Congenital glottic stenosis as a clinical manifestation of FREM1-associated disorders in a neonate with respiratory distress and aphonia.

A female infant born at 38 weeks and 2 days via induced vaginal delivery was admitted to the neonatal intensive care unit for respiratory distress soon after birth. Noted to have aphonia on examination, the patient underwent direct laryngoscopy and was diagnosed with an anterior glottic web and subglottic stenosis. The patient underwent a genetic workup including whole exome sequencing which resulted in a diagnosis of a FREM1-associated disorder. Congenital glottic webs and subglottic stenoses have not been previously described as clinical manifestations of FREM1-associated disorders.

Familial congenital laryngotracheal stenosis: A systematic review.

BACKGROUND: Congenital laryngotracheal stenosis (CLS) is a rare cause of stridor among newborns. Evidence has shown that several family members can be affected by CLS. Knowledge of the pathophysiology of familial congenital laryngotracheal stenosis (FCLS) will enable more effective therapeutic strategies. OBJECTIVE: To determine the clinical course and outcome of familial congenital laryngotracheal stenosis (FCLS). METHODS: A literature search was conducted over a period of one month (September 2023) by searching several databases to identify studies published from inception to 31st August 2023. RESULTS: Of 256 papers identified, five articles met the inclusion criteria. A total of 17 patients with slight female predominance (59 %) were identified. Familial congenital tracheal stenosis was reported in female twins (100 %). A variety of clinical presentations were listed. An endoscopic airway study was performed on all patients. 64.8 % of the included children were managed surgically. Genetic studies performed on 41 % of children could not locate genetic abnormalities. CONCLUSION: Consanguinity, twin births, and female gender could be predisposing factors for FCLS, although the quality of evidence is low due to the rarity of the condition.

Human Leukocyte Antigen Genotyping of Idiopathic Subglottic Stenosis.

OBJECTIVE: Despite recent scientific inquiry, idiopathic subglottic stenosis (iSGS) remains an enigmatic disease. The consistent demographics of the affected population suggest genetic factors may contribute to disease susceptibility. Given the inflammation observed in the affected proximal airway mucosa, we interrogated disease association with human leukocyte antigen (HLA) polymorphisms. Polymorphisms in the HLA locus have previously been shown to influence individuals' susceptibility to distinct inflammatory diseases. METHODS: High-resolution HLA typing of 37 iSGS patients was compared with 1,242,890 healthy Caucasian controls of European ancestry from the USA National Marrow Donor Program and 281 patients with granulomatosis with polyangiitis (GPA). RESULTS: Complete HLA genotyping of an iSGS population showed no significant associations when compared to a North American Caucasian control population. Unlike GPA patients, iSGS was not associated with allele DPB1*04:01 nor did allele homozygosity correlate with disease severity. CONCLUSIONS: There was not a detectable HLA association observed in iSGS. These results support the concept that iSGS possesses a distinct genetic architecture from GPA. If genetic susceptibility exists in iSGS, it likely lies outside the HLA locus. LEVEL OF EVIDENCE: NA, basic science Laryngoscope, 133:2533-2539, 2023.

RNA Sequencing of Idiopathic Subglottic Stenosis Tissues Uncovers Putative Profibrotic Mechanisms and Identifies a Prognostic Biomarker.

Idiopathic subglottic stenosis (iSGS) is a localized airway disease that almost exclusively affects females. Understanding the molecular mechanisms involved may provide insights leading to therapeutic interventions. Next-generation sequencing was performed on tissue sections from patients with iSGS (n = 22), antineutrophil cytoplasmic antibody-associated vasculitis (AAV; n = 5), and matched controls (n = 9) to explore candidate genes and mechanisms of disease. Gene expression changes were validated, and selected markers were identified by immunofluorescence staining. Epithelial-mesenchymal transition (EMT) and leukocyte extravasation pathways were the biological mechanisms most relevant to iSGS pathogenesis. Alternatively activated macrophages (M2) were abundant in the subepithelium and perisubmucosal glands of the airway in iSGS and AAV. Increased expression of the mesenchymal marker S100A4 and decreased expression of the epithelial marker epithelial cell adhesion molecule (EPCAM) further supported a role for EMT, but to different extents, in iSGS and antineutrophil cytoplasmic antibody-associated subglottic stenosis. In patients with iSGS, high expression of prostate transmembrane protein, androgen induced 1 (PMEPA1), an EMT regulator, was associated with a shorter recurrence interval (25 versus 116 months: hazard ratio = 4.16; P = 0.041; 95% CI, 1.056-15.60). Thus, EMT is a key pathogenetic mechanism of subglottic stenosis in iSGS and AAV. M2 macrophages contribute to the pathogenesis of both diseases, suggesting a shared profibrotic mechanism, and PMEPA1 may be a biomarker for predicting disease recurrence in iSGS.

