Cerebrovascular reactivity measurements using 3T BOLD MRI and a fixed inhaled CO2 gas challenge: Repeatability and impact of processing strategy.

Introduction: Cerebrovascular reactivity (CVR) measurements using blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) are commonly used to assess the health of cerebral blood vessels, including in patients with cerebrovascular diseases; however, evidence and consensus regarding reliability and optimal processing are lacking. We aimed to assess the repeatability, accuracy and precision of voxel- and region-based CVR measurements at 3 T using a fixed inhaled (FI) CO2 stimulus in a healthy cohort. Methods: We simulated the effect of noise, delay constraints and voxel- versus region-based analysis on CVR parameters. Results were verified in 15 healthy volunteers (28.1±5.5 years, female: 53%) with a test-retest MRI experiment consisting of two CVR scans. CVR magnitude and delay in grey matter (GM) and white matter were computed for both analyses assuming a linear relationship between the BOLD signal and time-shifted end-tidal CO2 (EtCO2) profile. Results: Test-retest repeatability was high [mean (95% CI) inter-scan difference: -0.01 (-0.03, -0.00) %/mmHg for GM CVR magnitude; -0.3 (-1.2,0.6) s for GM CVR delay], but we detected a small systematic reduction in CVR magnitude at scan 2 versus scan 1, accompanied by a greater EtCO2 change [±1.0 (0.4,1.5) mmHg] and lower heart rate [-5.5 (-8.6,-2.4] bpm]. CVR magnitude estimates were higher for voxel- versus region-based analysis [difference in GM: ±0.02 (0.01,0.03) %/mmHg]. Findings were supported by simulation results, predicting a positive bias for voxel-based CVR estimates dependent on temporal contrast-to-noise ratio and delay fitting constraints and an underestimation for region-based CVR estimates. Discussion: BOLD CVR measurements using FI stimulus have good within-day repeatability in healthy volunteers. However, measurements may be influenced by physiological effects and the analysis protocol. Voxel-based analyses should be undertaken with care due to potential for systematic bias; region-based analyses are more reliable in such cases.

Milnacipran Ameliorates Executive Function Impairments following Frontal Lobe Traumatic Brain Injury in Male Rats: A Multimodal Behavioral Assessment.

Traumatic brain injuries (TBIs) affect more than 10 million patients annually worldwide, causing long-term cognitive and psychosocial impairments. Frontal lobe TBIs commonly impair executive function, but laboratory models typically focus primarily on spatial learning and declarative memory. We implemented a multi-modal approach for clinically relevant cognitive-behavioral assessments of frontal lobe function in rats with TBI and assessed treatment benefits of the serotonin-norepinephrine reuptake inhibitor, milnacipran (MLN). Two attentional set-shifting tasks (AST) evaluated cognitive flexibility via the rats' ability to locate food-based rewards by learning, unlearning, and relearning sequential rule sets with shifting salient cues. Adult male rats reached stable pre-injury operant AST (oAST) performance in 3-4 weeks, then were isoflurane-anesthetized, subjected to a unilateral frontal lobe controlled cortical impact (2.4 mm depth, 4 m/sec velocity) or Sham injury, and randomized to treatment conditions. Milnacipran (30 mg/kg/day) or vehicle (VEH; 10% ethanol in saline) was administered intraperitoneally via implanted osmotic minipumps (continuous infusions post-surgery, 60 µL/h). Rats had a 10-day recovery post-TBI/Sham before performing light/location-based oAST for 10 days and, subsequently, odor/media-based digging AST (dAST) on the last test day (26-27 days post-injury) before sacrifice. Both AST tests revealed significant deficits in TBI+VEH rats, seen as elevated total trials and errors (p < 0.05), which generally normalized in MLN-treated rats (p < 0.05). This first simultaneous dual AST assessment demonstrates oAST and dAST are sufficiently sensitive and robust to detect subtle attentional and cognitive flexibility executive impairments after frontal lobe TBI in rats. Chronic MLN administration shows promise for attenuation of post-TBI executive function deficits, thus meriting further investigation.

Impaired Glymphatic Function and Pulsation Alterations in a Mouse Model of Vascular Cognitive Impairment.

