Genetic Inactivation of CD33 in Hematopoietic Stem Cells to Enable CAR T Cell Immunotherapy for Acute Myeloid Leukemia.

The absence of cancer-restricted surface markers is a major impediment to antigen-specific immunotherapy using chimeric antigen receptor (CAR) T cells. For example, targeting the canonical myeloid marker CD33 in acute myeloid leukemia (AML) results in toxicity from destruction of normal myeloid cells. We hypothesized that a leukemia-specific antigen could be created by deleting CD33 from normal hematopoietic stem and progenitor cells (HSPCs), thereby generating a hematopoietic system resistant to CD33-targeted therapy and enabling specific targeting of AML with CAR T cells. We generated CD33-deficient human HSPCs and demonstrated normal engraftment and differentiation in immunodeficient mice. Autologous CD33 KO HSPC transplantation in rhesus macaques demonstrated long-term multilineage engraftment of gene-edited cells with normal myeloid function. CD33-deficient cells were impervious to CD33-targeting CAR T cells, allowing for efficient elimination of leukemia without myelotoxicity. These studies illuminate a novel approach to antigen-specific immunotherapy by genetically engineering the host to avoid on-target, off-tumor toxicity.

A macaque clonal hematopoiesis model demonstrates expansion of TET2-disrupted clones and utility for testing interventions.

Individuals with age-related clonal hematopoiesis (CH) are at greater risk for hematologic malignancies and cardiovascular diseases. However, predictive preclinical animal models to recapitulate the spectrum of human CH are lacking. Through error-corrected sequencing of 56 human CH/myeloid malignancy genes, we identified natural CH driver mutations in aged rhesus macaques matching genes somatically mutated in human CH, with DNMT3A mutations being the most frequent. A CH model in young adult macaques was generated via autologous transplantation of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated gene-edited hematopoietic stem and progenitor cells (HSPCs), targeting the top human CH genes with loss-of-function (LOF) mutations. Long-term follow-up revealed reproducible and significant expansion of multiple HSPC clones with heterozygous TET2 LOF mutations, compared with minimal expansion of clones bearing other mutations. Although the blood counts of these CH macaques were normal, their bone marrows were hypercellular and myeloid-predominant. TET2-disrupted myeloid colony-forming units isolated from these animals showed a distinct hyperinflammatory gene expression profile compared with wild type. In addition, mature macrophages purified from the CH macaques showed elevated NLRP3 inflammasome activity and increased interleukin-1ß (IL-1ß) and IL-6 production. The model was used to test the impact of IL-6 blockage by tocilizumab, documenting a slowing of TET2-mutated expansion, suggesting that interruption of the IL-6 axis may remove the selective advantage of mutant HSPCs. These findings provide a model for examining the pathophysiology of CH and give insights into potential therapeutic interventions.

Understanding resilience: Lifestyle-based behavioral predictors of mental health and well-being in community-dwelling older adults during the COVID-19 pandemic.

BACKGROUND: Changes in sleep, physical activity and mental health were observed in older adults during early stages of the COVID-19 pandemic. Here we describe effects of the COVID-19 pandemic on older adult mental health, wellbeing, and lifestyle behaviors and explore predictors of better mid-pandemic mental health and wellbeing. METHODS: Participants in the Adult Changes in Thought study completed measures of lifestyle behaviors (e.g., sleep, physical activity) and mental health and wellbeing both pre-pandemic during regular study visits and mid-pandemic via a one-time survey. We used paired t-tests to compare differences in these measures pre- vs. mid-pandemic. Using multivariate linear regression, we further explored demographic, health, and lifestyle predictors of pandemic depressive symptoms, social support, and fatigue. We additionally qualitatively coded free text data from the mid-pandemic survey for related comments. RESULTS: Participants (N = 896) reported significant changes in mental health and lifestyle behaviors at pre-pandemic vs. mid-pandemic measurements (p < 0.0001). Qualitative findings supported these behavioral and wellbeing changes. Being male, never smoking, and lower pre-pandemic computer time and sleep disturbance were significantly associated with lower pandemic depressive symptoms. Being partnered, female, never smoking, and lower pre-pandemic sleep disturbance were associated with higher pandemic social support. Pre-pandemic employment, more walking, less computer time, and less sleep disturbance were associated with less pandemic fatigue. Participant comments supported these quantitative findings, highlighting gender differences in pandemic mental health, changes in computer usage and physical activity during the pandemic, the value of spousal social support, and links between sleep disturbance and mental health and wellbeing. Qualitative findings also revealed additional factors, such as stresses from personal and family health situations and the country's concurrent political environment, that impacted mental health and wellbeing. CONCLUSIONS: Several demographic, health, and lifestyle behaviors appeared to buffer the effects of the COVID-19 pandemic and may be key sources of resilience. Interventions and public health measures targeting men and unpartnered individuals could promote social support resilience, and intervening on modifiable behaviors like sleep quality, physical activity and sedentary activities like computer time may promote resilience to fatigue and depressive symptoms during future community stressor events. Further research into these relationships is warranted.

