Epidemiology of Pediatric Ocular Surface Inflammatory Diseases in the United States Using the Optum Labs Data Warehouse.

PURPOSE: To benchmark the epidemiologic features of pediatric ocular surface inflammatory diseases (POSID). DESIGN: Retrospective cohort study. PARTICIPANTS: Patients 18 years of age or younger with a medical claim for a diagnosis of POSID in the Optum Labs Data Warehouse between 2007 and 2020. METHODS: Patients with claims of blepharokeratoconjunctivitis (BKC), herpes simplex keratoconjunctivitis (HSK), or vernal keratoconjunctivitis (VKC) were included. Those with less than 6 months of follow-up before the initial diagnosis of POSID were excluded. Odds ratios (ORs) were derived from multivariable logistic regression analyses evaluating the associations between epidemiologic variables and POSID development. MAIN OUTCOME MEASURES: The primary outcome was the estimated prevalence of POSID. Prevalence of POSID subtypes and changes in prevalence over time were also evaluated. RESULTS: Two thousand one hundred sixty-eight patients with POSID were identified from 2018 through 2019, yielding an estimated prevalence of 3.32 per 10 000. The prevalence of POSID was higher among children between 5 and 10 years of age, male children, those of Asian descent, and those living in the Northeast and the West census regions of the United States. The prevalence (per 10 000) of BKC, HSK, and VKC in the same period were 0.59 (95% confidence interval [CI], 0.53-0.65), 0.74 (95% CI, 0.68-0.81), and 1.99 (95% CI, 1.88-2.10), respectively, and significant differences were found in terms of age, sex, racial, ethnic, and regional distributions among the diagnoses. Between 2008 through 2009 and 2018 through 2019, a significant increase in POSID was noted among Asians (from 6.26 [95% CI, 5.28-7.36] to 11.80 [95% CI, 10.40-13.34]) driven by changes in VKC. Multivariable analysis demonstrated that age older than 5 years (OR, 2.57-3.75; 95% CI, 2.17-4.34), male sex (OR, 1.38; 95% CI, 1.26-1.50), Asian descent (OR, 3.12; 95% CI, 2.70-3.60), and Black or African American descent (OR, 1.26; 95% CI, 1.02-1.55) were associated with POSID development. CONCLUSIONS: This study provides an estimated prevalence of POSID and its 3 common subtypes in the United States, with important epidemiologic differences among them. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Unravelling the mechanisms controlling heme supply and demand.

In addition to heme's role as the prosthetic group buried inside many different proteins that are ubiquitous in biology, there is new evidence that heme has substantive roles in cellular signaling and regulation. This means that heme must be available in locations distant from its place of synthesis (mitochondria) in response to transient cellular demands. A longstanding question has been to establish the mechanisms that control the supply and demand for cellular heme. By fusing a monomeric heme-binding peroxidase (ascorbate peroxidase, mAPX) to a monomeric form of green-fluorescent protein (mEGFP), we have developed a heme sensor (mAPXmEGFP) that can respond to heme availability. By means of fluorescence lifetime imaging, this heme sensor can be used to quantify heme concentrations; values of the mean fluorescence lifetime (τMean) for mAPX-mEGFP are shown to be responsive to changes in free (unbound) heme concentration in cells. The results demonstrate that concentrations are typically limited to one molecule or less within cellular compartments. These miniscule amounts of free heme are consistent with a system that sequesters the heme and is able to buffer changes in heme availability while retaining the capability to mobilize heme when and where it is needed. We propose that this exchangeable supply of heme can operate using mechanisms for heme transfer that are analogous to classical ligand-exchange mechanisms. This exquisite control, in which heme is made available for transfer one molecule at a time, protects the cell against the toxic effect of excess heme and offers a simple mechanism for heme-dependent regulation in single-molecule steps.

Recombinant Human Nerve Growth Factor for Pediatric Neurotrophic Keratopathy.

ABSTRACT: A 4-year-old boy presented with right neurotrophic corneal ulcer, lagophthalmos, and facial palsy 8 months after neurosurgery for synchronous brain tumors. Initial treatment with topical antibiotics, topical corticosteroids, lubrication, and lateral tarsorrhaphy successfully treated the corneal epithelial defect; however, the cornea continued to demonstrate diffuse epitheliopathy and a dense stromal opacity and remained insensate on Cochet-Bonnet esthesiometry. After a course of topical cenegermin, central corneal sensation normalized, and the corneal epitheliopathy was markedly improved. Two years after the completion of cenegermin, corneal sensation was maintained; there were no recurrences of epithelial defects, and the stromal opacity had markedly improved. In vivo confocal microscopy (IVCM) demonstrated the presence of subbasal corneal innervation. This report highlights the safety and prolonged effects of cenegermin for the treatment of pediatric iatrogenic neurotrophic keratopathy, as evidenced by the clinical course and IVCM.

