Stereotactic radiosurgery for melanoma brain metastases: dose-size response relationship in the era of immunotherapy.

PURPOSE/OBJECTIVE(S): To determine, for intact melanoma brain metastases (MBM) treated with single-fraction stereotactic radiosurgery (SRS), whether planning parameter peripheral dose per lesion diameter (PDLDm, Gy/mm) and lesion control (LC) differs with versus without immunotherapy (IO). MATERIALS/METHODS: We performed a retrospective analysis of patients with intact MBM treated with SRS from 2008 to 2019. Cox-frailty models were constructed to include confounders selected by penalized Cox regression models with a LASSO selector. Interaction effect testing was used to determine whether a significant effect between IO and PDLDm could be demonstrated with respect to LC. RESULTS: The study cohort comprised 67 patients with 244 MBMs treated with SRS (30 patients with 122 lesions treated with both SRS and IO) were included. The logarithm of PDLDm was selected as a predictor of LC (HR 0.307, 95% CI 0.098-0.441), adjusting for IO receipt (HR 0.363, 95% CI 0.108-1.224). Interaction effect testing demonstrated a differential effect of PDLDm by IO receipt, with respect to LC (p = 0.048). Twelve-month LC rates for a 7.5 mm lesion receiving SRS (18 Gy) with IO versus without IO were 87.8% (95% CI 69.0-98.3%) versus 79.8% (95% CI 55.1-93.8%) respectively. CONCLUSION: PDLDm predicted LC in patients with small MBMs treated with single-fraction SRS. We found a differential effect of dose per lesion size and LC by immunotherapy receipt. Future studies are needed to determine whether lower doses of single-fraction SRS afford similarly effective LC for patients with small MBMs receiving immunotherapy.

Racial Variation in the Relationship of Glycemic Control with Fracture Risk in Elderly Patients with Diabetes.

We investigated racial variation in glycemic control (glycated hemoglobin A1c [HbA1c]) with fracture risk in geriatric patients with diabetes. Compared to an HbA1c of 7.0-7.9% [53-63 mmol/mol], HbA1c ≥9.0% [≥75 mmol/mol] was associated with increased fracture risk among Blacks and those of Unknown race only. This increase was attenuated in Blacks after accounting for the relative frequency of patient-provider interaction.

Tumor infiltrating lymphocyte grade in Merkel cell carcinoma: relationships with clinical factors and independent prognostic value.

INTRODUCTION: Surrogate markers of the host immune response are not currently included in AJCC staging for Merkel cell carcinoma (MCC), and have not been consistently associated with clinical outcomes. We performed an analysis of a large national database to investigate tumor infiltrating lymphocyte (TIL) grade as an independent predictor of overall survival (OS) for patients with MCC and to characterize the relationship between TIL grade and other clinical prognostic factors. MATERIAL AND METHODS: The NCDB was queried for patients with resected, non-metastatic MCC with known TIL grade (absent, non-brisk and brisk). Multivariable Cox regression modeling was performed to define TIL grade as a predictor of OS adjusting for other relevant clinical factors. Multinomial, multivariable logistic regression was performed to characterize the relationship between TIL grade and other clinical prognostic factors. Multiple imputation was performed to account for missing data bias. RESULTS: Both brisk (HR 0.55, CI 0.36-0.83) and non-brisk (HR 0.77, CI 0.60-0.98) were associated with decreased adjusted hazard of death relative to absent TIL grade. Adverse clinical factors such as 1-3 positive lymph nodes, lymphovascular invasion (LVI) and immunosuppression were associated with increased likelihood of non-brisk TIL relative to absent TIL grade (p values <.05). Extracapsular extension (ECS) was associated with decreased likelihood of brisk TIL relative to absent TIL grade (p<.05). DISCUSSION: Histopathologic TIL grade was independently predictive for OS in this large national cohort. Significant differences in the likelihood of non-brisk or brisk TIL relative to absent grade were present with regards to LVI, ECS and immune status. TIL grade may be a useful prognostic factor to consider in addition to more granular characterization of TIL morphology and immunophenotype.

Effects of Differential Consequences on Choice Making in Students at Risk for Academic Failure.