Large vessel disease and carotid stenosis are key mechanisms contributing to vascular cognitive impairment (VCI) and dementia. Our previous work, and that of others, using rodent models, demonstrated that bilateral common carotid stenosis (BCAS) leads to cognitive impairment via gradual deterioration of the neuro-glial-vascular unit and accumulation of amyloid-ß (Aß) protein. Since brain-wide drainage pathways (glymphatic) for waste clearance, including Aß removal, have been implicated in the pathophysiology of VCI via glial mechanisms, we hypothesized that glymphatic function would be impaired in a BCAS model and exacerbated in the presence of Aß. Male wild-type and Tg-SwDI (model of microvascular amyloid) mice were subjected to BCAS or sham surgery which led to a reduction in cerebral perfusion and impaired spatial learning acquisition and cognitive flexibility. After 3 months survival, glymphatic function was evaluated by cerebrospinal fluid (CSF) fluorescent tracer influx. We demonstrated that BCAS caused a marked regional reduction of CSF tracer influx in the dorsolateral cortex and CA1-DG molecular layer. In parallel to these changes increased reactive astrogliosis was observed post-BCAS. To further investigate the mechanisms that may lead to these changes, we measured the pulsation of cortical vessels. BCAS impaired vascular pulsation in pial arteries in WT and Tg-SwDI mice. Our findings show that BCAS influences VCI and that this is paralleled by impaired glymphatic drainage and reduced vascular pulsation. We propose that these additional targets need to be considered when treating VCI.

McCune-Albright syndrome and type 1 diabetes mellitus: a novel presentation.

McCune-Albright syndrome (MAS) is caused by postzygotic somatic activating mutations of GNAS and is classically characterized by the clinical triad of peripheral precocious puberty, café-au-lait pigmentation, and polyostotic fibrous dysplasia. It can also present with other hyperfunctioning endocrinopathies, including growth hormone excess, hyperprolactinemia, hypercortisolemia, hyperthyroidism, and renal phosphate wasting due to excess fibroblast growth factor 23. We review the clinical, biochemical, radiological, and genetic findings in a 7-year-old girl diagnosed with MAS at age 4 and then with autoimmune type 1 diabetes mellitus at age 7. While MAS is associated with hyperglycemia secondary to growth hormone excess and hypercortisolemia, an association with diabetes mellitus has not been demonstrated. We review the unique presentation of a patient with these two rare conditions.

Transgender men, pregnancy, and the "new" advanced paternal age: A review of the literature.

Transgender men are assigned female at birth, but self-identify as male. Although some transgender men undergo gender-affirming hormonal treatment and/or surgery that preclude pregnancy, many (if not most) retain their female reproductive organs and, as a result, their capacity to become pregnant. Although the visibility of the transgender community has increased, the exposure of healthcare providers to transgender individuals, especially transgender men during pregnancy, as well as research that addresses evidence-based practice remain limited. In this review, we discuss obstetrical issues for transgender men who are ≥35 years old, termed the "new" advanced paternal age. We review preconception care and focus on fertility issues, the impact of stopping gender-affirming hormonal treatment, and age-appropriate health maintenance. We review antepartum and postpartum care, including labor and delivery, monitoring for perinatal depression, contraception, and chest feeding. Finally, we conclude with suggestions for areas for further research and study.

Pallister-Hall Syndrome Presenting in Adolescence.

Pallister-Hall syndrome (PHS) is an extremely rare syndrome of unknown prevalence with autosomal dominant inheritance due to GLI3 gene mutations classically characterized by the presence of a hypothalamic hamartoma and polydactyly. Additional diagnostic criteria include bifid epiglottis, imperforate anus, small nails, hypopituitarism, growth hormone deficiency, and genital hypoplasia. It is typically diagnosed in infancy and early childhood, presenting with seizures and/or precocious puberty due to the hypothalamic hamartoma, and with limb anomalies due to central polydactyly. Our patient had presented with polysyndactyly at birth. However, as this is not uncommon in infants and is usually as part of the sporadic, isolated form of polydactyly, no further work up was done. He then presented at age 16 years with a headache and subjective visual changes, with brain imaging revealing a hypothalamic hamartoma. He did not have a history of seizures or central precocious puberty. Genotyping revealed a pathogenic variant affecting the GLI3 gene. We encourage all clinicians to consider PHS or an associated syndrome with a clinical finding of polydactyly. Further, as the natural history continues to reveal itself, this patient's presentation provides important new data to the broad phenotypic spectrum of PHS.

Chronic treatment with galantamine rescues reversal learning in an attentional set-shifting test after experimental brain trauma.