Dominant variants in PRR12 result in unilateral or bilateral complex microphthalmia.

Complex microphthalmia is characterized by small eyes with additional abnormalities that may include anterior segment dysgenesis. While many genes are known, a genetic cause is identified in only 4-30% of microphthalmia, with the lowest rate in unilateral cases. We identified four novel pathogenic loss-of-function alleles in PRR12 in families affected by complex microphthalmia and/or Peters anomaly, including two de novo, the first dominantly transmitted allele, as well as the first splicing variant. The ocular phenotypes were isolated with no additional systemic features observed in two unrelated families. Remarkably, ocular phenotypes were asymmetric in all individuals and unilateral (with structurally normal contralateral eye) in three. There are only three previously reported PRR12 variants identified in probands with intellectual disability, neuropsychiatric disorders, and iris anomalies. While some overlap with previously reported cases is seen, nonsyndromic developmental ocular anomalies are a novel phenotype for this gene. Additional phenotypic expansions included short stature and normal development/cognition, each noted in two individuals in this cohort, as well as absence of neuropsychiatric disorders in all. This study identifies new associations for PRR12 disruption in humans and presents a genetic diagnosis resulting in unilateral ocular phenotypes in a significant proportion of cases.

What's trending: a review of social media in ophthalmology.

PURPOSE OF REVIEW: With social media use continuing to increase in popularity, ophthalmologists use social media daily for interactions with patients, colleagues, and the academic community. RECENT FINDINGS: The potential reach of social media is overwhelmingly encouraging, but academic organizations have much work to do in order to compete for viewership on social media platforms, and users need to remain vigilant of easily spread misinformation. Individual ophthalmology practices can tailor their social media presence to attract and educate patients. Using hashtags to supplement the experience of academic conferences has boosted engagement both of attendees and other interested parties. As an effective indicator of the popularity of different subjects in medicine, new studies are leveraging social media for epidemiological models. Finally, social media is emerging as a powerful tool for patient advocacy in ophthalmology. SUMMARY: The accessibility of social media uniquely positions it to educate patients, disseminate public eye health initiatives, and increase the reach of individual physicians. It is also able to enhance the academic experience of conferences, connecting new research colleagues, and is becoming the subject of epidemiologic studies itself. Whether using social media for patient education, research, clinical practice, or patient advocacy, ophthalmologists will find social media an increasingly important workplace contributor.

Precise determination of heme binding affinity in proteins.

Accumulating evidence suggests a new role for cellular heme as a signalling molecule, in which interactions with target proteins are more transient than found with traditionally-defined hemoproteins. To study this role, a precise method is needed for determining the heme-binding affinity (or dissociation constant, Kd). Estimates of Kd are commonly made following a spectrophotometric titration of an apo-protein with hemin. An impediment to precise determination is, however, the challenge in discriminating between the Soret absorbance for the product (holo-protein) and that for the titrant (hemin). An altogether different approach has been used in this paper to separate contributions made by these components to absorbance values. The pure component spectra and concentration profiles are estimated by a multivariate curve-resolution (MCR) algorithm. This approach has significant advantages over existing methods. First, a more precise determination of Kd can be made as concentration profiles for all three components (apo-protein/holo-protein/hemin) are determined and can be simultaneously fitted to a theoretical-binding model. Second, an absorption spectrum for the holo-protein is calculated. This is a unique advantage of MCR and attractive for investigating proteins in which the nature of heme binding has not, hitherto, been characterised because the holo-protein spectrum provides information on the interaction.

Visual Outcomes and Complications of Type I Boston Keratoprosthesis in Children: A Retrospective Multicenter Study and Literature Review.