Problem behavior can be reduced through choice making and use of preferred instructional activities. However, the opportunity to choose does not imply students are more engaged with instructional activities. The purpose of this study was to evaluate the effects of differential consequences on the on-task behavior of students within the context of teacher versus student selection of instructional activities. Students were exposed to two contingencies (i.e., escape + differential attention vs. escape + physical proximity) across two stimulus events (i.e., teacher vs. student choice of preferred instructional activities) using an alternating-treatments design within an A-B-A-B design. Choice of instructional activities increased on-task behavior during student-choice conditions compared to the teacher-choice conditions, but only when differential attention was provided. Differential attention was also more effective than physical proximity at increasing on-task behavior. Implications for practice and future research are discussed.

Prognostic factors and selection criteria in the retreatment of head and neck cancers.

OBJECTIVES: To determine predictors of treatment selection, outcome, and survival, we examined a cohort of previously irradiated head and neck squamous cell carcinoma (HNSCC) patients. MATERIALS AND METHODS: We retrospectively analyzed 100 patients at our institution who were treated for recurrent or second primary (RSP) HNSCC, focusing on subgroups receiving reirradiation (ReRT) alone and those undergoing surgical salvage (SS) with or without post-operative reirradiation therapy (POReRT). Logistic regression modeling was performed to identify factors predictive of retreatment modality. Cox regression modeling was used to determine prognostic factors for progression free survival (PFS) and overall survival (OS). RESULTS: ReRT alone was less likely in current smokers and neck recurrences, with reirradiation more likely in primary site recurrences. POReRT was significantly more likely in patients with positive surgical margins (PSM), neck dissection, or organ dysfunction. POReRT omission negatively impacted PFS when PSM (HR: 8.894, 95% CI: 1.742-45.403) and perineural invasion (PNI) (HR: 3.391, 95% CI: 1.140-10.089) were present. Tracheostomy was associated with worse OS, but ReRT alone and POReRT improved OS. PSM correlated with worse OS, regardless of whether POReRT was given (HR: 14.260, 95% CI: 2.064-98.547). CONCLUSION: This analysis confirms known factors for predicting outcome and shows nonsmoking status and primary site recurrence as predictors for ReRT alone. POReRT for PSM and PNI improves PFS. Tracheostomy patients are more likely to have ReRT due to acute toxicity not limiting treatment and POReRT improves OS compared to surgery alone. The presence of PSM negatively impacts survival which cannot be overcome by POReRT.

Teaching preschool children to report suspicious packages to adults.

Law enforcement agencies stress that public reporting of terror-related crime is the predominant means for disrupting these actions. However, schools may be unprepared because the majority of the populace may not understand the threat of suspicious materials or what to do when they are found on school grounds. The purpose of this study was to systematically teach preschool children to identify and report suspicious packages across three experiments. In the first experiment, we used multiple exemplar training to teach children to identify the characteristics of safe and unsafe packages. In the second experiment, we taught participants to identify the locations where packages should be considered unsafe. Finally, in the third experiment, we used behavioral skills training to teach participants to avoid touching unsafe packages, leave the area where they were located, and report their discovery to an adult. Results suggest the participants quickly developed these skills. Implications for safety skills in young school children are discussed.

Glycemic control and fracture risk in elderly patients with diabetes.

AIMS: Elderly patients with diabetes are at increased fracture risk. Although long exposure to hyperglycemia may increase fracture risk via adverse effects on bone metabolism, tight glycemic control may increase risk via trauma subsequent to hypoglycemia. We tested the prospective relationship between glycemic control and fracture risk in 10,572 elderly patients (age ≥65) with diabetes. METHODS: Geriatric patients with diabetes were drawn from Vanderbilt University Medical Center's Electronic Health Record. Baseline was defined as age at first HbA1c after the latter of age 65 or ICD 9 code for diabetes. Cox analysis was used to test the relationship of updated mean HbA1c (average HbA1c over follow-up) with time to first fracture since baseline. HbA1c was categorized as follows: <6.5% [<48mmol/mol]; 6.5-6.9% [48-52mmol/mol]; 7-7.9% [53-63mmol/mol]; 8-8.9% [64-74 mmol-mol]; ≥9% [≥75mmol/mol]. The number of BMI measurements was used as a surrogate for relative frequency of outpatient visits, i.e. patient-provider contacts. RESULTS: During follow-up, there were 949 fracture events. HbA1c demonstrated a cubic relationship with fracture risk (p<0.05). In analyses accounting for age, sex, race, and number of BMI measures (a surrogate for patient-provider interaction), compared to an HbA1c of 7-7.9%, HRs (95% CIs) were: HbA1c<6.5% HR=0.97 (0.82-1.14), 6.5-6.9% HR=0.80 (0.66-0.97), 8-8.9% HR=1.13 (0.92-1.40), ≥9% HR=1.19 (0.93-1.54). CONCLUSIONS: An HbA1c of 6.5-6.9% is associated with the lowest risk of fracture in elderly patients with diabetes. Risk associated with an HbA1c ≥9% may be a marker of infrequent patient-provider interaction.