Approximately 10 million new cases of traumatic brain injury (TBI) are reported each year worldwide with many of these injuries resulting in higher order cognitive impairments. Galantamine (GAL), an acetylcholine esterase inhibitor (AChEI) and positive allosteric modulator of nicotinic acetylcholine receptors (nAChRs), has been reported to ameliorate cognitive deficits after clinical TBI. Previously, we demonstrated that controlled cortical impact (CCI) injury to rats resulted in significant executive function impairments as measured by the attentional set-shifting test (AST), a complex cognitive task analogous to the Wisconsin Card Sorting Test (WCST). We hypothesized that chronic administration of GAL would normalize performance on the AST post-TBI. Isoflurane-anesthetized adult male rats were subjected to moderate CCI (2.8 mm tissue deformation at 4 m/s) or sham injury. Rats were then randomized into one of three treatment groups (i.e., 1 mg/kg GAL, 2 mg/kg GAL, or 1 mL/kg saline vehicle; VEH) or their respective sham controls. GAL or VEH was administered intraperitoneally daily commencing 24 hours post-surgery and until AST testing at 4 weeks post-injury. The AST data revealed significant impairments in the first reversal stage after TBI, seen as increased trials to reach criterion and elevated total errors (p < 0.05). These behavioral flexibility deficits were equally normalized by the administration of both doses of GAL (p < 0.05). Additionally, the higher dose of GAL (2 mg/kg) also significantly reduced cortical lesion volume compared to TBI + VEH controls (p < 0.05). In summary, daily GAL administration provides an efficacious treatment for cognitive deficits and histological recovery after experimental brain trauma. Clinically, these findings are promising considering robust results were attained using a pharmacotherapy already used in the clinic to treat mild dementia.

Reduced TCA cycle rates at high hydrostatic pressure hinder hydrocarbon degradation and obligate oil degraders in natural, deep-sea microbial communities.

Petroleum hydrocarbons reach the deep-sea following natural and anthropogenic factors. The process by which they enter deep-sea microbial food webs and impact the biogeochemical cycling of carbon and other elements is unclear. Hydrostatic pressure (HP) is a distinctive parameter of the deep sea, although rarely investigated. Whether HP alone affects the assembly and activity of oil-degrading communities remains to be resolved. Here we have demonstrated that hydrocarbon degradation in deep-sea microbial communities is lower at native HP (10 MPa, about 1000 m below sea surface level) than at ambient pressure. In long-term enrichments, increased HP selectively inhibited obligate hydrocarbon-degraders and downregulated the expression of beta-oxidation-related proteins (i.e., the main hydrocarbon-degradation pathway) resulting in low cell growth and CO2 production. Short-term experiments with HP-adapted synthetic communities confirmed this data, revealing a HP-dependent accumulation of citrate and dihydroxyacetone. Citrate accumulation suggests rates of aerobic oxidation of fatty acids in the TCA cycle were reduced. Dihydroxyacetone is connected to citrate through glycerol metabolism and glycolysis, both upregulated with increased HP. High degradation rates by obligate hydrocarbon-degraders may thus be unfavourable at increased HP, explaining their selective suppression. Through lab-scale cultivation, the present study is the first to highlight a link between impaired cell metabolism and microbial community assembly in hydrocarbon degradation at high HP. Overall, this data indicate that hydrocarbons fate differs substantially in surface waters as compared to deep-sea environments, with in situ low temperature and limited nutrients availability expected to further prolong hydrocarbons persistence at deep sea.

Heterozygous NPR2 Mutation in Two Family Members with Short Stature and Skeletal Dysplasia.

Endochondral ossification at the level of the growth plate, an essential process involved in longitudinal growth, is regulated by hormonal and local factors including C-type natriuretic peptide and its receptor, natriuretic peptide receptor B. Biallelic loss-of-function mutations in the NPR2 gene, which encodes this receptor, cause acromesomelic dysplasia, Maroteaux type (AMDM), a skeletal dysplasia characterized by severe short stature and disproportionate shortening of limbs. Heterozygous NPR2 mutations have been reported in patients previously classified with idiopathic short stature (ISS). We report the presentation of a 7-year-old girl and her mother with short stature, both of whom were identified with the same NPR2 mutation, and who demonstrated clinical and radiological features consistent with a skeletal dysplasia. We also report the patient's response to recombinant human growth hormone (rhGH) over a 2-year period. We encourage clinicians who evaluate children with ISS to consider genetic testing, particularly when the presentation is associated with features suggestive of a skeletal dysplasia.

High-Quality Draft Genome Sequence of Lactobacillus casei Strain Z11, Isolated from a Human Adult Intestinal Biopsy Sample.