Idiopathic subglottic stenosis - a familial association and review of practice.

OBJECTIVE: Idiopathic subglottic stenosis describes subglottic stenosis where no inflammatory, traumatic, iatrogenic or other causative aetiology can be identified. The present study aimed to outline our institution's experience of patients diagnosed with idiopathic subglottic stenosis and describe a very rarely reported familial association. METHODS: A retrospective review was conducted of prospectively maintained medical records from 2011 to 2020. Patient clinical, radiological and intra-operative data were reviewed to assess for defined endpoints. RESULTS: Ten patients with idiopathic subglottic stenosis were identified in this series. One familial pairing was identified, with two sisters presenting with the condition. Successful treatment with carbon dioxide laser and dilatation was achieved in most cases. CONCLUSION: Idiopathic subglottic stenosis represents a rare, clinically challenging pathology. Management with endoscopic laser and balloon dilatation is an effective treatment. This paper highlights a very rare familial association, and describes our experience in treating idiopathic subglottic stenosis.

Molecular Mechanisms and Physiological Changes behind Benign Tracheal and Subglottic Stenosis in Adults.

Laryngotracheal stenosis (LTS) is a complex and heterogeneous disease whose pathogenesis remains unclear. LTS is considered to be the result of aberrant wound-healing process that leads to fibrotic scarring, originating from different aetiology. Although iatrogenic aetiology is the main cause of subglottic or tracheal stenosis, also autoimmune and infectious diseases may be involved in causing LTS. Furthermore, fibrotic obstruction in the anatomic region under the glottis can also be diagnosed without apparent aetiology after a comprehensive workup; in this case, the pathological process is called idiopathic subglottic stenosis (iSGS). So far, the laryngotracheal scar resulting from airway injury due to different diseases was considered as inert tissue requiring surgical removal to restore airway patency. However, this assumption has recently been revised by regarding the tracheal scarring process as a fibroinflammatory event due to immunological alteration, similar to other fibrotic diseases. Recent acquisitions suggest that different factors, such as growth factors, cytokines, altered fibroblast function and genetic susceptibility, can all interact in a complex way leading to aberrant and fibrotic wound healing after an insult that acts as a trigger. However, also physiological derangement due to LTS could play a role in promoting dysregulated response to laryngo-tracheal mucosal injury, through biomechanical stress and mechanotransduction activation. The aim of this narrative review is to present the state-of-the-art knowledge regarding molecular mechanisms, as well as mechanical and physio-pathological features behind LTS.

Idiopathic subglottic stenosis in Saskatchewan Hutterite population.

BACKGROUND: By studying the odds of developing idiopathic subglottic stenosis in the isolated and genetically unique Hutterite population, this study sought to strengthen the hypothesis that an underlying genetic predisposition may exist for its development. METHODS: A retrospective chart review examined the medical records of all adult patients treated for idiopathic subglottic stenosis in Saskatchewan between 2008 and 2018. Cases were segregated into Hutterite and non-Hutterite. RESULTS: Four out of 36 cases of idiopathic subglottic stenosis occurred among Hutterites. The odds of a Hutterite developing idiopathic subglottic stenosis are 21.89 times higher than for non-Hutterites. Positive family history was only observed in the Hutterite population. CONCLUSION: The study strengthens the hypothesis that genetics may play a role in the aetiology of idiopathic subglottic stenosis by demonstrating that the genetically and socially unique Hutterites are more likely to develop this rare disease. This study is the first to demonstrate that a specific subpopulation is at a higher risk for developing idiopathic subglottic stenosis.

Persistent Inflammation and Nitric Oxide Dysregulation Are Transcriptomic Blueprints of Subglottic Stenosis.