Accessibility, availability, and quality of online information for US radiation oncology residencies.

PURPOSE: Radiation oncology (RO) residency applicants commonly use Internet resources for information on residency programs. The purpose of this study is to assess the accessibility, availability, and quality of online information for RO graduate medical education. METHODS AND MATERIALS: Accessibility of online information was determined by surveying databases for RO residency programs within the Fellowship Residency Electronic Interactive Data Access System (FREIDA) of the American Medical Association, the Accreditation Council for Graduate Medical Education (ACGME), and Google search. As of June 30, 2015, websites were assessed for presence, accessibility, and overall content availability based on a 55-item list of desired features based on 13 program features important to previously surveyed applicants. Quality scoring of available content was performed based on previously published Likert scale variables deemed desirable to RO applicants. Quality score labels were given based on percentage of desired information presented. RESULTS: FREIDA and ACGME databases listed 89% and 98% of program websites, respectively, but only 56% and 52% of links routed to a RO department-specific website, respectively. Google search obtained websites for 98% of programs and 95% of links routed to RO department-specific websites. The majority of websites had program descriptions (98%) and information on staff. However, resident information was more limited (total number [42%], education [47%], previous residents [28%], positions available [35%], contact information [13%]). Based on quality scoring, program websites contained only 47% of desired information on average. Only 13% of programs had superior websites containing 80% or more of desired information. CONCLUSIONS: Compared with Google, the FREIDA and ACGME program databases provide limited access to RO residency websites. The overall information availability and quality of information within RO residency websites varies widely. Applicants and programs may benefit from improved content accessibility and quality from US RO program websites in the residency application process.

Cytochrome P450 1B1 contributes to increased blood pressure and cardiovascular and renal dysfunction in spontaneously hypertensive rats.

PURPOSE: We investigated the contribution of cytochrome P450 (CYP) 1B1 to hypertension and its pathogenesis by examining the effect of its selective inhibitor, 2,4,3',5'-tetramethoxystilbene (TMS), in spontaneously hypertensive rats (SHR). METHODS: Blood pressure (BP) was measured bi-weekly. Starting at 8 weeks, TMS (600 µg/kg, i.p.) or its vehicle was injected daily. At 14 weeks, samples were collected for measurement. RESULTS: TMS reversed increased BP in SHR (207 ± 7 vs. 129 ± 2 mmHg) without altering BP in Wistar-Kyoto rats. Increased CYP1B1 activity in SHR was inhibited by TMS (RLU: aorta, 5.4 ± 0.7 vs. 3.7 ± 0.7; heart, 6.0 ± 0.8 vs. 3.4 ± 0.4; kidney, 411 ± 45 vs. 246 ± 10). Increased vascular reactivity, cardiovascular hypertrophy, endothelial and renal dysfunction, cardiac and renal fibrosis in SHR were minimized by TMS. Increased production of reactive oxygen species and NADPH oxidase activity in SHR, were diminished by TMS. In SHR, TMS reduced increased plasma levels of nitrite/nitrate (46.4 ± 5.0 vs. 28.1 ± 4.1 µM), hydrogen-peroxide (36.0 ± 3.7 vs. 14.1 ± 3.8 µM), and thiobarbituric acid reactive substances (6.9 ± 1.0 vs. 3.4 ± 1.5 µM). Increased plasma levels of pro-inflammatory cytokines and catecholamines, and cardiac activity of extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, c-Src tyrosine kinase, and protein kinase B in SHR were also inhibited by TMS. CONCLUSIONS: These data suggests that increased oxidative stress generated by CYP1B1 contributes to hypertension, increased cytokine production and sympathetic activity, and associated pathophysiological changes in SHR. CYP1B1 could be a novel target for developing drugs to treat hypertension and its pathogenesis.

Serotonin2A/C receptors mediate the aggressive phenotype of TLX gene knockout mice.

