Angiotensin converting enzyme (ACE) gene polymorphism in sarcoidosis in relation to associated autoimmune diseases

Re-evaluating serum angiotensin-converting enzyme in sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology, which mainly affects the lungs and lymph nodes, as well as extrapulmonary organs. Its incidence, and prevalence rate, and disease course largely vary with regions and populations globally. The clinical manifestations of sarcoidosis depend on the affected organs and the degree of severity, and the diagnosis is mainly based on serum biomarkers, radiographic, magnetic resonance, or positron emission tomography imaging, and pathological biopsy. Noncaseating granulomas composing T cells, macrophages, epithelioid cells, and giant cells, were observed in a pathological biopsy, which was the characteristic pathological manifestation of sarcoidosis. Angiotensin-converting enzyme (ACE) was first found in the renin-angiotensin-aldosterone system. Its main function is to convert angiotensin I (Ang I) into Ang II, which plays an important role in regulating blood pressure. Also, an ACE insertion/deletion polymorphism exists in the human genome, which is involved in the occurrence and development of many diseases, including hypertension, heart failure, and sarcoidosis. The serum ACE level, most commonly used as a biomarker in diagnosing sarcoidosis, in patients with sarcoidosis increases. because of epithelioid cells and giant cells of sarcoid granuloma expressing ACE. Thus, it serves as the most commonly used biomarker in the diagnosis of sarcoidosis and also aids in analyzing its therapeutic effect and prognosis in patients with sarcoidosis.

Whole Exome Sequencing Identified Two Single Nucleotide Polymorphisms of Human Leukocyte Antigen-DRB5 in Familial Sarcoidosis in China

BACKGROUND

Sarcoidosis is a multisystem granulomatous disorder whose etiology is related to genetic and immunological factors. Familial aggregation and ethnic prevalence suggest a genetic predisposition and inherited susceptibility to sarcoidosis.

OBJECTIVE

This study aimed to identify suspected risk loci for familial sarcoidosis patients.

METHODS

We conducted whole exome sequencing on two sarcoidosis patients and five healthy family members in a Chinese family for a case-control study. The two sarcoidosis patients were siblings who showed chronic disease.

RESULTS

The Gene Ontology results showed single nucleotide polymorphisms in three genes, including human leukocyte antigen (HLA)-DRB1, HLA-DRB5, and KIR2DL4, associated with both 'antigen processing and presentation' and 'regulation of immune response.' Sanger sequencing verified two nonsynonymous mutations in HLA-DRB5 (rs696318 and rs115817940) located on 6p21.3 in the major histocompatibility complex (MHC) class II beta 1 region. The structural model simulated on Prot- Param protein analysis by the Expert Protein Analysis System predicted that the hydropathy index changed at two mutation sites (rs696318: p.F96L, -1.844 to -1.656 and rs115817940: p.T106N, -0.322 to -0.633), which indicated the probability of changes in peptide-binding selectivity.

CONCLUSION

Our results indicated that two nonsynonymous mutations of HLA-DRB5 have been identified in two sarcoidosis siblings, while their healthy family members do not have the mutations. The two HLA-DRB5 alleles may influence genetic susceptibility and chronic disease progression through peptide mutations on the MHC class II molecule among the two affected family members.

Autoimmunity in sarcoidosis: the tip of the Iceberg

Sarcoidosis is a mysterious condition with an etiology that has to date eluded explanation. Innumerable clinical and serological organ- and non-organ-specific autoimmune associations have been reported. Many of the associated conditions are life-threatening but easily manageable if diagnosed early. Due to the long latency that precedes the clinical onset of autoimmune diseases, it is prudent to ensure a long follow-up and a broad viewing perspective while maintaining a high index of suspicion when viewing the autoimmunity iceberg in sarcoidosis.