Subglottic stenosis (SGS) is a recurrent, obstructive, fibroinflammatory disease of the upper airway resulting in severe dyspnea, dysphonia, as well as other potentially fatal complications. Although aberrant inflammation and wound-healing are commonly associated with pathogenesis, the mechanism through which such processes occur and recur in affected patients remains poorly studied. Here we report that transcriptomic profiling of laryngotracheal regions from minimally-invasive mucosal swabs of SGS patients reveals a distinctively pro-inflammatory gene signature. Surprisingly, comparative genomics between SGS patients and mice with direct laryngotracheal injury suggest that SGS patients bear more resemblance to the acute than chronic phase of injury. Furthermore, functional and regulatory network analyses identify neutrophilic involvement through hyper-activation of NF-κB and its downstream inflammasome as a potential master regulator. Interestingly, nitric oxide synthesis was found to be downregulated in SGS patients compared to healthy controls. Thus, SGS represents a state of immunodeficiency whereby defective immune clearance triggers recurrent, long-lasting production of pro-inflammatory cytokines.

Proteomic and Genomic Methylation Signatures of Idiopathic Subglottic Stenosis.

OBJECTIVE: Idiopathic subglottic stenosis (iSGS) is a chronic inflammatory condition that causes dyspnea and affects middle-aged women of White race and non-Latino or Hispanic ethnicity. To better characterize its phenotype and pathogenesis, we assessed the proteomic and genomic methylation signatures of subglottic tissue collected from iSGS patients compared to controls. STUDY DESIGN: Molecular analysis of clinical biospecimens. METHODS: We collected subglottic tissue biopsies from 12 patients during direct laryngoscopy, immediately prior to surgical treatment of iSGS; as well as from 4 age-, sex-, and race/ethnicity-matched control patients undergoing other direct laryngoscopic procedures. We isolated protein and genomic DNA, acquired proteomic data using label-free quantitative mass spectrometry techniques, and acquired genome-wide methylation data using bisulfite conversion and a microarray platform. We compared molecular profiles across the iSGS and control groups, and with respect to clinical course in the iSGS group. Eight of the 12 iSGS patients underwent subsequent blood collection and plasma isolation for further assessment. RESULTS: Proteomic analysis revealed 42 differentially abundant proteins in the iSGS biopsies compared to controls, inferring enrichment of biological pathways associated with early wound healing, innate immunity, matrix remodeling, and metabolism. Proteome-based hierarchical clustering organized patients into two iSGS and one control subgroups. Methylation analysis revealed five hypermethylated genes in the iSGS biopsies compared to controls, including the biotin recycling enzyme biotinidase (BTD). Follow-up analysis showed elevated plasma BTD activity in iSGS patients compared to both controls and published normative data. CONCLUSION: iSGS exhibits distinct proteomic and genomic methylation signatures. These signatures expand current understanding of the iSGS phenotype, support the possibility of disease subgroups, and should inform the direction of future experimental studies. LEVEL OF EVIDENCE: Not applicable Laryngoscope, 131:E540-E546, 2021.

Laryngotracheal Mucosal Surface Expression of Candidate Biomarkers in Idiopathic Subglottic Stenosis.

OBJECTIVES: Idiopathic subglottic stenosis (iSGS) is an inflammatory process leading to fibrosis and narrowing of the laryngotracheal airway. There is variability in patient response to surgical intervention, but the mechanisms underlying this variability are unknown. In this pilot study, we measure expression of candidate targets at the mucosal surface of the subglottis in iSGS patients. We aim to identify putative biomarkers for iSGS that provide insights into the molecular basis of disease progression, yield a gene signature for the disease, and/or predict a response to therapy. STUDY DESIGN: In vitro comparative study of human cells. METHODS: Levels of candidate transcripts and proteins were measured in healthy and stenotic laryngotracheal tissue specimens taken from the mucosal surface in 16 iSGS patients undergoing endoscopic balloon dilation. Pre- and post-operative pulmonary function test and patient reported voice and breathing outcomes were also assessed. Unsupervised clustering was used to define patient subgroups based on expression profile. RESULTS: Pulmonary function and voice and breathing outcome metrics demonstrated significant post-operative improvement. Transcript levels of αSMA, CCL2, COL1A1, COL3A1, FN1, IFNG, and TGFB1 and protein levels of CCL2, IFNG, and IL-6 were significantly upregulated in stenotic as compared to healthy tissues. Marked heterogeneity was observed in the patterns of expression of candidate markers across individuals and tissue types. Patient subgroups defined by expression profile did not show a statistically significant difference in dilation interval. CONCLUSION: Pro-inflammatory and pro-fibrotic pathways are significantly upregulated along the mucosal surface of stenotic laryngotracheal tissues, and CCL2 and IFNG merit further investigation as potential iSGS biomarkers. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:342-349, 2021.