Deleting the tailless (TLX) gene in mice produces a highly aggressive phenotype yet to be characterized in terms of heterozygous animals or neurotransmitter mechanisms. We sought to establish pharmacological control over aggression and study the role of serotonin (5-HT)(2A/C) receptors in mediating changes in aggression. We analyzed aggression in mice heterozygous (+/-) or homozygous (-/-) for the TLX gene and wild-types (+/+) using a resident-intruder paradigm. No +/+ mice were aggressive, 36% of +/- TLX and 100% of -/- TLX mice showed aggression. Dose-effect functions were established for clozapine (0.1-1.5mg/kg, ip), ketanserin (0.3-1.25 mg/kg, ip), and (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(±)DOI] (0.5-2.0 mg/kg, ip). Injecting clozapine decreased the frequency and duration of attacks for +/- TLX and -/- TLX mice. Clozapine did not decrease grooming in either +/- TLX or -/- TLX mice but may have increased locomotion for -/- TLX mice. Injecting ketanserin, a 5-HT(2A/C) receptor antagonist, produced differential decreases in frequency and latency to aggression between genotypes and corresponding increases in locomotor behavior. Injecting (±)DOI, a 5-HT(2A/C) receptor agonist, increased the frequency and duration of attacks, decreased the latency to attacks, and decreased locomotion in +/- and -/- TLX mice. Results of the current study suggest aggression displayed by TLX null and heterozygous mice involves 5-HT(2A/C) receptors.

Mortality by race among low-income adults with early-onset insulin-treated diabetes.

OBJECTIVE: To determine if long-term mortality rates in early-onset insulin-treated diabetes differ by race among adults of similar socioeconomic status. RESEARCH DESIGN AND METHODS: A total of 391 (299 African Americans, 92 whites) mostly low-income adults 40-79 years of age with insulin-treated diabetes diagnosed before 30 years of age were recruited from community health centers in the southeast U.S. Cox models were used to estimate hazard ratios (HRs) of all-cause mortality among African Americans compared with whites. Additionally, standardized mortality ratios (SMRs) were used to compare the mortality experience of the individuals with diabetes with both national and general community health center sex- and race-specific population norms. RESULTS: Mean age at diabetes diagnosis and cohort entry, respectively, was 21 and 50 years in African Americans and 19 and 51 years in whites. During an average of 6.7 years of follow-up, 29% of African Americans and 35% of whites died. In multivariable analysis, no significant mortality difference was observed among African Americans compared with whites (HR 0.83 [95% CI 0.53-1.30]; P=0.51). Compared with the race-specific U.S. general population, SMRs for those with diabetes were 5.7 in African Americans and 11.7 in whites. However, when compared with the same source population (i.e., the community health center population), SMRs were 3.5 and 3.7 in African Americans and whites, respectively. CONCLUSIONS: Elevated mortality persists in men and women with long duration of early-onset insulin-treated diabetes, but given survival to 40 years of age and similarly low economic status and access to health care, our data do not suggest a racial disparity in mortality.

Moderating effects of autism on parent views of genetic screening for aggression.

Advances in gene-environment interaction research have revealed genes that are associated with aggression. However, little is known about parent perceptions of genetic screening for behavioral symptoms like aggression as opposed to diagnosing disabilities. These perceptions may influence future research endeavors involving genetic linkage studies to behavior, including proactive approaches for parents to avoid events leading to aggression. The purpose of this study was to solicit the perspectives of parents who have children with autism about screening for genes associated with aggression, compared to responses from those who have children without disabilities and those planning to have children. Parents of children with autism were more likely to support screening and the use of the results to seek treatment if necessary. Results are discussed in the context of surveillance screening and systematic early intervention for behavioral symptoms related to autism. The results may provide insight for clincians, researchers, policymakers, and advocacy groups related to diagnosing and treating aggression in people with autism.

Mortality among low-income African Americans and whites with diabetes.