The Immunogenetics of Vitiligo: An Approach Toward Revealing the Secret of Depigmentation

Vitiligo is a hypomelanotic skin disease and considered to be of autoimmune origin due to breaching of immunological self-tolerance, resulting in inappropriate immune responses against melanocytes. The development of vitiligo includes a strong heritable component. Different strategies ranging from linkage studies to genome-wide association studies are used to explore the genetic factors responsible for the disease. Several vitiligo loci containing the respective genes have been identified which contribute to vitiligo and genetic variants for some of the genes are still unknown. These genes include mainly the proteins that play a role in immune regulation and a few other genes important for apoptosis and regulation of melanocyte functions. Despite the available data on genetic variants and risk alleles which influence the biological processes, only few immunological pathways have been found responsible for all ranges of severity and clinical manifestations of vitiligo. However, studies have concluded that vitiligo is of autoimmune origin and manifests due to complex interactions in immune components and their inappropriate response toward melanocytes. The genes involved in the immune regulation and processing the melanocytes antigen and its presentation can serve as effective immune-therapeutics that can target specific immunological pathways involved in vitiligo. This chapter highlights those immune-regulatory genes involved in vitiligo susceptibility and loci identified to date and their implications in vitiligo pathogenesis.

Age and genotype dependent erythropoietin protection in COVID-19

Erythropoietin (EPO) is the main mediator of erythropoiesis and an important tissue protective hormone that appears to mediate an ancestral neuroprotective innate immune response mechanism at an early age. When the young brain is threatened-prematurity, neonatal hyperbilirubinemia, malaria- EPO is hyper-secreted disproportionately to any concurrent anemic stimuli. Under eons of severe malarial selection pressure, neuroprotective EPO augmenting genetic determinants such as the various hemoglobinopathies, and the angiotensin converting enzyme (ACE) I/D polymorphism, have been positively selected. When malarial and other cerebral threats abate and the young child survives to adulthood, EPO subsides. Sustained high ACE and angiotensin II (Ang II) levels through the ACE D allele in adulthood may then become detrimental as witnessed by epidemiological studies. The ubiquitous renin angiotensin system (RAS) influences the α-klotho/fibroblast growth factor 23 (FGF23) circuitry, and both are interconnected with EPO. Here we propose that at a young age, EPO augmenting genetic determinants through ACE D allele elevated Ang II levels in some or HbE/beta thalassemia in others would increase EPO levels and shield against coronavirus disease 2019, akin to protection from malaria and dengue fever. Human evolution may use ACE2 as a “bait” for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to gain cellular entry in order to trigger an ACE/ACE2 imbalance and stimulate EPO hypersecretion using tissue RAS, uncoupled from hemoglobin levels. In subjects without EPO augmenting genetic determinants at any age, ACE2 binding and internalization upon SARS-CoV-2 entry would trigger an ACE/ACE2 imbalance, and Ang II oversecretion leading to protective EPO stimulation. In children, low nasal ACE2 Levels would beneficially augment this imbalance, especially for those without protective genetic determinants. On the other hand, in predisposed adults with the ACE D allele, ACE/ACE2 imbalance, may lead to uncontrolled RAS overactivity and an Ang II induced proinflammatory state and immune dysregulation, with interleukin 6 (IL-6), plasminogen activator inhibitor, and FGF23 elevations. IL-6 induced EPO suppression, aggravated through co-morbidities such as hypertension, diabetes, obesity, and RAS pharmacological interventions may potentially lead to acute respiratory distress syndrome, cytokine storm and/or autoimmunity. HbE/beta thalassemia carriers would enjoy protection at any age as their EPO stimulation is uncoupled from the RAS system. The timely use of rhEPO, EPO analogs, acetylsalicylic acid, bioactive lipids, or FGF23 antagonists in genetically predisposed individuals may counteract those detrimental effects.

Angiotensin-Converting Enzyme Gene Polymorphism Influences Gastrointestinal Motility in Type 2 Diabetes Mellitus

Uncontrolled diabetes mellitus may affect any part of the gastrointestinal tract (GIT) and impact negatively the quality of life. Angiotensin-converting enzyme (ACE) gene polymorphism can have direct effect on circulating level of ACE which further modifies the degradation of substance P and thus may influence the gut motility. Hence, it could be hypothesised that ACE gene polymorphism would influence the gut motility. An observational analytical study was conducted at PGIMER, Chandigarh. 300 Type2 diabetes mellitus (T2DM) and 200 age and sex matched healthy individuals were enrolled. After taking written consent, 5 ml blood sample was collected for measurement of substance P by ELISA method and for ACE gene polymorphism (insertion[I]/deletion[D]) by polymerase chain reaction. Orocecal transit time (OCTT) was measured using non-invasive lactulose breath test. Out of 300 diabetic patients, 32.7%, 44% and 23.3% belonged to II, ID and DD genotypes, respectively. The frequency of D allele (OR = 1.39) and DD genotype (OR = 2.17) was significantly higher in patients than in controls and was associated with increased risk. Moreover, more number of diabetes patients with constipation (90%) belonged to DD genotype and their OCTT was significantly delayed (166.7 ± 7.3 min) as compared to ID (143.5 ± 4.2 min) or II (121.8 ± 4.9 min) genotype. From this study, it could be concluded that ACE gene polymorphism could be an important contributing factor to influence the gut motility and thus giving rise to the GI symptoms for T2DM patients.