Several Lactobacillus casei strains are used as probiotics. L. casei strain Z11, isolated from a human colon biopsy sample, has been suggested as a probiotic candidate based on promising properties in vitro Here, we present a 2.74-Mbp high-quality draft genome sequence for this strain.

Rare Presentation of Neurofibromatosis and Turner Syndrome in a Pediatric Patient.

Neurofibromatosis type 1 (NF1) is classically defined by the presence of multiple café-au-lait macules as one of the diagnostic criteria. Turner syndrome (TS) can also present with café-au-lait macules along with short stature. Our patient is the fifth reported with both NF1 and TS and the first who has been on growth hormone for short stature associated with TS.

AMP-activated Protein Kinase Deficiency Blocks the Hypoxic Ventilatory Response and Thus Precipitates Hypoventilation and Apnea.

RATIONALE: Modulation of breathing by hypoxia accommodates variations in oxygen demand and supply during, for example, sleep and ascent to altitude, but the precise molecular mechanisms of this phenomenon remain controversial. Among the genes influenced by natural selection in high-altitude populations is one for the adenosine monophosphate-activated protein kinase (AMPK) α1-catalytic subunit, which governs cell-autonomous adaptations during metabolic stress. OBJECTIVES: We investigated whether AMPK-α1 and/or AMPK-α2 are required for the hypoxic ventilatory response and the mechanism of ventilatory dysfunctions arising from AMPK deficiency. METHODS: We used plethysmography, electrophysiology, functional magnetic resonance imaging, and immediate early gene (c-fos) expression to assess the hypoxic ventilatory response of mice with conditional deletion of the AMPK-α1 and/or AMPK-α2 genes in catecholaminergic cells, which compose the hypoxia-responsive respiratory network from carotid body to brainstem. MEASUREMENTS AND MAIN RESULTS: AMPK-α1 and AMPK-α2 deletion virtually abolished the hypoxic ventilatory response, and ventilatory depression during hypoxia was exacerbated under anesthesia. Rather than hyperventilating, mice lacking AMPK-α1 and AMPK-α2 exhibited hypoventilation and apnea during hypoxia, with the primary precipitant being loss of AMPK-α1 expression. However, the carotid bodies of AMPK-knockout mice remained exquisitely sensitive to hypoxia, contrary to the view that the hypoxic ventilatory response is determined solely by increased carotid body afferent input to the brainstem. Regardless, functional magnetic resonance imaging and c-fos expression revealed reduced activation by hypoxia of well-defined dorsal and ventral brainstem nuclei. CONCLUSIONS: AMPK is required to coordinate the activation by hypoxia of brainstem respiratory networks, and deficiencies in AMPK expression precipitate hypoventilation and apnea, even when carotid body afferent input is normal.

Bilateral Sclerosing Stromal Ovarian Tumor in an Adolescent.

Sclerosing stromal tumor of the ovary is a rare, benign, sex cord stromal tumor occurring predominantly in younger women in the 2nd and 3rd decades of life. It typically presents unilaterally with only 2 previously reported cases of bilateral presentation. Common clinical presentations include pelvic or abdominal pain, a mass, or menstrual changes. Although occasionally presenting with hormonal manifestations, virilization as a result of androgen production by the tumor is rare. Here we present an extremely rare case of a sclerosing stromal ovarian tumor in a 14-year-old patient with bilateral presentation and with clinical and biochemical evidence of hyperandrogenemia.

Unbiased and efficient estimation of the volume of the fibroid uterus using the Cavalieri method and magnetic resonance imaging.

The aim of our study was to develop a reliable technique for measuring volume of the fibroid uterus using Magnetic Resonance Imaging. We applied the Cavalieri method and standard calliper technique to measure the volume of the uterus and largest fibroid in 26 patients, and results were compared with "gold-standard" planimetry measurements. We found Cavalieri measurements to be unbiased, while calliper measurements systematically underestimated uterine volume (- 13.2%, P < 10(-5)) and had greater variance. Repeatability was similar for the 2 techniques (standard deviation [SD] = 4.0%-6.9%). Reproducibility of Cavalieri measurements was higher for measurement of uterine (SD = 9.0%) than fibroid volume (SD = 19.1%), whereas the reproducibility of calliper measurements was higher for fibroid (SD = 9.1%) than uterine volume (SD = 15.9%). The additional measurement time for the Cavalieri method was approximately 1 to 2 minutes. In conclusion, the Cavalieri method permits more accurate measurement of uterine and fibroid volumes and is suitable for application in both clinical practice and scientific research.