Real-world clinical, psychosocial and economic burden of atopic dermatitis: Results from a multicountry study.

BACKGROUND: Atopic dermatitis (AD), a relapsing, inflammatory skin disease, is associated with pruritus that can negatively affect patients' quality of life. Understanding the burden of AD is critical for informing and tailoring treatment and disease management to improve patient outcomes. This study characterized global treatment patterns and the clinical, psychosocial and economic burden of moderate-to-severe AD. METHODS: MEASURE-AD was a cross-sectional 28-country study in patients with physician-confirmed moderate-to-severe AD who were either receiving or eligible for systemic therapy for AD. Patients ≥12 years were enrolled between December 2019 and December 2020 while attending routine office or clinic visit. Primary outcomes included Worst Pruritus Numeric Rating Scale (WP-NRS; range: 0-10) and Dermatology Life Quality Index (DLQI; range: 0-30) and Children's DLQI (CDLQI; range: 0-30). Secondary outcomes included physician- and patient-reported clinical, psychosocial and economic burden. RESULTS: Of the 1591 patients enrolled, 1558 (1434 adults and 124 adolescents) fulfilled all patient selection criteria and were included in this analysis. Almost all patients (98.4%) in the total population were using AD medications and more than half (56%) were receiving systemic medication (15% systemic monotherapy). The most used systemic therapies were dupilumab (56.3%), systemic glucocorticoids (18.1%) and methotrexate (16.2%). Mean WP-NRS was 5.3 in the total population, and most patients (≥55%) reported moderate-to-severe pruritus (WP-NRS ≥4). Mean DLQI was 10.8 and mean CDLQI was 9.6. Secondary endpoints demonstrated substantial clinical, psychosocial, and economic burden of disease. Subgroup analysis demonstrated that patients receiving systemic therapy had lower disease burden than those not taking systemic medications. CONCLUSIONS: While systemic therapy lowers overall disease burden, patients with moderate-to-severe AD continue to have substantial multidimensional disease burden and uncontrolled disease. Overall, there is a need for effective disease management, including effective treatments that improve patients' psychosocial outcomes and reduce the economic burden of AD.

Evaluating Board Certification Within the Aesthetic Marketplace.

BACKGROUND: Unlike most health care sectors, patients can select an aesthetic surgery provider without considering insurance coverage. Patients therefore must be able to make informed choices regarding provider selection. Surgeon qualifications are part of the data patients evaluate in their decision making. To characterize the provider landscape that patients face, this study compares the certification requirements of various boards within the aesthetic marketplace. METHODS: Four boards were identified for analysis based on a Google search of "board of plastic surgery": the American Board of Plastic Surgery (ABPS), the American Board of Cosmetic Surgery (ABCS), the American Board of Facial Plastic and Reconstructive Surgery (ABFPRS), and the American Board of Facial Cosmetic Surgery (ABFCS). Information on certification requirements was obtained from each board's official website. RESULTS: ABPS requires that diplomates complete an Accreditation Council for Graduate Medical Education (ACGME)-accredited plastic surgery residency, pass a written and oral examination that includes a case collection, and meet continual standards to maintain certification. ABCS and ABFCS both require an American Academy of Cosmetic Surgery (AACS) cosmetic surgery fellowship and passage of a written and oral examination. Neither board has case collection or continuing certification requirements. ABFPRS requires completion of either an ACGME-accredited otolaryngology or plastic surgery residency. Its examination process includes written and oral components as well as a case log. ABFPRS has enacted continuing certification requirements for diplomates credentialed in 2001 and later. ABPS is the only board that is a member of the American Board of Medical Specialties (ABMS). CONCLUSIONS: ABPS stands apart as the only board within the aesthetic marketplace with rigorous standards for precertification training, demonstrating competency through examinations and case logs, and maintaining certification. Being an ABMS member board also contributes to ABPS being the preeminent organization for identifying physicians who practice safe, effective aesthetic surgery.