OBJECTIVE: To estimate mortality rates and risk factors for mortality in a low-socioeconomic status (SES) population of African Americans and whites with diabetes. RESEARCH DESIGN AND METHODS: We determined mortality among African Americans and whites aged 40-79 years with (n = 12,498) and without (n = 49,914) diabetes at entry into a cohort of participants recruited from government-funded community health centers. Multivariable Cox analysis was used to estimate mortality hazard ratios (HRs) (95% CI) among those with versus those without diabetes and among those with diabetes according to patient characteristics. RESULTS: During follow-up (mean 5.9 years), 13.5% of those with and 7.3% of those without diabetes died. All-cause mortality risk was higher among those with versus without diabetes for both African Americans (HR 1.84 [95% CI 1.71-1.99]) and whites (1.80 [1.58-2.04]), although among those with diabetes, mortality was lower among African Americans than whites (0.78 [0.69-0.87]). Mortality risk increased with duration of diabetes and was greater among patients on insulin therapy and reporting histories of cardiovascular disease (CVD), hypertension, and stroke. The HRs associated with these multiple risk factors tended to be similar by sex and race, with the exception of a differentially higher impact of prevalent CVD on mortality among African Americans (interaction P value = 0.03), despite a lower baseline prevalence of CVD. CONCLUSIONS: In this population with similarly low SES and access to health care, strong and generally similar predictors of mortality were identified for African Americans and whites with diabetes, with African Americans at a moderately but significantly lower mortality risk.

Mortality experience of a low-income population with young-onset diabetes.

OBJECTIVE: In young-onset diabetes, insulin therapy status is a rough marker of diabetes type. We describe the mortality experience of a low-income, predominantly minority population with diabetes diagnosed before age 30 years, stratified by insulin therapy. RESEARCH DESIGN AND METHODS: A total of 1,098 adults aged 40-79 years (median 49) diagnosed with diabetes before age 30 years and 49,914 without diabetes were recruited from community health centers. Individuals with diabetes were categorized by insulin therapy at baseline: group A, insulin therapy only; group B, insulin therapy and an oral hypoglycemic agent; and group C, no insulin therapy. Cox models were used to compute hazard ratios (HRs) and 95% CI for cause-specific mortality based on both underlying and contributing causes of death from death certificates. RESULTS: During follow-up (mean 3.9 years), 15.0, 12.5, and 7.3% of groups A, B, and C, respectively, and 4.6% without diabetes died. Compared with individuals without diabetes, HRs (CI) for all-cause mortality were 4.3 (3.4-5.6), 4.2 (2.8-6.3), and 2.0 (1.4-2.8) in groups A, B, and C, respectively. The leading cause of death was renal failure (end-stage renal disease [ESRD]) in group A, ESRD and coronary artery disease (CAD) in group B, and CAD in group C and individuals without diabetes. HRs for these conditions were at least twice as high as the HRs for all-cause mortality, reaching 17.3 (10.2-29.3), 17.9 (8.3-38.7), and 5.1 (2.3-11.7) in groups A, B, and C, respectively, for ESRD. CONCLUSIONS: Excess mortality persists among people with young-onset diabetes of long duration, with ESRD and CAD as the leading contributors to mortality.

Aggression as positive reinforcement in people with intellectual disabilities.

From an applied behavior-analytic perspective, aggression in people with intellectual disabilities is mostly maintained by social reinforcement consequences. However, nonsocial consequences have also been identified in functional assessments on aggression. Behaviors producing their own reinforcement have been labeled "automatic" or "nonsocial" in the behavior-analytic literature, a label that bares a striking resemblance to biobehavioral explanations of reward-seeking behaviors. Biobehavioral studies have revealed that aggression activates the same endogenous brain mechanisms as primary reinforcers like food. Therefore, integrating brain-environment explanations would result in a better understanding of the functional mechanisms associated with nonsocial aggression. The purpose of this paper was to explore aggression as a reinforcing consequence for reinforcement-seeking behaviors in people with intellectual disabilities. First, the literature establishing aggression as reinforcement for arbitrary responding will be reviewed. Next, the reward-related biological process associated with aggression was described. Finally, the paper discusses what might be done to assess and treat aggression maintained by nonsocial reinforcement.

Parametric analysis of thermal preference following sleep deprivation in the rat.

A thermal preference task was used to assess the effects of sleep deprivation on nociceptive behavior using hot and cool stimuli. The thermal preference apparatus allowed male rats to move freely from a hot thermal plate (44.7°C) to an adjacent plate at neutral (33.5°C) or cold temperatures (1.3-11°C). Investigators recorded occupancy on the colder side, frequency of movements between the 2 compartments, and first escape latency from the cold side. Parametric analysis of thermal preference indicated that behavioral allocation was related to temperature ranges previously associated with activation of thermal nociceptors. A 50% occupancy rate was determined from a stimulus-response function identifying 1.3°C vs. 44.7°C as optimal temperatures. This temperature combination was then used to test the effects of sleep deprivation for 48h using the pedestal-over-water method on response allocation to the 2 temperature zones. Sleep deprivation decreased time spent on the cooled plate. Cumulative occupancy indicated differential effects for sleep deprivation with the rats preferring to remain on the hot side vs. the cold side, suggesting that sleep deprivation increased the nociceptive properties of the cold stimulus.