Overlap Syndromes in Sarcoidosis: Clinical Features and Outcomes

Sarcoidosis is a multisystem inflammatory disease characterized by noncaseating granulomatous inflammation. While pulmonary sarcoidosis is most common, extrapulmonary involvement occurs in 50 to 74% of patients and can be the presenting abnormality in some patients. The diagnosis of sarcoidosis is based on a compatible clinical presentation in combination with granulomas on histology and exclusion of other causes. However, the absence of a diagnostic biomarker for sarcoidosis, in addition to the overlap of granulomatous inflammation and nonspecific clinical findings with other diseases, often results in a delayed diagnosis. Sarcoidosis overlap syndromes are typically described when sarcoidosis is diagnosed in the presence of another disease (concurrently or sequentially) with shared clinical and histologic features, or when sarcoidosis presents with clinical features typically observed in, but not diagnostic of, other diseases. Awareness of overlap syndromes is important for clinicians to avoid diagnostic errors and evaluate for concomitant diagnoses that may impact the management and outcome of sarcoidosis. This article is intended to provide an overview of these presentations and the most commonly associated diseases, with attention to their prevalence, clinical features, and reciprocal impacts on disease outcomes.

Biomarkers and Gene Polymorphisms in Members of Long- and Short-lived Families: A Longevity Study

Background

The influence of biomarkers in human lifespan has been investigated but with no clear results yet.

Materials and methods

Lipids, Uric Acid (UA), Adiponectin (ADIPOQ), Insulin-like Growth Factor (IGF-1), cholesteryl ester transfer protein (CETP) and angiotensin-converting enzyme (ACE) proteins, as well as CETP, ADIPOQ, insulin-like growth factor binding protein-3 (IGFBP3) and ACE-gene polymorphisms were evaluated in 149 Greek individuals. The Long-Lived Families (LON) (n=84) comprised of 3 generations: long-lived aged ≥90 years (P), offspring (FL1) and their grandchildren (FL2), while the Short-Lived Families (EAD) (n=65) where both parents died <75 years, comprised of 2 generations: middle-aged (FD1) and children (FD2).

Results

Serum CETP and IGF-1 levels were lower, whereas AdipoQ concentrations were higher in P compared with FL1 and FL2 members (CETP: p = 0.03 for both comparisons; IGF-1 p < 0.001 for both comparisons and ADIPOQ: p = 0.001 and p = 0.004, respectively). Furthermore, serum triglycerides, UA and glucose concentrations were higher in FD1 compared with FD2 subjects (p=0.001, 0.02 and ≤0.001, respectively). In FD2 and FL2, CETP levels were lower in individuals with B2B2 compared with B1B1 genotype (p=0.007). Additionally, ACE concentrations were higher in individuals with DD compared with II genotype in both Families (p=0.001). After adjustment for age and gender, CETP levels were lower in P and FL2 individuals with B2B2 compared with the B1B1 genotype (p=0.004 and 0.007, respectively).

Conclusion

Increase serum TGs, UA and GL concentrations were higher in the middle-aged individuals compared with their children in families independently of their lifespan. The serum adiponectin concentration was the highest in the oldest old individuals implying beneficial influence on lifespan. Independently of family's lifespan history, the youngest individuals with CETPB2B2 genotype, compared with individuals with CETPB1B1 genotypes, had lower serum CETP concentrations. The knowledge of the unfavourable gene(s)influencing human lifespan may be helpful in encouraging individuals to follow healthier lifestyle habits and better control their high-risk biomarkers.