Overlapping Surgeries From the Patient's Perspective.

INTRODUCTION: Overlapping surgery (OS) occurs when a single surgeon is concurrently caring for patients in multiple operating rooms (OR) but is present for all critical portions of each surgery. Although this is common practice, most studies have found public disapproval of OS. This study aims to better understand attitudes toward OS of patients who gave informed consent for OS. METHODS: Participant interviews covered topics including trust, OR personnel roles, and attitudes toward OS. Four representative transcripts were distributed among researchers for independent code identification. These were aggregated into a codebook, applied by two coders. Iterative and emergent thematic analyses were done. RESULTS: Twelve participants were interviewed to reach thematic saturation. Three themes shaped how participants felt about OS: trust in their surgeon, worries about OS, and understanding of OR personnel roles. Factors contributing to trust included personal research and the surgeon's experience. Frequently cited concerns were unpredictability of complications during operations and the surgeon's divided attention. Two participants inaccurately understood personnel roles, believing the surgeon did most or all the hands-on work while trainees were observers. Most participants felt a high or neutral level of comfort toward OS and indicated trust as the reason. CONCLUSIONS: In contrast to prior research, this study found that most participants had a neutral or positive view of OS. This suggests that a trusting relationship with their surgeon and informed consent are important factors in increasing comfort for OS. Participants who misunderstood OR roles felt less comfortable toward OS. This highlights an opportunity for patient education on trainee roles.

Prediction and validation of hematopoietic stem and progenitor cell off-target editing in transplanted rhesus macaques.

The programmable nuclease technology CRISPR-Cas9 has revolutionized gene editing in the last decade. Due to the risk of off-target editing, accurate and sensitive methods for off-target characterization are crucial prior to applying CRISPR-Cas9 therapeutically. Here, we utilized a rhesus macaque model to compare the predictive values of CIRCLE-seq, an in vitro off-target prediction method, with in silico prediction (ISP) based solely on genomic sequence comparisons. We use AmpliSeq HD error-corrected sequencing to validate off-target sites predicted by CIRCLE-seq and ISP for a CD33 guide RNA (gRNA) with thousands of off-target sites predicted by ISP and CIRCLE-seq. We found poor correlation between the sites predicted by the two methods. When almost 500 sites predicted by each method were analyzed by error-corrected sequencing of hematopoietic cells following transplantation, 19 off-target sites revealed insertion or deletion mutations. Of these sites, 8 were predicted by both methods, 8 by CIRCLE-seq only, and 3 by ISP only. The levels of cells with these off-target edits exhibited no expansion or abnormal behavior in vivo in animals followed for up to 2 years. In addition, we utilized an unbiased method termed CAST-seq to search for translocations between the on-target site and off-target sites present in animals following transplantation, detecting one specific translocation that persisted in blood cells for at least 1 year following transplantation. In conclusion, neither CIRCLE-seq or ISP predicted all sites, and a combination of careful gRNA design, followed by screening for predicted off-target sites in target cells by multiple methods, may be required for optimizing safety of clinical development.

Patient Perspectives on Selecting an Academic Aesthetic Surgeon: A Qualitative Analysis.

BACKGROUND: Growth of the aesthetic surgery marketplace has increased patient choice in provider selection. This study aimed to characterize how patients choose an aesthetic surgeon, identify knowledge gaps in this decision-making process, and understand why patients select academic aesthetic surgeons. METHODS: A qualitative interview study of aesthetic surgery patients from an academic center was conducted. Purposive sampling maximized representation regarding surgeon, surgery type, and patient demographics. An interview guide was developed in collaboration with content and methodology experts, then refined through pilot testing. Emergent themes were identified using a codebook constructed by grounded theory. RESULTS: Thematic saturation was achieved with 24 patients. When selecting a surgeon, participants valued bedside manner (24 of 24) and past patients' satisfaction (18 of 24). Most participants (16 of 24) ascribed low importance to board certification. Reasons given for choosing an academic practice included the institution's reputation (13 of 24) and the availability of medical records and other specialties if complications arise (8 of 24). Participants demonstrated knowledge gaps regarding medical training and licensure. No participant (0 of 24) was aware that any licensed physician can offer aesthetic surgery, and nearly all participants (23 of 24) expressed discomfort with this. CONCLUSIONS: Patients prioritize subjective elements when selecting an aesthetic surgeon, relying less on objective and meaningful qualifications like board certification and training background. Academic aesthetic practice is valued because of reputation and ability to function as a medical home. Given the lack of public understanding regarding physician training, initiatives promoting transparency are needed to ensure that patients can make safe, informed decisions.