PURPOSE: To report outcomes and complications of Boston type 1 keratoprosthesis (KPro) implantation in children. DESIGN: Retrospective, multicenter case series. PARTICIPANTS: All children 16 years of age or younger who underwent KPro surgery at 3 ophthalmology centers in Canada between January 2010 and November 2014. METHODS: Records of patients having undergone KPro implantation were reviewed. Data on preoperative characteristics, surgical procedure(s) performed, and postoperative outcomes were collected and analyzed. MAIN OUTCOME MEASURES: Intraoperative and postoperative complications, device retention, and best-corrected visual acuity (BCVA). RESULTS: The KPro was implanted in 11 eyes of 11 patients 0.9 to 15.5 years of age, with 6 being primary corneal procedures. Best-corrected visual acuity recorded before surgery ranged from 20/600 to light perception (LP), and vision in 2 eyes was fix and follow. All patients had been diagnosed with glaucoma and 6 eyes had glaucoma drainage devices (GDDs) inserted before KPro implantation. At last follow-up (mean, 41.8 months; range, 6.5-85.0 months), 2 eyes retained BCVA of 20/400 or better, whereas 5 eyes lost LP. Postoperative complications included retroprosthetic membrane (9 eyes), corneal melt (5 eyes), infectious keratitis (3 eyes), endophthalmitis (3 eyes), GDD erosion (2 eyes), and retinal detachment (5 eyes). The initial KPro was retained in 4 eyes (36.4%). CONCLUSIONS: Boston type 1 keratoprosthesis implantation in children is associated with a substantially higher rate of complications, higher chance of device failure, and worse visual outcomes than observed in adults. In view of these results, the authors do not recommend the use of the KPro in the pediatric population.

A pilot study of stereotactic body radiation therapy (SBRT) after surgery for stage III non-small cell lung cancer.

BACKGROUND: Standard therapy for stage III non-small cell lung cancer with chemotherapy and conventional radiation has suboptimal outcomes. We hypothesized that a combination of surgery followed by stereotactic body radiation therapy (SBRT) would be a safe alternative. METHODS: Patients with stage IIIA (multistation N2) or IIIB non-small cell lung cancer were enrolled from March 2013 to December 2015. The protocol included transcervical extended mediastinal lymphadenectomy (TEMLA) followed by surgical resection, 10 Gy SBRT directed to the involved mediastinum/hilar stations and/or positive surgical margins, and adjuvant systemic therapy. Patients not suitable for anatomic lung resection were treated with 30 Gy to the primary tumor. The primary efficacy end-point was the proportion of patients with grade 3 or higher adverse events (AE) or toxicities. RESULTS: Of 10 patients, 7 patients underwent neoadjuvant chemotherapy. All patients had TEMLA. Nine of 10 patients underwent surgical resection. The remaining patient had an unresectable tumor and received 30 Gy SBRT to the primary lesion. All patients had post-operative SBRT. Median follow-up was 18 months. There were no perioperative mortalities. Six patients had any grade 3 AEs with no grade 4-5 AEs. Of these, 4 were not attributable to radiation. Pulmonary-related grade 3 AEs were experienced by 2 patients. There were no failures within the 10 Gy volume. Overall survival and progression-free survival rates at 2 years were 68% (90% CI 36-86) and 40% (90% CI 16-63), respectively. CONCLUSIONS: In carefully selected patients with locally advanced non-small cell lung cancer, combining surgery with SBRT was well tolerated with no local failure. TRIAL REGISTRATION: ClinicalTrials.gov identifying number NCT01781741 . Registered February 1, 2013.

Control of hypoglossal motoneurones during naturally occurring sleep and wakefulness in the intact, unanaesthetized cat: a field potential study.

The present electrophysiological study was designed to determine the discharge threshold of hypoglossal motoneurones during naturally occurring states of sleep and wakefulness in the intact, unanaesthetized cat. The antidromic field potential, which reflects the net level of membrane excitability of motoneurones and therefore their discharge threshold, was recorded in the hypoglossal nucleus following stimulation of the hypoglossal nerve. The amplitude of the antidromic field potential was larger during wakefulness and non-rapid eye movement (NREM) sleep compared with REM sleep. There was no significant difference in the amplitude of the field potential when wakefulness was compared with NREM sleep (P = 0.103, df = 3, t = 2.324). However, there was a 46% reduction in amplitude during REM sleep compared with NREM sleep (P < 0.001, df = 10, t = 6.421) or wakefulness (P < 0.01, df = 4, t = -4.598). These findings indicate that whereas the excitability of motoneurones that comprise the hypoglossal motor pool is relatively constant during wakefulness and NREM sleep, their excitability is significantly reduced during REM sleep. This state-dependent pattern of control of hypoglossal motoneurones during REM sleep is similar to that reported for motoneurones in other motor nuclei at all levels of the neuraxis. The decrease in the evoked response of hypoglossal motoneurones, which reflects a significant increase in the discharge threshold of individual motoneurones, results in atonia of the lingual and related muscles during REM sleep.

