regions outside of the west (Midwest OR 0.7, South OR 0.6, Northeast OR 0.6). Correlates of cannabis abuse and dependence were being male (OR 1.8 and 1.4).

CONCLUSIONS

Lifetime alcohol and cannabis use disorders are highly prevalent in the US population. Men are at higher risk for alcohol and cannabis use disorders. Alcohol use disorders demonstrated specific sociodemographic correlates while marijuana use disorders did not.

Subjective effects for alcohol, tobacco, and marijuana association with cross-drug outcomes

METHODS

The cross-drug relationship of subjective experiences between alcohol, tobacco, and marijuana and problem drug use behaviors were examined. Data were drawn from 3853 individuals between the ages of 11 and 30 years of age participating in the Colorado Center on Antisocial Drug Dependence [CADD]. Subjective experiences were assessed using a 13-item questionnaire that included positive and negative responses for alcohol, tobacco, and marijuana. Lifetime abuse and dependence on these three drugs was assessed using the Composite International Diagnostic Interview, Substance Abuse Module [CIDI-SAM].

RESULTS

Positive and negative subjective experience scales were similar for alcohol, tobacco, and marijuana, although the hierarchical ordering of items differed by drug. Subjective experience scales for each of the three drugs examined correlated significantly, with the strongest relationship being for alcohol and marijuana experiences. Significant associations were identified between how a person experienced a drug and abuse and dependence status for the same or different drug.

CONCLUSION

Cross-drug relationships provide evidence for a common liability or sensitivity towards responding in a similar manner to drugs of abuse within and across different pharmacological classes.

Common and drug-specific genetic influences on subjective effects to alcohol, tobacco and marijuana use

AIM

To examine variation in positive and negative subjective effects to alcohol, tobacco and marijuana and covariation between these three drugs and each effect.

DESIGN

Retrospective self-reports of subjective effects were collected to estimate the genetic and environmental influences and the extent of their specificity across three drugs.

PARTICIPANTS

Data were drawn from 1299 adolescent and young adult same- and opposite sex twin- and sibling-pairs participating in the Colorado Center for Antisocial Drug Dependence (CADD).

SETTING

A large, collaborative, longitudinal study of substance use and antisocial behavior in community and clinical adolescents.

MEASUREMENT

  Subjective effects were assessed using a 13-item questionnaire that included positive and negative responses to alcohol, tobacco and marijuana.

FINDINGS

Heritable influences contributed moderately (additive genetic effects 16-56%) to positive and negative subjective effects to all three drugs and did not differ for males and females. Genetic and environmental contributions to positive and negative subjective effects are largely non-overlapping for tobacco and marijuana. Multivariate genetic modeling indicated that subjective effects to alcohol, tobacco and marijuana share a common, heritable etiology and that drug-specific genetic influences were an important contributor to individual differences in drug response.

CONCLUSIONS

  Results from our genetic analyses suggest that subjective effects to these commonly used and misused drugs are heritable and that the genetic and environmental influences on effects to one drug also influence subjective effects to other drugs.

Subjective effects to marijuana associated with marijuana use in community and clinical subjects

INTRODUCTION

Marijuana is the most commonly used illicit drug among adolescents. Marijuana use induces both psychological and physiological responses, which can be interpreted by an individual in a variety of ways (i.e. subjective effects). We have examined subjective effects in adolescent, young adult community, and clinical populations to determine how patterns of use may be predicted by an individual's subjective experiences with the drug.

METHOD

Participants were community and clinical sample subjects drawn from the Colorado Center of Antisocial Drug Dependence (CADD) and a sample of adjudicated youth from the Denver metropolitan area (aged 11-30). They were evaluated with the Composite International Diagnostic Interview-Substance Abuse Module (CIDI-SAM) and the Lyons battery for subjective effects. Scales for subjective effects were created using Mokken scale analysis. Multivariate linear and logistic regression was used to examine associations between the subjective scales and marijuana outcomes.

RESULTS

Mokken scaling revealed two subjective effects scales, positive and negative. Both scales were significantly positively associated with marijuana abuse or dependence in both the community and clinical sample and regular use in the community sample. The negative scale was negatively associated with past six-month use in the community sample (p<0.05) and clinical sample, after controlling for age and gender effects.

CONCLUSIONS

These findings suggest that diverse subjective experiences with marijuana can be ordered hierarchically and that the resulting short scales can be used in either clinical or community settings. Further, they suggest that the potential for marijuana use problems is related to the type of subjective experience from marijuana exposure.