Board Certification in Cosmetic Surgery: An Examination of Online Advertising Practices.

BACKGROUND: Aesthetic surgery patients commonly use online resources to select a surgeon. The American Board of Plastic Surgery is the American Board of Medical Specialties member board that certifies plastic surgeons. The American Board of Cosmetic Surgery (ABCS) provides aesthetic surgery credentials through a non-American Board of Medical Specialties-recognized process. This study examines use of the phrases "plastic surgery" and "plastic surgeon" by ABCS-certified surgeons when advertising online. METHODS: Diplomates of the ABCS were identified from the ABCS Web site. Professional Web sites, Facebook business pages, and Instagram profiles were located by online search. Use of the descriptor "plastic" and ABCS board certification on practice Web sites, Facebook business page categorization, and plastic surgery-related hashtag use on Instagram were recorded. RESULTS: A total of 298 non-American Board of Plastic Surgery-certified ABCS diplomates were included. One hundred eighty-nine (69.5%) categorized their Facebook business page as "plastic surgeon." Within Instagram posts, 123 (57.2%) used #plasticsurgeon, and 172 (80.0%) used #plasticsurgery. On professional Web sites, 90 (30.4%) identified themselves as a "plastic surgeon," 123 (41.6%) characterized their practice as "plastic surgery," and 196 (68.5%) used their ABCS credential to identify as a "board-certified" cosmetic surgeon. CONCLUSIONS: Diplomates of the ABCS frequently use "plastic surgeon" and "plastic surgery" in online advertisements despite a lack of accredited plastic surgery training or board certification. Furthermore, most ABCS diplomates use their ABCS credentials to market themselves as "board-certified" cosmetic surgeons, potentially violating American Medical Association-supported truth in advertising laws in some states and increasing public confusion regarding different board certifications.

Safety of Tibial Half Pins With Circular External Fixation for Foot and Ankle Reconstruction in Patients With Peripheral Neuropathy.

The primary aim of the study was to evaluate the rate of tibial fracture with half pin placement in conjunction with tensioned wires in Ilizarov static external fixator in patients with peripheral neuropathy. Concentric visualization through a rancho cube and careful identification of anterior, posterior, medial, and lateral borders of the tibia, the "perfect circle" technique was used to ensure avoidance of cortical breach. Bivariate analysis was performed comparing the rates of tibia fractures in those who did and did not employ the "perfect circle" technique for placement of tibial half pins; evaluating for demographics, rationale for external fixation use, and postoperative amputation and complication rates. Tibial stress fractures, and early removal of pin/wires from external fixator secondary to breakage both occurred at statistically significant higher rates in patients in which the "perfect circle" technique was not employed (p < .001 and p = .03 respectively). The overall rate of tibia stress fractures was 2.08% (2/96), 0% (0/85) when "perfect circle" technique was used, compared to 18.18% (2/11) when it was not used. This study demonstrates a substantially low rate of tibia stress fractures with half pin use, in contrast to prior literature and should provide foot and ankle surgeons confidence, particularly when appropriate placement is observed in this high-risk population.

Epidemiology of Reported HIV and Other Sexually Transmitted Infections During the COVID-19 Pandemic, New York City.

Early in the coronavirus disease 2019 (COVID-19) crisis, a statewide executive order (PAUSE) severely restricted the movement of New Yorkers from 23 March to 7 June 2020. We used New York City surveillance data for human immunodeficiency virus (HIV), chlamydia, gonorrhea, and syphilis to describe trends in diagnosis and reporting surrounding PAUSE. During PAUSE, the volume of positive HIV/sexually transmitted infection tests, and diagnoses of HIV, chlamydia, gonorrhea, and syphilis declined substantially, reaching a nadir in April before rebounding. Some shifts in characteristics of reported cases were identified.

Trait self-construal, inclusion of others in the self and self-control predict stay-at-home adherence during COVID-19.