Socioeconomic status and heart failure in Sydney.

BACKGROUND: Socioeconomic disadvantage is associated with an increased risk of developing heart failure and with inferior health outcomes following diagnosis. METHODS: Data for hospitalisations and deaths due to heart failure in the Sydney metropolitan region were extracted from New South Wales hospital records and Australian Bureau of Statistics databases for 1999-2003. Standardised rates were analysed according to patients' residential local government area and correlated with an index of socioeconomic disadvantage. RESULTS: Eight of the 13 local government areas with standardised separation rate ratios significantly higher than all NSW, and those with the six highest standardised separation rate ratios, were in Greater Western Sydney. Rates of heart failure hospitalisations per local government area were inversely correlated with level of socioeconomic status. CONCLUSIONS: Higher rates of heart failure hospitalisations among residents of socioeconomically disadvantaged regions within Sydney highlight the need for strategies to lessen the impact of disadvantage and strategies to improve cardiovascular health.

Vernal keratoconjunctivitis in adults: a narrative review of prevalence, pathogenesis, and management.

Vernal keratoconjunctivitis (VKC) is a chronic, progressive, allergic ocular surface disorder that can lead to sight-threatening complications. VKC occurs primarily in children and generally resolves about the time of puberty; however, case series and retrospective analyses indicate that approximately 10% of patients with VKC are adults, and that a subset of adult cases develop after puberty. Consequently, two age-related variants of VKC have recently been described: early-onset VKC-which manifests during childhood and persists into adult life-and late-onset disease, which emerges de novo after puberty. Although the signs and symptoms of adult and childhood VKC are similar, adult VKC is a long-lasting disease characterized by severe inflammation and increased risk of conjunctival fibrosis, which may place adult patients at higher risk for sight-threatening complications and adverse impacts on daily life. This review discusses the epidemiology, signs, symptoms, immunopathogenesis of adult VKC variants, and highlights current gaps in research and management of patients with this condition.

Co-existence of Neurotrophic Keratopathy in Eyes With Limbal Stem Cell Deficiency.

PURPOSE: To investigate whether neurotrophic keratopathy is present in limbal stem cell deficiency (LSCD), by measuring corneal sensation and characterizing corneal subbasal nerve plexus. DESIGN: Prospective, cross-sectional, case-control comparative study. METHODS: A total of 46 eyes with LSCD and 14 normal eyes were recruited from 2019 to 2022. Corneal sensation was measured using a Cochet-Bonnet esthesiometer, and subbasal nerve plexus was imaged using in vivo confocal microscopy (IVCM) at the central cornea and 4 limbal regions. Subbasal nerve density (SND, number of nerves/mm2), subbasal nerve length (SNL, total length of nerves/mm2) and subbasal nerve branch density (SNBD, number of branches/mm2) were quantified. LSCD was graded to stage 1, 2, and 3 using a previously established staging method consisting of clinical scores, basal cell density, central corneal epithelial thickness, and SNL. RESULTS: The mean (±SD) cornea sensation in the central cornea and limbus were 29.2 ± 21.5 and 33.6 ± 15.1 mm in the LSCD group and 57.6 ± 5.8 and 54.3 ± 4.7 mm in the control group, respectively (all P < .001). In sectoral LSCD, the corneal sensation in the affected regions (29.1 ± 17.6 mm) decreased significantly compared to the unaffected regions (41.4 ± 18.2 mm, P < .001). Central corneal SND, SNL, and SNBD were reduced by 84.6%, 82.6%, and 89.2%, respectively, in LSCD compared to controls (all P < 0.05). The central corneal sensation negatively correlated with the severity of LSCD (rho = -0.64, P < .0001) and positively correlated with SND, SNL, and SNBD (rho = 0.63, 0.66, and 0.56, respectively; all P < .001). CONCLUSIONS: Corneal sensation was reduced in eyes with LSCD. The degree of corneal sensation reduction positively correlated with the severity of LSCD. This finding demonstrated the coexistence of neurotropic keratopathy in LSCD.

Evaluation of 3D tablet-based stereoacuity test ASTEROID in children with normal and abnormal visual acuity.