Developmental delay, intellectual disability, short stature, subglottic stenosis, hearing impairment, onychodysplasia of the index fingers, and distinctive facial features: A newly reported autosomal recessive syndrome.

We report on a multiply consanguineous Syrian family where two siblings, a boy and a girl, presented with a compilation of symptoms including developmental delay, severe intellectual disability, absent speech, hearing impairment, short stature, subglottic stenosis, increased length of the palpebral fissures, onychodysplasia of index fingers, scoliosis, genu valgum, and malpositioned toes. Two other individuals from the extended family with similar clinical features are also described. Array-CGH did not reveal any pathological copy number variation. Exome sequencing failed to find any causal variants. Differential diagnoses and the possibility that we might be reporting a hitherto unknown syndrome are discussed.

Familial Aggregation in Idiopathic Subglottic Stenosis.

OBJECTIVE: To evaluate inheritance patterns and define the familial clustering rate of idiopathic subglottic stenosis (iSGS). STUDY DESIGN: Retrospective observational study. SETTING: International multicenter collaborative of >30 tertiary care centers. METHODS: Patients with a clinically confirmed iSGS diagnosis within the North American Airway Collaborative's iSGS1000 cohort consented between 2014 and 2018 were eligible for enrollment. Patient demographics and disease severity were abstracted from the collaborative's iSGS longitudinal registry. Pedigrees of affected families were created. RESULTS: A total of 810 patients with iSGS were identified. Positive family history for iSGS was reported in 44 patients in 20 families. The rate of familial clustering in iSGS is 2.5%. Mean age of disease onset is 42.6 years. Of the 44 patients with familial aggregation of iSGS, 42 were female and 2 were male; 13 were mother-daughter pairs and 2 were father-daughter pairs. There were 3 sister-sister pairs. There was 1 niece-aunt pair and 2 groups of 3 family members. One pedigree demonstrated 2 affected mother-daughter pairs, with the mothers being first-degree paternal cousins. Inheritance is non-Mendelian, and anticipation is present in 11 of 13 (84%) parent-offspring pairs. The mean age of onset between parents (48.4 years) and offspring (36.1 years) was significantly different (P = .016). CONCLUSION: This study quantifies the rate of familial clustering of iSGS at 2.5%. Inheritance is non-Mendelian, and disease demonstrates anticipation. These data suggest that there may be a genetic contribution in iSGS.

Pathologic Fibroblasts in Idiopathic Subglottic Stenosis Amplify Local Inflammatory Signals.

OBJECTIVE: To characterize the phenotype and function of fibroblasts derived from airway scar in idiopathic subglottic stenosis (iSGS) and to explore scar fibroblast response to interleukin 17A (IL-17A). STUDY DESIGN: Basic science. SETTING: Laboratory. SUBJECTS AND METHODS: Primary fibroblast cell lines from iSGS subjects, idiopathic pulmonary fibrosis subjects, and normal control airways were utilized for analysis. Protein, molecular, and flow cytometric techniques were applied in vitro to assess the phenotype and functional response of disease fibroblasts to IL-17A. RESULTS: Mechanistically, IL-17A drives iSGS scar fibroblast proliferation ( P < .01), synergizes with transforming growth factor ß1 to promote extracellular matrix production (collagen and fibronectin; P = .04), and directly stimulates scar fibroblasts to produce chemokines (chemokine ligand 2) and cytokines (IL-6 and granulocyte-macrophage colony-stimulating factor) critical to the recruitment and differentiation of myeloid cells ( P < .01). Glucocorticoids abrogated IL-17A-dependent iSGS scar fibroblast production of granulocyte-macrophage colony-stimulating factor ( P = .02). CONCLUSION: IL-17A directly drives iSGS scar fibroblast proliferation, synergizes with transforming growth factor ß1 to promote extracellular matrix production, and amplifies local inflammatory signaling. Glucocorticoids appear to partially abrogate fibroblast-dependent inflammatory signaling. These results offer mechanistic support for future translational study of clinical reagents for manipulation of the IL-17A pathway in iSGS patients.

Progressive subglottic stenosis in a child with Pallister-Killian syndrome.

Pallister-Killian syndrome (PKS) is rare genetic disorder caused by tetrasomy 12p mosaicism with supernumerary isochromosome 12p that manifests with intellectual disability, craniofacial dysmorphism, and epilepsy. Although PKS presents as a multisystem morphological defect, respiratory system involvement is rare, except for diaphragmatic hernia. We are the first to report a case of PKS with progressive subglottic stenosis. Subglottic stenosis is a potentially lethal condition due to severe respiratory obstruction and difficult intubation; therefore, further accumulation of cases is required to assess the causal link between PKS and subglottic stenosis.