5α-reductase type 1 modulates insulin sensitivity in men.

CONTEXT: 5α-Reductase (5αR) types 1 and 2 catalyze the A-ring reduction of steroids, including androgens and glucocorticoids. 5α-R inhibitors lower dihydrotestosterone in benign prostatic hyperplasia; finasteride inhibits 5αR2, and dutasteride inhibits both 5αR2 and 5αR1. In rodents, loss of 5αR1 promotes fatty liver. OBJECTIVE: Our objective was to test the hypothesis that inhibition of 5αR1 causes metabolic dysfunction in humans. DESIGN, SETTING, AND PARTICIPANTS: This double-blind randomized controlled parallel group study at a clinical research facility included 46 men (20-85 years) studied before and after intervention. INTERVENTION: Oral dutasteride (0.5 mg daily; n = 16), finasteride (5 mg daily; n = 16), or control (tamsulosin; 0.4 mg daily; n = 14) was administered for 3 months. MAIN OUTCOME MEASURE: Glucose disposal was measured during a stepwise hyperinsulinemic-euglycemic clamp. Data are mean (SEM). RESULTS: Dutasteride and finasteride had similar effects on steroid profiles, with reduced urinary androgen and glucocorticoid metabolites and reduced circulating DHT but no change in plasma or salivary cortisol. Dutasteride, but not finasteride, reduced stimulation of glucose disposal by high-dose insulin (dutasteride by -5.7 [3.2] µmol/kg fat-free mass/min, versus finasteride +7.2 [3.0], and tamsulosin +7.0 [2.0]). Dutasteride also reduced suppression of nonesterified fatty acids by insulin and increased body fat (by 1.6% [0.6%]). Glucose production and glycerol turnover were unchanged. Consistent with metabolic effects of dutasteride being mediated in peripheral tissues, mRNA for 5αR1 but not 5αR2 was detected in human adipose tissue. CONCLUSION: Dual inhibition of 5αRs, but not inhibition of 5αR2 alone, modulates insulin sensitivity in human peripheral tissues rather than liver. This may have important implications for patients prescribed dutasteride for prostatic disease.

Youngest reported patient presenting with an androgen producing sclerosing stromal ovarian tumor.

BACKGROUND: Sclerosing stromal tumors are extremely rare sex cord stromal tumors of the ovary, with approximately 100 cases reported since first described in 1973. These tumors present predominantly in the 2nd and 3rd decades of life, typically present with pelvic/abdominal pain and tenderness, mass, and/or abnormal menses, and with hormonal activity reported predominantly in postmenarchal females. Only 5 cases of these tumors have been reported in premenarchal girls, with age ranging from 7 months to 12 years. Only 2 demonstrated hormonal manifestations, with vaginal bleeding due to hyperestrogenism in the 7 month old, and virilization in an 11-year-old female. CASE: We report a 9-year-old female who was diagnosed with this ovarian tumor, and who presented with virilization. SUMMARY AND CONCLUSION: This report is remarkable as our patient not only was diagnosed with an ovarian tumor that is extremely rare in this age group but is the youngest reported patient with this tumor who presented with virilization.

Quantitative serial MRI of the treated fibroid uterus.

OBJECTIVE: There are no long-term medical treatments for uterine fibroids, and non-invasive biomarkers are needed to evaluate novel therapeutic interventions. The aim of this study was to determine whether serial dynamic contrast-enhanced MRI (DCE-MRI) and magnetization transfer MRI (MT-MRI) are able to detect changes that accompany volume reduction in patients administered GnRH analogue drugs, a treatment which is known to reduce fibroid volume and perfusion. Our secondary aim was to determine whether rapid suppression of ovarian activity by combining GnRH agonist and antagonist therapies results in faster volume reduction. METHODS: Forty women were assessed for eligibility at gynaecology clinics in the region, of whom thirty premenopausal women scheduled for hysterectomy due to symptomatic fibroids were randomized to three groups, receiving (1) GnRH agonist (Goserelin), (2) GnRH agonist+GnRH antagonist (Goserelin and Cetrorelix) or (3) no treatment. Patients were monitored by serial structural, DCE-MRI and MT-MRI, as well as by ultrasound and serum oestradiol concentration measurements from enrolment to hysterectomy (approximately 3 months). RESULTS: A volumetric treatment effect assessed by structural MRI occurred by day 14 of treatment (9% median reduction versus 9% increase in untreated women; P = 0.022) and persisted throughout. Reduced fibroid perfusion and permeability assessed by DCE-MRI occurred later and was demonstrable by 2-3 months (43% median reduction versus 20% increase respectively; P = 0.0093). There was no apparent treatment effect by MT-MRI. Effective suppression of oestradiol was associated with early volume reduction at days 14 (P = 0.041) and 28 (P = 0.0061). CONCLUSION: DCE-MRI is sensitive to the vascular changes thought to accompany successful GnRH analogue treatment of uterine fibroids and should be considered for use in future mechanism/efficacy studies of proposed fibroid drug therapies. GnRH antagonist administration does not appear to accelerate volume reduction, though our data do support the role of oestradiol suppression in GnRH analogue treatment of fibroids. TRIAL REGISTRATION: ClinicalTrials.gov NCT00746031.