Association of Angiotensin-Converting Enzyme (ACE) Gene Polymorphism with Inflammation and Cellular Cytotoxicity in Vitiligo Patients

BACKGROUND

Vitiligo is a disorder with profound heterogeneity in its aetio-pathophysiology. Angiotensin converting enzyme (ACE) plays an important role in the physiology of the vasculature, blood pressure and inflammation. An insertion/deletion (I/D) polymorphism of the ACE gene was reported be associated with the development of vitiligo.

OBJECTIVE

Our aim was to evaluate the ACE I/D polymorphism in vitiligo patients and controls. Our second aim was to find a possible association between ACE gene polymorphism and inflammatory mediators (as interleukin (IL)-6) and/or cellular cytotoxicity induced by serum nitrite (as a breakdown product of the cytotoxic nitric oxide) in vitiligo patients.

METHODS

This case-control study included 74 vitiligo patients and 75 apparently healthy controls. The distribution of ACE gene I/D genotype was investigated using PCR. Serum ACE, IL-6 and nitrite were measured by colorimetric method, ELISA and Griess assay respectively.

RESULTS

The ACE allele frequency was significantly different between vitiligo patients and healthy controls (P = 0.026). However there was no significant difference between the ACE genotyping frequency in both groups (P = 0.115). There were statistically significant higher VIDA score (P = 0.007), and serum IL-6 (P < 0.001) in patients with the DD genotype when compared to other genotypes. Serum nitrite in patients with the DD genotype was significantly higher (P = 0.007) when compared to patients with II genotype. Serum levels of ACE, IL-6 and nitrite in vitiligo patients were statistically significantly higher than those in controls.

CONCLUSION

As a conclusion, ACE gene polymorphism might grant susceptibility to develop vitiligo. Serum IL-6 and nitrite levels might have an important role in the pathogenesis of vitiligo. Targeting these two factors might have an implication in the treatment of some resistant cases.

Association between I/D polymorphism in the ACE gene and sarcoidosis in Turkish patients

Sarcoidosis is a chronic inflammatory disease with a complex pathogenesis and unknown etiology characterized by noncaseating granulomas that invade the lungs, eyes, liver and other organs. Insertion (I)/deletion (D) polymorphism in the gene encoding the angiotensin-converting enzyme (ACE) has been studied to examine the genetic predisposition to sarcoidosis in different populations, but the results have been inconsistent and inconclusive. This study aimed to determine the frequencies of the genotypes and alleles of I/D polymorphism in the ACE gene in Turkish patients as a distinct ethnic group and to investigate whether such polymorphism is associated with predisposition to sarcoidosis. Genomic DNA samples obtained from 154 individuals (70 patients with sarcoidosis and 84 healthy controls) were used in the study. The DNA was amplified using polymerase chain reactions using allele-specific primers. The amplified products were analyzed by 2 % agarose gel electrophoresis followed by UV transillumination. The allele frequencies and genotype distribution of the groups were analyzed using the Chi square test. There were no significant differences between the controls and sarcoidosis cases with respect to genotype distribution (χ(2) = 4.202, p = 0.122) and allele frequencies (χ(2) = 1.358, p = 0.244). Our results suggest that I/D polymorphism in the ACE gene does not cause a genetic predisposition to sarcoidosis in Turkish patients.

The angiotensin-converting enzyme gene insertion/deletion polymorphism in Indian patients with vitiligo: a case-control study and meta-analysis

BACKGROUND

Vitiligo is a common, acquired, idiopathic depigmenting skin disorder. Although the exact pathogenesis remains unknown, genetic susceptibility and autoimmune responses play a role in vitiligo development. Previous studies have suggested that the D allele of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with vitiligo in Indians and Koreans. Furthermore, significantly higher serum ACE levels have been demonstrated in patients with some autoimmune and autoinflammatory disorders.

OBJECTIVES

The objectives were to investigate any association between the ACE I/D polymorphism and vitiligo susceptibility in an Indian population, and to compare serum ACE levels in patients with vitiligo and healthy subjects.

METHODS

The ACE I/D genotypes of 79 patients with vitiligo and 100 normal individuals were determined by polymerase chain reaction amplification. A meta-analysis was done to compare the distribution of the ACE I/D alleles and genotypes in the current and three previous studies. Serum ACE levels were evaluated by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in the frequency of the ACE I/D D allele was evident in patients with vitiligo in both the case-control study [P=0·005; odds ratio (OR) 1·87; 95% confidence intervals (CI) 1·22-2·85] and the meta-analysis (P=0·044; OR 1·44; 95% CI 1·01-2·06). Serum ACE levels were significantly increased in patients with vitiligo compared with healthy subjects (P<0·0001).