PURPOSE: To assess the utility of 3D, tablet-based, glasses-free Accurate STEReotest (ASTEROID) in children compared with the Titmus test. METHODS: Children aged 5-13 years were enrolled in a single-center, nonrandomized, observational comparison study and analyzed by age (5-7 vs 8-13 years) and visual acuity (20/25 or better in both eyes vs abnormal). Each participant underwent both the ASTEROID and Titmus stereoacuity tests. Stereoacuity was defined as fine (≤60 arcsec), moderate (61-200 arcsec), coarse (201-1199 arcsec), or very coarse to nil (≥1200 arcsec). Agreement between the tests was assessed using a weighted kappa (κ) statistic based on all four categories. RESULTS: A total of 112 children were included: 28 aged 5-7 with normal visual acuity, 30 aged 5-7 with abnormal visual acuity, 34 aged 8-13 with normal visual acuity, and 20 aged 8-13 with abnormal visual acuity. Mean ASTEROID score was 688 ± 533 arcsec (range, 13-1200 arcsec). Agreement between ASTEROID and Titmus test scores for participants overall was moderate (κ = 0.52). By subgroup, agreement was fair for children 5-7 with abnormal visual acuity (κ = 0.31), moderate for children 5-7 with normal visual acuity (κ = 0.47) and children 8-13 with normal visual acuity (κ = 0.42), and substantial for children 8-13 with abnormal visual acuity (κ = 0.76). Where ASTEROID and Titmus score group varied, ASTEROID score was poorer in 94% (47/50) of cases. CONCLUSIONS: ASTEROID is a digital, tablet-based test that evaluates global stereopsis, does not require glasses, and provides a continuum of scores. Among children, ASTEROID has good agreement with the Titmus test; however, it may be more sensitive at detecting stereovision deficits. Further study is necessary to determine which test is more accurate.

Clinical management, monitoring, and prophylaxis of adverse events of special interest associated with datopotamab deruxtecan.

Antibody drug conjugates (ADCs) are an emerging class of treatments designed to improve efficacy and decrease toxicity compared with other systemic therapies through the selective delivery of cytotoxic agents to tumor cells. Datopotamab deruxtecan (Dato-DXd) is a novel ADC comprising a topoisomerase I inhibitor payload and a monoclonal antibody directed to trophoblast cell-surface antigen 2 (TROP2), a protein that is broadly expressed in several types of solid tumors. Dato-DXd is being investigated across multiple solid tumor indications. In the ongoing, first-in-human TROPION-PanTumor01 phase I study (ClinicalTrials.gov: NCT03401385), encouraging and durable antitumor activity and a manageable safety profile was demonstrated in patients with advanced/metastatic hormone receptor-positive/human epidermal growth factor receptor2-negative breast cancer (HR+/HER2- BC), triple-negative breast cancer (TNBC), and non-small cell lung cancer (NSCLC). Improved understanding of the adverse events (AEs) that are associated with Dato-DXd and their optimal management is essential to ensure safe and successful administration. Interstitial lung disease/pneumonitis, infusion-related reactions, oral mucositis/stomatitis, and ocular surface events have been identified as AEs of special interest (AESIs) for which appropriate prevention, monitoring, and management is essential. This article summarizes the incidence of AESIs among patients with HR+/HER2- BC, TNBC, and NSCLC reported in TROPION-PanTumor01. We report our recommendations for AESI prophylaxis, early detection, and management, using experience gained from treating AESIs that occur with Dato-DXd in clinical trials.

Definition and Diagnostic Criteria for Pediatric Blepharokeratoconjunctivitis.

Importance: Pediatric blepharokeratoconjunctivitis (PBKC) is a chronic, sight-threatening inflammatory ocular surface disease. Due to the lack of unified terminology and diagnostic criteria, nonspecific symptoms and signs, and the challenge of differentiation from similar ocular surface disorders, PBKC may be frequently unrecognized or diagnosed late. Objective: To establish a consensus on the nomenclature, definition, and diagnostic criteria of PBKC. Design, Setting, and Participants: This quality improvement study used expert panel and agreement applying the non-RAND modified Delphi method and open discussions to identify unified nomenclature, definition, and definitive diagnostic criteria for PBKC. The study was conducted between September 1, 2021, and August 14, 2022. Consensus activities were carried out through electronic surveys via email and online virtual meetings. Results: Of 16 expert international panelists (pediatric ophthalmologists or cornea and external diseases specialists) chosen by specific inclusion criteria, including their contribution to scientific leadership and research in PBKC, 14 (87.5%) participated in the consensus. The name proposed was "pediatric blepharokeratoconjunctivitis," and the agreed-on definition was "Pediatric blepharokeratoconjunctivitis is a frequently underdiagnosed, sight-threatening, chronic, and recurrent inflammatory eyelid margin disease associated with ocular surface involvement affecting children and adolescents. Its clinical spectrum includes chronic blepharitis, meibomitis, conjunctivitis, and corneal involvement ranging from superficial punctate keratitis to corneal infiltrates with vascularization and scarring." The diagnostic criteria included 1 or more suggestive symptoms accompanied by clinical signs from 3 anatomical regions: the eyelid margin, conjunctiva, and cornea. For PBKC suspect, the same criteria were included except for corneal involvement. Conclusions and Relevance: The agreements on the name, definition, and proposed diagnostic criteria of PBKC may help ophthalmologists avoid diagnostic confusion and recognize the disease early to establish adequate therapy and avoid sight-threatening complications. The diagnostic criteria rely on published evidence, analysis of simulated clinical cases, and the expert panel's clinical experience, requiring further validation with real patient data analysis.