Ex vivo water diffusion tensor properties of the fibroid uterus at 7 T and their relation to tissue morphology.

PURPOSE: To investigate the water diffusion tensor properties of ex vivo tissue in the fibroid uterus, including the influence of degeneration, and the relevance of the principal eigenvector orientation to the underlying tissue structure. MATERIALS AND METHODS: Following hysterectomy, high-resolution structural T(2) -weighted and diffusion tensor magnetic resonance imaging (DT-MRI) were performed on nine uteri at 7 T. Mean diffusivity (MD), fractional anisotropy (FA), and principal eigenvector orientation were measured in myometrium and in myxoid and dense tissue in fibroids. Imaging data and measurements of water diffusion parameters were compared with histopathology findings. RESULTS: The nine uteri yielded 23 fibroids. MD was 50% higher in regions of myxoid degeneration compared to dense fibroid tissue (P = 0.001), while myometrium was intermediate in value (dense fibroid tissue, P = 0.15; myxoid degeneration, P = 0.23). FA was lower in dense fibroid tissue than in myometrium (P = 3 × 10(-5) ), but higher than in myxoid tissue (P = 0.003). Principal eigenvector orientation corresponded qualitatively with that of uterine smooth muscle fibers. CONCLUSION: The water diffusion tensor measured ex vivo in the fibroid uterus is a sensitive probe of tissue type, myxoid degeneration, and morphology.

Another unusual presentation of McCune Albright syndrome with fibrous dysplasia, unilateral testicular enlargement, and testicular microlithiasis.

We report on a 9-year-old boy with atypical McCune Albright syndrome who presented with polyostotic fibrous dysplasia, unilateral testicular enlargement without signs of sexual precocity, and bilateral testicular microlithiasis on sonography. This is the first report of a patient with an atypical form of MAS presenting with unilateral testicular enlargement not associated with sexual precocity, and with testicular microlithiasis.

A novel dominant negative mutation of OTX2 associated with combined pituitary hormone deficiency.

CONTEXT: Combined pituitary hormone deficiency (CPHD) is characterized by deficiencies in more than one anterior pituitary hormone. Mutations in developmental factors responsible for pituitary cell specification and gene expression have been found in CPHD patients. OTX2, a bicoid class homeodomain protein, is necessary for both forebrain development and transactivation of the HESX1 promoter, but as of yet, has not been associated with CPHD. OBJECTIVE: The goal of this study was to identify and characterize novel mutations in pituitary specific transcription factors from CPHD patients. DESIGN: Genomic DNA was isolated from patients with hypopituitarism to amplify and sequence eight pituitary specific transcription factors (HESX1, LHX3, LHX4, OTX2, PITX2, POU1F1, PROP1, and SIX6). Characterization of novel mutations is based on structural and functional studies. RESULTS: We describe two unrelated children with CPHD who presented with neonatal hypoglycemia, and deficiencies of GH, TSH, LH, FSH, and ACTH. Magnetic resonance imaging revealed anterior pituitary hypoplasia with an ectopic posterior pituitary. A novel heterozygous OTX2 mutation (N233S) was identified. Wild-type and mutant OTX2 proteins bind equivalently to bicoid binding sites, whereas mutant OTX2 revealed decreased transactivation. CONCLUSIONS: A novel mutation in OTX2 binds normally to target genes and acts as a dominant negative inhibitor of HESX1 gene expression. This suggests that the expression of HESX1, required for spaciotemporal development of anterior pituitary cell types, when disrupted, results in an absent or underdeveloped anterior pituitary with diminished hormonal expression. These results demonstrate a novel mechanism for CPHD and extend our knowledge of the spectrum of gene mutations causing CPHD.