Determining Candidate Single Nucleotide Polymorphisms in Acquired Laryngotracheal Stenosis.

OBJECTIVES/HYPOTHESIS: Despite wide adoption of strategies to prevent injury from prolonged intubation and tracheotomy, acquired laryngotracheal stenosis (ALTS) has not disappeared. ALTS' persistence may be due to patient factors that confer unique susceptibility for some. We sought to identify genetic markers in genes associated with wound healing that could be associated with ALTS. STUDY DESIGN: Case-control study. METHODS: One hundred thirty-eight patients were recruited, 53 patients with ALTS and 85 control patients who underwent intubation or tracheotomy without evidence of ALTS. The patients' DNA was isolated from whole blood. Custom primers were designed, and the TaqMan assay employing allele-specific polymerase chain reaction was used to interrogate single nucleotide polymorphisms (SNPs) rs1799750, rs522616, rs2276109, rs2569190, rs1800469, and rs1024611 of candidate wound healing genes MMP1, MMP3, MMP12, CD14, TGFß1, and MCP1, respectively. A logistic regression model was used to examine the association of candidate gene polymorphisms with the presence or absence of ALTS. RESULTS: All 138 patients were successfully genotyped. No significant association was found between candidate SNPs and development of ALTS in the overall group. However, subgroup analysis within each ethnicity identified SNPs that are associated with ALTS depending upon the ethnic background. CONCLUSIONS: Patient factors such as variations in wound healing due to functional SNPs may shed light on the development of ALTS. There may be a difference in susceptibility to developing ALTS in different ethnic backgrounds. These preliminary findings need to be corroborated in larger population studies. LEVEL OF EVIDENCE: 3b. Laryngoscope, 128:E111-E116, 2018.

The Effect of Human Adipose Tissue-Derived Mesenchymal Stem Cells in Rat's Subglottic Stenosis Model.

OBJECTIVE: Subglottic stenosis remains a clinical challenge. The aim of this study was to evaluate the effect of human adipose tissue-derived mesenchymal stem cells (hAMSCs) in rat model of subglottic stenosis. SUBJECTS AND METHODS: Ninety-six 13-week-old male rats were enrolled in this study. They were divided into 3 groups as normal control (NC) group, a subglottic injury and media injection (SM) group, and a subglottic injury and media-stem cell injection (SMSC) group. The hAMSCs were immediately injected into subglottis after injury. Histologic characteristics of subglottis; the mRNA expressions of interleukin-1ß, cyclooxygenase-2, tumor growth factor-ß and basic fibroblast growth factor; and hAMSCs' survival were evaluated. RESULTS: The hAMSCs survived in the subglottis of the rat until 10 days after implantation. The NC and SMSC groups had a significantly wider subglottic lumen and thinner lamina propria than the SM group at 56 days after injury. Collagen intensity of subglottis was significantly higher in the SM group than in the NC and SMSC groups at 28 days after injury. Gene expression didn't show significant difference between the SM group and the SMSC group. CONCLUSIONS: The hAMSCs injection was found to be helpful for preventing subglottic stenosis in a rat model.

Quantification of Inflammatory Markers in Laryngotracheal Stenosis.

Objectives (1) Develop a novel method for serial assessment of gene and protein expression in laryngotracheal stenosis (LTS). (2) Assess cytokine expression and determine an immunophenotype in LTS. Study Design A matched comparison of endolaryngeal brush biopsy samples from laryngotracheal scar and normal airway. Setting Tertiary care hospital, 2015-2016. Methods Brush biopsy specimens of laryngotracheal scar and normal trachea were obtained from 17 patients with LTS at the time of operating room dilation and were used for protein and RNA extraction. Gene expression of the TH1 cytokine interferon γ (INF-γ), TH2 cytokine interleukin 4 (IL-4), transforming growth factor ß, and collagen 1 (Coll1) was quantified with quantitative real-time polymerase chain reaction. Cytokine analysis was performed with flow cytometry with a cytometric bead array. Results LTS specimens demonstrated a 13.68-fold increase in Coll1 gene expression versus normal ( P < .001, N = 17). Additionally, IL-4 gene expression showed a 3.76-fold increase ( P < .001, N = 17) in LTS scar. When stratified into iatrogenic LTS and idiopathic subglottic stenosis cohorts, INF-γ gene expression was significantly increased in idiopathic subglottic stenosis ( P = .011). Soluble cytokine measurements were below the limit of detection for reliable quantification and thus could not be assessed. Conclusions Brush biopsies from LTS samples can be successfully utilized for RNA extraction and demonstrate the expected increase in Coll1 gene expression associated with LTS. Preliminary gene expression suggests that abnormal collagen production may be mediated by the TH2 cytokine IL-4 and that increased INF-γ expression may represent a key difference between iatrogenic LTS and idiopathic subglottic stenosis. Further analysis of soluble cytokines is needed to confirm these findings.