To combat the global COVID-19 crisis, governments and health organizations rely on collective cooperation among every ordinary individual to adhere to non-pharmaceutical interventions (NPIs), such physical distancing which includes, as examined in our study, staying at home. Thus, we ask the question: do individual differences in how individuals see themselves as connected to or separated from others (i.e., independent vs. interdependent self-construal) predict their stay-at-home adherence? In an online study (N = 358; 47.1% female, Mage = 40.48; 74.02% White), we measured trait self-construal, inclusion of others in the self (IOS), self-control and likelihood to stay-at-home in various scenarios. Results revealed a significant indirect, sequential effect of self-construal on stay-at-home adherence via IOS and self-control. Specifically, participants with a more accessible interdependent (vs. independent) self-construal reported higher stay-at-home adherence intentions as a consequence of greater IOS and self-control. Theoretical and practical implications are discussed.

Retrocalcaneal Enthesophyte Resection With Functional Lengthening of the Achilles Tendon and Buried Knot Technique: A Case Series.

Retrocalcaneal exostosis can be debilitating and in severe cases, surgical resection is indicated. Complications can arise from surgical resection of the exostosis and reattachment of the Achilles tendon, including irritation of the suture knot, recurrence of the bony prominence, and dehiscence. The use of a buried knot technique with functional lengthening of the Achilles tendon and gastroc-soleal muscle complex can minimize these complications. Complete detachment of the Achilles tendon allows for aggressive and thorough resection of the exostosis and functional lengthening with reattachment. The buried cruciate knot technique allows for firm reattachment with buried knots to prevent soft tissue irritation. A total of fourteen patients (14 limbs) underwent retrocalcaneal enthesophyte resection with functional Achilles tendon lengthening, (8/14) of which had difficultly wearing shoe gear, (10/14) had edema, and (2/14) had erythema preoperatively. Postoperatively, (11/14) of patients returned to full activities and sports, and (11/14) returned to normal shoe gear. Complications included (1/14) of patients with Achilles tendon avulsion and (3/14) of patients with surgical site dehiscence requiring revisional surgery. Overall, this technique helps prevent short-term complications and long-term recurrence due to the functional lengthening mitigating insertional forces on the Achilles tendon.

The impact of aging on primate hematopoiesis as interrogated by clonal tracking.

Age-associated changes in hematopoietic stem and progenitor cells (HSPCs) have been carefully documented in mouse models but poorly characterized in primates and humans. To investigate clinically relevant aspects of hematopoietic aging, we compared the clonal output of thousands of genetically barcoded HSPCs in aged vs young macaques after autologous transplantation. Aged macaques showed delayed emergence of output from multipotent (MP) clones, with persistence of lineage-biased clones for many months after engraftment. In contrast to murine aging models reporting persistence of myeloid-biased HSPCs, aged macaques demonstrated persistent output from both B-cell and myeloid-biased clones. Clonal expansions of MP, myeloid-biased, and B-biased clones occurred in aged macaques, providing a potential model for human clonal hematopoiesis of indeterminate prognosis. These results suggest that long-term MP HSPC output is impaired in aged macaques, resulting in differences in the kinetics and lineage reconstitution patterns between young and aged primates in an autologous transplantation setting.

Do different salience cues compete for dominance in memory over a daytime nap?

Information that is the most salient and important for future use is preferentially preserved through active processing during sleep. Emotional salience is a biologically adaptive cue that influences episodic memory processing through interactions between amygdalar and hippocampal activity. However, other cues that influence the importance of information, such as the explicit direction to remember or forget, interact with the inherent salience of information to determine its fate in memory. It is unknown how sleep-based processes selectively consolidate this complex information. The current study examined the development of memory for emotional and neutral information that was either cued to-be-remembered (TBR) or to-be-forgotten (TBF) across a daytime period including either napping or wakefulness. Baseline memory revealed dominance of the TBR cue, regardless of emotional salience. As anticipated, napping was found to preserve memory overall significantly better than remaining awake. Furthermore, we observed a trending interaction indicating that napping specifically enhanced the discrimination between the most salient information (negative TBR items) over other information. We found that memory for negative items was positively associated with the percentage of SWS obtained during a nap. Furthermore, the magnitude of the difference in memory between negative TBR items and negative TBF items increased with greater sleep spindle activity. Taken together, our results suggest that although the cue to actively remember or intentionally forget initially wins out, active processes during sleep facilitate the competition between salience cues to promote the most salient information in memory.

Telephone-based management of chronic pain in older adults in an integrated care program.