CONCLUSIONS

In agreement with earlier reports, the ACE I/D D allele is associated with vitiligo susceptibility in the Indian population. The significantly elevated serum ACE levels in our cohort of patients with vitiligo concur with those previously found in patients with some other autoimmune diseases.

Angiotensin-converting enzyme deletion allele is beneficial for the longevity of Europeans

The human angiotensin converting enzyme (ACE) gene is one of the most investigated candidate genes for cardiovascular diseases (CVD), but the understanding of its role among the elderly is vague. Therefore, this study focuses at: (a) testing the association of ACE polymorphism with CVD risk factors among the elderly, and (b) detecting the possible unequal distribution of ACE genotypes between senescent and younger segments of the European populations. The association of ACE I/D polymorphism with CVD health status [hypertension (HT), obesity, dislypidemia] in 301 very old subjects (88.2 ± 5 years; F/M = 221/80) was tested by means of logistic regression analysis. The meta-analysis of D allele frequency in general vs. elderly (80+ years) groups was conducted using all publicly available data for European populations comprising both age cohorts. Multiple multinomial logistic regression revealed that within this elderly sample, age (younger olds, 80-90 years), female sex (OR = 3.13, 95% CI = 1.59-6.19), and elevated triglycerides (OR = 2.53, 95% CI = 1.29-4.95) were positively associated with HT, while ACE polymorphism was not. It was also established that the DD genotype was twice as high in 80+ cohort compared to general population of Croatia (p < 0.00001). This trend was confirmed by the meta-analysis that showed higher D allele frequencies in olds from nine of ten considered European populations (OR = 1.19, 95% CI = 1.08-1.31). The data in elderly cohort do not confirm previously reported role of ACE DD genotype to the development of HT. Moreover, meta-analysis indicated that ACE D allele has some selective advantage that contributes to longevity in majority of European populations.

Association of angiotensin converting enzyme gene insertion/deletion polymorphism with lung cancer in Turkey

Angiotensin-converting enzyme (ACE) plays an important role in the physiological control of blood pressure and inflammation. We investigated an insertion/deletion (I/D) polymorphism of the gene for ACE in relation to cardiovascular, cerebrovascular, neurodegenerative, and inflammatory diseases. The purpose of the present study was to investigate a possible association between lung cancer and insertion/deletion polymorphism of the ACE gene. A total of 125 patients with lung cancer and 165 control subjects were enrolled in the present study. ACE I/D genotypes were determined by polymerase chain reaction. Allelic frequencies and genotype distribution of the ACE I/D polymorphism in the patient group were significantly different from control subjects (ACE II genotype 29.6 vs. 17.6%, P = 0.011; ACE I allele 49.6 vs. 39.4%, P =0.009). Our data suggest that the ACE I/D polymorphism could be a risk factor for patients with lung cancer.

Association between ACE gene I/D polymorphism and clinical presentation and prognosis of sarcoidosis

Serum angiotensin converting enzyme (SACE) concentration is considered a marker of sarcoidosis activity. This concentration is influenced by an insertion/deletion (I/D) polymorphism of the ACE gene, such that SACE levels follow the pattern DD>ID>II. The aim of our work was to study the relationship between I/D polymorphism and susceptibility to sarcoidosis, as well as the relation between this polymorphism and the clinical presentation and evolution of the disease in 177 sarcoidosis patients. A group of 104 individuals without sarcoidosis was included as control. Genotyping was done by a polymerase chain reaction (PCR) method, and SACE concentration at diagnosis was determined by a kinetic method. No differences were observed in genotype or allele distributions between patients and controls, nor between patients considering the type of presentation (Löfgren versus non-Löfgren) and evolution of the disease (acute versus chronic). As reported for healthy populations, SACE concentrations followed the pattern DD>ID>II in sarcoidosis patients, but significant differences between genotypes existed only in the Löfgren group (p = 0.003) and in acute patients (p = 0.02). SACE concentrations at diagnosis were lower in acute patients (p = 0.05) and in Löfgren's syndrome (p = 0.04), but this seemed to occur only in ID individuals (p = 0.02 and p = 0.01, respectively). No relation was thus found between I/D polymorphism and susceptibility to sarcoidosis, but ACE I/D genotyping may improve the assessment of disease activity, both at diagnosis and during the follow-up of treated and untreated patients.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in inflammatory bowel diseases