Severe laryngeal stenosis in newly born twins with 22q11.2 deletion syndrome: A case report.

Chromosome 22q11.2 deletion syndrome is common and presents with a range of clinical features from cardiac malformations to hypocalcemia. Laryngeal anomalies are not a common feature of this syndrome. We describe newly born twins who presented with unexpected severe birth depression secondary to severe type IV glottic webs requiring extensive resuscitation and emergency tracheostomy. They were diagnosed postnatally to have deletion of 22q11.2. The successful resuscitation of these infants at birth was only possible because they were born in a tertiary care hospital. This report shows the critical nature of prenatal diagnosis of 22q11.2 deletion syndrome.

Inflammatory protein expression in human subglottic stenosis tissue mirrors that in a murine model.

OBJECTIVES: We undertook to describe the genetic and protein composition of subglottic stenosis (SGS) by measuring an array of protein expression and messenger RNA levels within human SGS tissue. We also sought to compare this human array to cytokine expression from a murine model of SGS in order to confirm the effective translational nature of our animal model. METHODS: Human granulation tissue from 10 patients with early symptomatic SGS was compared to control bronchus. The expression levels of 24 different cytokines were measured by a Luminex protein assay and real-time polymerase chain reaction. RESULTS: The protein expression in human SGS mirrors that seen in murine SGS. Transforming growth factor ß1, interleukin 1ß, and matrix metalloproteinase 9 were markedly elevated in both human and mouse SGS tissues. The protein array showed a statistically significant elevation in the proinflammatory cytokines tumor necrosis factor α, interleukin 1, granulocyte macrophage colony-stimulating factor, and interferon γ. CONCLUSIONS: This is the first study, to our knowledge, to measure an array of protein expression within human SGS tissue. The expression profile suggests that symptomatic tracheal granulation tissue is mostly within the early inflammatory phase of wound healing and has only begun fibrotic and angiogenic remodeling. This study validates our murine model of SGS, and also helps to define the exact pathways of tissue injury, in the hope of leading to new treatments for this difficult condition.

Translational genomics of acquired laryngotracheal stenosis.

OBJECTIVES/HYPOTHESIS: Acquired laryngotracheal stenosis (ALTS) results from abnormal mucosal wound healing after laryngeal and/or tracheal injury. Patients with ALTS often present late after significant reduction of the airway lumen and onset of symptoms. Motivated by the need for earlier detection of affected patients, we sought to investigate genetic markers for ALTS that would identify susceptible patients. STUDY DESIGN: Pilot Case-Control Study. METHODS: Seventy-six patients were recruited, 40 patients with ALTS and 36 control patients with airway injury but without ALTS. DNA was isolated from whole blood and formalin-fixed paraffin-embedded specimens from patients. Custom primers were designed and the TaqMan assay employing allele-specific polymerase chain reaction was used to interrogate single nucleotide polymorphisms (SNPs): rs2569190, rs1799750, and rs1800469 located in candidate genes CD14, matrix metalloproteinase-1 (MMP-1), and transforming growth factor-ß1 (TGF-ß1), respectively. A logistic regression model was used to examine the association of candidate gene polymorphisms with the presence or absence of ALTS. RESULTS: All 76 patients were successfully genotyped at the three loci of interest by optimizing the genotyping protocol. MMP-1 SNP rs1799750 was most significantly associated with development of ALTS (P = 0.005). CONCLUSION: Identification of SNPs associated with development of ALTS will provide new experimental targets to study wound healing in human subjects. The association found in the current study between ALTS and SNP rs1799750 is being validated in a larger population examining an expanded set of relevant SNPs. Identifying patients with genetic susceptibility to ALTS and poor wound healing in the upper airway will be useful for management of patients after upper-airway injury.