Association between serotonin transporter polymorphisms and problem behavior in adult males with intellectual disabilities.

Research on aggression over the past two decades has focused on gene-environment interaction models to explain the relative contribution of each to this behavioral phenotype in various clinical populations. Recent investigations suggest a link between aggression in people with intellectual disabilities the functionality of the serotonin transporter. The aims in this study were to examine the possible association of the STin2 and/or the 5-HTTLPR serotonin transporter polymorphisms in adult males with and without intellectual disabilities, and to examine the association of these polymorphisms with aggression in people with intellectual disabilities. DNA samples and behavioral records were obtained from adult males with intellectual disabilities, distinguished only by the presence or absence of aggression. No association was found between either transporter polymorphism for aggression. However, the long 5-HTTLPR allele, and not the short allele or the heterozygous state, was associated with the severity of aggression. The association with aggression appears to be genetically complex, suggesting there may be other genes, interactions between genes, and/or environmental relations occasioning aggression in people with intellectual disabilities.

Health and problem behavior among people with intellectual disabilities.

Good health significantly improves a person's quality of life. However, people with intellectual disabilities disproportionately have more health problems than the general population. Further complicating the matter is that people with more severe disabilities often cannot verbalize health complications they are experiencing, which leads to health problems being undiagnosed and untreated. It is plausible these conditions can interact with reinforcement contingencies to maintain problem behavior because of the increased incidence of health problems among people with intellectual disabilities. This paper reviews common health problems influencing problem behavior and reinforcement processes. A clear implication of this review is the need for comprehensive functional assessments of problem behavior involving behavior analysts and health professionals.

Aggression as positive reinforcement in mice under various ratio- and time-based reinforcement schedules.

There is evidence suggesting aggression may be a positive reinforcer in many species. However, only a few studies have examined the characteristics of aggression as a positive reinforcer in mice. Four types of reinforcement schedules were examined in the current experiment using male Swiss CFW albino mice in a resident-intruder model of aggression as a positive reinforcer. A nose poke response on an operant conditioning panel was reinforced under fixed-ratio (FR 8), fixed-interval (FI 5-min), progressive ratio (PR 2), or differential reinforcement of low rate behavior reinforcement schedules (DRL 40-s and DRL 80-s). In the FR conditions, nose pokes were maintained by aggression and extinguished when the aggression contingency was removed. There were long postreinforcement pauses followed by bursts of responses with short interresponse times (IRTs). In the FI conditions, nose pokes were maintained by aggression, occurred more frequently as the interval elapsed, and extinguished when the contingency was removed. In the PR conditions, nose pokes were maintained by aggression, postreinforcement pauses increased as the ratio requirement increased, and responding was extinguished when the aggression contingency was removed. In the DRL conditions, the nose poke rate decreased, while the proportional distributions of IRTs and postreinforcement pauses shifted toward longer durations as the DRL interval increased. However, most responses occurred before the minimum IRT interval elapsed, suggesting weak temporal control of behavior. Overall, the findings suggest aggression can be a positive reinforcer for nose poke responses in mice on ratio- and time-based reinforcement schedules.

Monoamine oxidase a promoter gene associated with problem behavior in adults with intellectual/developmental disabilities.

A functional polymorphism in the promoter of the gene encoding monoamine oxidase A has been associated with problem behavior in various populations. We examined the association of MAOA alleles in adult males with intellectual/developmental disabilities with and without established histories of problem behavior. These data were compared with a gender, ethnicity, and age-matched contrast sample. About 43% (15/35) of adults with intellectual/developmental disabilities and problem behavior possessed the low-efficiency version of the MAOA gene. In comparison, 20% (7/35) of adults with intellectual/developmental disabilities and no problem behavior and 20% (7/35) of the contrast group had the short-allele MAOA polymorphism. Therefore, a common variant in the MAOA gene may be associated with problem behavior in adults with intellectual/developmental disabilities.