INTRODUCTION

The renin-angiotensin system is strictly related to the kallikrein-kinin system and both are involved in many physiological and disease conditions and possibly in the pathogenesis of inflammatory bowel disease (IBD). Angiotensin-converting enzyme (ACE) is the pivotal enzyme of the renin-angiotensin system and the main catabolic enzyme of the kallikrein-kinin system. The ACE I/D (insertion/deletion) is a polymorphism of the gene encoding for ACE: participants who are homozygous for the D allele exhibit higher ACE levels, which in turn appear to play a deleterious role in several diseases.

AIM

To study the prevalence of ACE I/D polymorphism in IBD patients and its possible association with disease features.

METHODS

A total of 232 IBD patients, 124 with ulcerative colitis (UC) and 108 with Crohn's disease and 99 healthy controls were genotyped for the ACE I/D polymorphism.

RESULTS

DD, ID and II genotypes distribution did not show significant differences between IBD patients and controls: 42.2 vs. 40.4%, 42.7 vs. 47.5% and 15.1 vs. 12.1%, respectively. No significant difference was observed between Crohn's disease and UC patients. Within UC patients, the presence of DD genotype and the carriage of the D allele were significantly associated with the presence of extraintestinal manifestations: odds ratio (OR) 4.08, 95% confidence interval (CI): 1.62-10.28; P<0.003 and OR=3.07, 95% CI: 1.45-6.48; P<0.003, respectively. No significant association was found with other IBD clinical features.

CONCLUSIONS

The ACE I/D polymorphism is not associated with IBDs but the D allele appears to increase the risk of developing extraintestinal manifestations in UC patients.

Role of genetic polymorphisms in ACE and TNF-alpha gene in sarcoidosis: a meta-analysis

A great number of association studies have been performed to identify the genes involved in the etiology and prognosis of sarcoidosis. We performed a systematic review of case-control studies through the PubMed database and evaluated them for a possible inclusion into a meta-analysis in order to assess whether the reported genetic polymorphisms are the risk factors of sarcoidosis. Case-control studies with clear diagnostic criteria and interventions were included. Only investigations of a single polymorphism/gene involvement in sarcoidosis reported more than five times were selected. Aggregating data from 12 studies on ID/ACE polymorphisms, the odds ratio (OR) for sarcoidosis, if the polymorphism was considered under the dominant genetic model, was not significantly increased: 1.19 (95% CI 0.98-1.43); OR under the recessive model was 1.20 (95% CI 0.98-1.46). In seven case-control studies on -308/TNF-alpha polymorphism, the OR for sarcoidosis if the polymorphism considered under the dominant genetic model was significantly increased at 1.47 (95% CI 1.03-2.08); the OR under the recessive model was 1.39 (95% CI 0.67-2.90). In conclusion, the results showed that the TNF-alpha genotype could be a significant risk factor for sarcoidosis, whereas the risk of sarcoidosis due to the ACE genotype was not substantially elevated.

Angiotensin-converting enzyme gene insertion/deletion polymorphism is associated with risk of oral precancerous lesion in betel quid chewers

To investigate whether angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism is related to the risk of oral precancerous lesions (OPL) in Taiwanese subjects who chew betel quid, a total of 61 betel quid chewers having OPL were compared with 61 asymptomatic betel quid chewers matched for betel quid chewing duration and dosage. The frequency of homozygote for ACE D variant is significantly higher in the case subjects than that of the controls (44.3 vs 24.6%; P=0.0108). The adjusted odds ratio of the D homozygous for the risk of OPL is 8.10 (95% confidence interval (CI)=2.04–32.19, P=0.003). In the allelic base analysis, the D allele is also significantly associated with higher risk of OPL. When grouping the study subjects by smoking status, the association between ACE I/D polymorphism and risk of OPL was only observed in nonsmokers. Our results support the theory that genetic factors may contribute to the susceptibility of OPL and suggest that smoking and genetic factors may be differently involved in the development of OPL.