OBJECTIVE: Few studies have explored behavioral strategies for managing chronic pain in older adults. Pain Care Management (PCM) is a telephone-based behavioral intervention for chronic pain. The present study examined chronic pain characteristics among older adults and tested the delivery of PCM as an adjunct to depression and anxiety care management. METHODS: Participants were drawn from a state-sponsored program offering care management services to community members aged 65 and older who were prescribed a psychotropic medication by a primary care provider. Chronic pain information was collected for all participants in the state program (N = 250) and treatment outcome data were collected for a subset with significant chronic pain. Eighty participants with high chronic pain interference were offered PCM and compared to 80 participants with chronic pain who received monitoring only on depression, anxiety, and pain interference outcomes. RESULTS: Chronic pain was identified in 14% of older adults newly prescribed a psychotropic medication. Compared to monitoring only, PCM participants had higher odds of seeing a reduction of 2 or more points in pain interference at 6 months. Pain care management participants' anxiety scores significantly decreased over the study period. CONCLUSIONS: Older adults treated with psychotropic medications often also experience chronic pain that interferes with daily activities. A telephone-based care management intervention is acceptable and feasible with an older community-based population and can lead to improvements in anxiety symptoms and interference from chronic pain. Further research will help to refine interventions that may help improve symptoms and increase functioning with this population.

Routine Use of Low-Molecular-Weight Heparin For Deep Venous Thrombosis Prophylaxis After Foot and Ankle Surgery: A Cost-Effectiveness Analysis.

The purpose of the present study was to determine whether certain foot/ankle surgeries would benefit from the routine use of low-molecular-weight heparin (LMWH) as postoperative deep venous thrombosis prophylaxis. We conducted a formal cost-effectiveness analysis using a decision analytic tree to explore the healthcare costs and health outcomes associated with a scenario of no prophylaxis and a scenario of routine LMWH prophylaxis for 4 weeks. The 2 scenarios were compared for 5 procedures: (1) Achilles tendon repair (ATR), (2) total ankle arthroplasty (TAA), (3) hallux valgus surgery (HVS), (4) hindfoot arthrodesis (HA), and (5) ankle fracture surgery (AFS). The outcomes assessed included short- and long-term costs, quality-adjusted life-years (QALYs), and incremental cost per QALY gained. The costs were evaluated from the healthcare system perspective and are expressed in U.S. dollars at a 2015 price base. In the short term, routine prophylaxis was always associated with greater costs compared with no prophylaxis. For ATR, TAA, HA, and AFS, prophylaxis was associated with slightly better health outcomes; however, the gain in QALYs was minimal compared with the cost of prophylaxis (incremental cost-effectiveness ratio well above $50,000/QALY threshold). For HVS, prophylaxis was associated with both worse health outcomes and greater costs. In the long term, routine prophylaxis was always associated with worse health outcomes and either cost more (HA, AFS, HVS) or saved very little (ATR, TAA). We concluded that policies encouraging the routine use of LMWH after foot/ankle surgery are unlikely to be cost-effective. Decisions to perform prophylaxis should be on a case-by-case basis and should emphasize individual patient risk factors.

Cortical efferents lacking mutant huntingtin improve striatal neuronal activity and behavior in a conditional mouse model of Huntington's disease.

Abnormal electrophysiological activity in the striatum, which receives dense innervation from the cerebral cortex, is believed to set the stage for the behavioral phenotype observed in Huntington's disease (HD), a neurodegenerative condition caused by mutation of the huntingtin (mhtt) protein. However, cortical involvement is far from clear. To determine whether abnormal striatal processing can be explained by mhtt alone (cell-autonomous model) or by mhtt in the corticostriatal projection cell-cell interaction model, we used BACHD/Emx1-Cre (BE) mice, a conditional HD model in which full-length mhtt is genetically reduced in cortical output neurons, including those that project to the striatum. Animals were assessed beginning at 20 weeks of age for at least the next 40 weeks, a range over which presymptomatic BACHD mice become symptomatic. Both open-field and nest-building behavior deteriorated progressively in BACHD mice relative to both BE and wild-type (WT) mice. Neuronal activity patterns in the dorsal striatum, which receives input from the primary motor cortex (M1), followed a similar age progression because BACHD activity changed more rapidly than either BE or WT mice. However, in the M1, BE neuronal activity differed significantly from both WT and BACHD. Although abnormal cortical activity in BE mice likely reflects input from mhtt-expressing afferents, including cortical interneurons, improvements in BE striatal activity and behavior suggest a critical role for mhtt in cortical output neurons in shaping the onset and progression of striatal dysfunction.