Association of candidate genes with antisocial drug dependence in adolescents

The Colorado Center For Antisocial Drug Dependence (CADD) is using several research designs and strategies in its study of the genetic basis for antisocial drug dependence in adolescents. This study reports single nucleotide polymorphism (SNP) association results from a targeted gene assay (SNP chip) of 231 primarily Caucasian male probands in treatment with antisocial drug dependence and a matched set of community controls. The SNP chip was designed to assay 1500 SNPs distributed across 50 candidate genes that have had associations with substance use disorders and conduct disorder. There was an average gene-wide inter-SNP interval of 3000 base pairs. After eliminating SNPs with poor signals and low minor allele frequencies, 60 nominally significant associations were found among the remaining 1073 SNPs in 18 of 49 candidate genes. Although none of the SNPs achieved genome-wide association significance levels (defined as p<.000001), two genes probed with multiple SNPs (OPRM1 and CHRNA2) emerged as plausible candidates for a role in antisocial drug dependence after gene-based permutation tests. The custom-designed SNP chip served as an effective and flexible platform for rapid interrogation of a large number of plausible candidate genes.

Association of the neuronal nicotinic receptor beta2 subunit gene (CHRNB2) with subjective responses to alcohol and nicotine

Nicotine addiction and alcohol dependence are highly comorbid disorders that are likely to share overlapping genetic components. We have examined two neuronal nicotinic receptor subunit genes (CHRNA4 and CHRNB2) for possible associations with nicotine and alcohol phenotypes, including measures of frequency of use and measures of initial subjective response in the period shortly after first using the drugs. The subjects were 1,068 ethnically diverse young adults participating in ongoing longitudinal studies of adolescent drug behaviors at the University of Colorado, representing both clinical and community samples. Analysis of six SNPs in the CHRNA4 gene provided modest support for an association with past 6 month use of alcohol in Caucasians (three SNPs with P < 0.08), but no evidence for an association with tobacco and CHRNA4 was detected. However, a SNP (rs2072658) located immediately upstream of CHRNB2 was associated with the initial subjective response to both alcohol and tobacco. This study provides the first evidence for association between the CHRNB2 gene and nicotine- and alcohol-related phenotypes, and suggests that polymorphisms in CHRNB2 may be important in mediating early responses to nicotine and alcohol.

Coronary artery dilatation and aortic outflow tract enlargement in children with unicommissural aortic valves

We evaluated the aortic outflow tract (AOT) and coronary artery dimensions in pediatric patients with unicommissural aortic valves. A retrospective review of an echocardiographic database identified 37 patients with unicommissural aortic valves. A total of 115 echocardiograms were reviewed, and the right coronary artery (RCA), left main coronary artery (LM), left anterior descending coronary artery aortic valve annulus, aortic root, sinotubular junction (STJ), and ascending aorta were measured and z scores determined. The aortic stenosis peak gradient and the amount of aortic regurgitation (AR) were also measured. The RCA diameter (z score, 1.85 +/- 1.8, p = 0.03) and LM diameter (z score, 1.74 +/- 1.47, p = 0.04) are significantly dilated, as are all the AOT measurements: aortic annulus (2.02 +/- 1.9, p = 0.02), aortic root (2.25 +/- 1.9, p = 0.02), STJ (2.22 +/- 1.74, p = 0.01), and ascending aorta (4.38 +/- 2.03, p < 0.001). Longitudinal follow-up showed that there was no significant variation over time in any variable. The AOT measurements were significantly correlated with each other. A trend was found in which an increasing amount of AR gave an increase in AOT measurements. The aortic gradient was not significantly associated with any measurement. Our study population demonstrated significant dilatation of the RCA and LM as well as the AOT. The dilatation of the AOT structures is likely caused by the same mechanism that accounts for the AOT dilatation in patients with bicommissural aortic valves. Dilatation of the coronary arteries may represent an intrinsic abnormality in the vessel wall. Further studies are needed to define possible changes.

Evidence for linkage of nonsyndromic cleft lip with or without cleft palate to a region on chromosome 2

Results from a genome-wide screen of 10 multiplex families ascertained through probands with nonsyndromic cleft lip with or without cleft palate (CL/P) in Mexico, Argentina, and the United States yielded suggestive evidence of linkage to chromosomes 2, 6, 17 and 18. Fine mapping excluded all regions except chromosome 2. Subsequent analysis was performed on the original 10 families plus an additional 16 families using 31 markers on chromosome 2. This analysis showed intriguing evidence of linkage to 2q (Zlr=2.26, empirical P-value=0.028 in a chromosome-wide analysis). Transmission disequilibrium tests also revealed evidence of linkage and disequilibrium for two markers in this region (D2S168 and D2S1400 with P-values=0.022 and 0.006, respectively). A subset of these 26 families provided additional evidence for a susceptibility gene for CL/P on 2q, suggesting that further studies of genes in this region are warranted.

Genetic and environmental risk factors for sagittal craniosynostosis

The authors investigated whether genetic and environmental factors influence risk for sagittal craniosynostosis. Cases were ascertained from craniofacial clinics in the Baltimore-Washington metropolitan region. Controls were recruited from the Johns Hopkins newborn nursery and a large pediatric practice in Baltimore County. Forty-two probands with isolated, nonsyndromic sagittal craniosynostosis born in the mid-Atlantic region were included in this analysis. Controls are infants born in Maryland without any known birth defects (n = 182). Odds ratios (OR) and corresponding 95% confidence intervals (CI) were calculated. Cases were genotyped at several loci implicated in malformation syndromes including craniosynostosis. There were no elevated risks for craniosynostosis related to maternal or paternal smoking or maternal vitamin usage. Case mothers consumed less alcohol (OR = 0.38, 95% CI = 0.17-0.85) and had less education than control mothers ( < 0.001). All cases that were sequenced were negative for mutations at the following genes: exon IIIa 755C->G, (exons IIIa and IIIc,), exon IIIa, and exon 1. These findings suggest that whereas TWIST and the genes are important for syndromic craniosynostosis, they are unlikely to be involved in isolated sagittal craniosynostosis. Parental education and alcohol consumption were associated with sagittal craniosynostosis in this study.