Sinoatrial Node Dose Is Associated With Worse Survival in Patients Undergoing Definitive Stereotactic Body Radiation Therapy for Central Lung Cancers.

PURPOSE: Our purpose was to evaluate the clinical consequences of sinoatrial node (SAN) and atrioventricular node (AVN) irradiation in patients undergoing stereotactic body radiation therapy (SBRT) for central non-small cell lung cancer (NSCLC) tumors. METHODS AND MATERIALS: A single-institutional retrospective review of patients with primary NSCLC undergoing definitive SBRT for centrally located thoracic tumors from February 2007 to December 2021 was performed. The SAN and AVN were contoured in accordance with a published contouring atlas, and the maximum dose (Dmax) and mean dose (Dmean) for each structure were calculated. Sequential log rank testing between the 50th and 90th percentiles was used to identify potential cutoff values for the corresponding dosimetric parameters and overall survival. RESULTS: Among 93 eligible patients, the median age was 72.5 years (IQR, 66.6-78.3), and median follow-up was 32.4 months (IQR, 13.0-49.6). The median SAN Dmax and Dmean were 95 cGy (range, 9-5394) and 58 cGy (range, 7-3168), respectively. The median AVN Dmax and Dmean were 45 cGy (range, 4-2121) and 34 cGy (range, 3-1667), respectively. Candidate cutoff values for SAN Dmax and Dmean were 1309 and 836 cGy, respectively. No associations between AVN parameters and survival outcomes were identified. Upon multivariate Cox regression, the SAN Dmax cutoff (hazard ratio [HR], 2.03 [1.09-3.79]; P = .026) and SAN Dmean cutoff (HR, 2.22 [1.20-4.12]; P = .011) were significantly associated with overall survival. For noncancer-associated survival, the SAN Dmax cutoff trended toward significance (HR, 2.02 [0.89-4.57]; P = .092), and the SAN Dmean cutoff remained significantly associated (HR, 2.34 [1.05-5.18]; P = .037). CONCLUSIONS: For patients undergoing SBRT for NSCLC, SAN Dmax and Dmean were significantly associated with worse overall survival using cut-off values of 1309 and 836 cGy, respectively. Further studies examining the effect of SAN irradiation during SBRT are warranted.

Functional interaction between SNPs and microsatellite in the transcriptional regulation of insulin-like growth factor 1.

A CA-repeat microsatellite in insulin-like growth factor 1 (IGF1) promoter was associated with interindividual variation of circulating IGF1 level. Previously, we reported that such association was due to variation of haplotype unit in a linkage disequilibrium block composed of microsatellite and single-nucleotide polymorphisms (SNPs), suggesting the presence of an interaction between them. In this study, reporter assays were performed to investigate the regulatory effect and interaction of genetic variants on gene expression. We used an in vitro system to compare the transcriptional activities of haplotypes (rs35767:T>C, the CA-repeat microsatellite, rs5742612:T>C, and rs2288377:T>A) in evolutionarily conserved region of IGF1 promoter. In haplotype C-T-T, a longer microsatellite had a lower transcriptional activity (17.6 ± 2.4-fold for 17 repeats and 8.3 ± 1.1-fold for 21 repeats), whereas in haplotype T-C-A, such trend could not be observed, as the microsatellite with 21 repeats had the highest transcriptional activity (17.5 ± 2.3-fold). Because the microsatellite and SNPs affected the transcriptional activity of each other, there may be an interaction between them in the regulation of IGF1 expression. For the first time, we demonstrated that a noncoding microsatellite polymorphism could act as a functional unit and interact with SNPs in the regulation of transcription in human genome.