Testing candidate genes for non-syndromic oral clefts using a case-parent trio design

Markers in five candidate genes were examined on 269 case-parent trios ascertained through a child with an isolated, non-syndromic oral cleft (cleft lip, CL; cleft palate, CP; or cleft lip and palate, CLP). Cases and their parents were ascertained through treatment centers in Maryland. Markers at two of the five candidate genes, transforming growth factor beta3 (TGFbeta3) and MSX1, showed consistent evidence of linkage and disequilibrium due to linkage using several statistical tests (e.g., the global chi-square for TGFbeta3 was 21.1 with 12 df, P = 0.03; that for MSX1 was 8.7 with 3 df, P = 0.03). There was little evidence of heterogeneity in the role of TGFbeta3 between different types of oral clefts, but MSX1 did yield marginal evidence for such heterogeneity. MSX1 also showed evidence for interaction between infant's genotype and maternal smoking, giving a likelihood ratio test for heterogeneity between smoker and non-smoker mothers of 7.16 (2 df, P = 0.03). Using a conditional logistic model to test for gene-gene interaction showed no evidence of interaction between TGFbeta3 and MSX1, with both seeming to contribute independently to risk of isolated, non-syndromic oral clefts.

A case-control study of nonsyndromic oral clefts in Maryland

PURPOSE

Isolated, nonsyndromic oral clefts cases (n = 171) and unaffected controls (n = 182) were used to identify both genetic and environmental risk factors.

METHODS

Infants born in Maryland between 1992 to 1998 with an isolated, nonsyndromic oral cleft [cleft lip (CL), cleft lip and palate (CLP), or cleft palate (CP)] were recruited and exposure plus family history data were collected. Controls were unaffected infants. DNA was collected from all cases and their parents, plus controls.

RESULTS

No statistically significant association was found between any of the following: maternal smoking, vitamin use, urinary tract infection, or recreational drug use in either univariate analysis or after adjusting for maternal age and education. More control mothers reported alcohol use during the critical time period of pregnancy (one month before conception through the first trimester) as compared to case mothers. There was a 10-fold increase in risk to siblings of cases as compared to siblings of controls. Markers at four candidate genes were examined: transforming growth factor alpha (TGF alpha), transforming growth factor beta 3 (TGF beta 3), MSX1, and BCL3. Only MSX1 showed significant differences in allele frequencies between CP cases and controls. MSX1 also showed significant evidence of linkage disequilibrium with a susceptibility gene controlling risk for CP.

CONCLUSION

Most environmental risk factors examined here gave little evidence of association with risk to isolated, nonsyndromic oral clefts, although any alcohol consumption seemed protective. MSX1 showed evidence of linkage disequilibrium in both case-control and case-parent trio analysis.

Testing for interaction between maternal smoking and TGFA genotype among oral cleft cases born in Maryland 1992-1996

OBJECTIVE

Infants born in Maryland between June 1992 and June 1996 were used in a case-control study of nonsyndromic oral clefts to test for effects of maternal smoking and a polymorphic genetic marker at the transforming growth factor alpha (TGFA) locus, both of which have been reported to be risk factors for these common birth defects.

DESIGN AND SETTING

Cases were infants with an oral cleft ascertained through three comprehensive treatment centers, with additional ascertainment through a registry of birth defects maintained by the Maryland Health Department. Controls were healthy infants. Medical history information on infants and mothers were collected, along with DNA samples.

PATIENTS, PARTICIPANTS

Among 286 cases contacted (72% ascertainment), there were 192 nonsyndromic isolated oral clefts (106 M; 86 F) available for this case-control study.

MAIN OUTCOME MEASURES

The largest group of 149 Caucasian nonsyndromic cases and 86 controls was used to test for association with maternal smoking and genotype at the Taq1 polymorphism in TGFA.

RESULTS

While this modest sample had limited statistical power to detect gene-environment interaction, there was a significant marginal increase in risk of having an oral cleft if the mother smoked (odds ratio = 1.75, 95% CI = 1.01 to 3.02). We could not demonstrate statistical interaction between maternal smoking and TGFA genotype in this study, however, and the observed increase in the C2 allele among cases was not statistically significant.

CONCLUSIONS

We could not confirm either the reported association between oral clefts and TGFA genotype or its interaction with maternal smoking. However, these data do show an increased risk if the mother smoked during pregnancy, and this effect was greatest among infants with a bilateral cleft and no close family history of clefts.