An insertion/deletion polymorphism in the gene encoding angiotensin converting enzyme is not associated with generalised vitiligo in an English population

Vitiligo is an acquired hypomelanotic skin disorder characterised by circumscribed depigmented macules resulting from the loss of functional melanocytes from the cutaneous epidermis and autoimmunity has been suggested to play a role in the pathogenesis of the disease. Recently, an insertion/deletion (I/D) polymorphism of a 287-base pair repetitive sequence in intron 16 of the angiotensin converting enzyme (ACE) gene has been associated with autoimmune disease and with the development of vitiligo. In this study, the distribution of ACE gene I/D genotypes was investigated in a population of 106 English patients with generalised (non-segmental) vitiligo and 174 ethnically matched healthy controls using a restriction fragment length polymorphism-polymerase chain reaction genotyping method. No significant difference in the frequencies of II, ID and DD genotypes was detected between vitiligo patients and control subjects (P=0.35). The same result was evident for the genotype distribution in vitiligo patients with an autoimmune disease and for those without when compared with controls (P=0.33 and P=0.53, respectively). In addition, the results indicated that the D allele was not significantly over-represented in the group of patients with vitiligo compared with controls (P=0.42) and that this was also the case for patients with and without associated autoimmunity (P=0.40 and P=0.62, respectively).

The genetic concept of vitiligo

Vitiligo is a relatively common, acquired pigmentary disorder characterized by areas of depigmented skin resulting from loss of epidermal melanocytes. The prevalence of this disease varies from 0.1 to 2% in various global populations. The genetics of vitiligo cannot be explained by simple Mendelian genetics; it is characterized by incomplete penetrance, multiple susceptibility loci and genetic heterogeneity. Unraveling the complex genetics of vitiligo is a daunting challenge but the perseverance of vitiligo gene hunters has produced commendable results in recent years. Although environmental factors are important, there is considerable evidence that genes also play a significant role in its pathogenesis. Strong evidence from twin and family studies indicates the importance of genetic factors in the development of vitiligo, although it is clear that these influences are complex. Linkage and association studies have also provided strong support for vitiligo susceptibility genes on chromosomes 4q13-q21, 1p31, 7q22, 8p12 and 17p13, while loci of interest at 6p, 6q, 14q, 9q, 13q, 19p and 22q require further follow-up. Although important obstacles to further progress will need to be overcome, the successes of the past 5 years suggest that a detailed description of the genetic basis of vitiligo is a realistic goal. In the future, dissection of the complex genetic architecture of vitiligo will provide new approaches for treatment and prevention. In this article, we will give an overview of the latest findings in the genetics of vitiligo.

Serum biomarkers in interstitial lung diseases

The use of biomarkers in medicine lies in their ability to detect disease and support diagnostic and therapeutic decisions. New research and novel understanding of the molecular basis of the disease reveals an abundance of exciting new biomarkers who present a promise for use in the everyday clinical practice. The past fifteen years have seen the emergence of numerous clinical applications of several new molecules as biologic markers in the research field relevant to interstitial lung diseases (translational research). The scope of this review is to summarize the current state of knowledge about serum biomarkers in interstitial lung diseases and their potential value as prognostic and diagnostic tools and present some of the future perspectives and challenges.

Association of angiotensin converting enzyme gene I/D polymorphism of vitiligo in Korean population

Vitiligo (leukoderma) is an acquired idiopathic hypomelanotic disorder characterized by the circumscribed depigmented patches. Vitiligo is a polygenic disease. The exact pathogenesis is not yet known. The angiotensin converting enzyme (ACE) gene was selected as a candidate gene as ACE plays an important role in the physiology of the vasculature, blood pressure and inflammation, and its relationship with various diseases, including autoimmune diseases, has been widely investigated. The I/D polymorphism of ACE gene in vitiligo patients has not been reported. In this study, we investigated ACE gene polymorphism in 120 vitiligo patients and in 429 healthy volunteers in Korea. The ACE gene genotype distribution (P = 0.032) and allele frequency (P = 0.012) were significantly different between vitiligo patients and healthy controls. This study suggests that the ACE gene polymorphism has a strong association with the development of vitiligo in Korean patients.

Angiotensin-converting enzyme gene polymorphisms in patients with pulmonary sarcoidosis: impact on disease severity

Angiotensin converting enzyme (ACE) is a metallopeptidase with a key function in the regulation of blood pressure and volume. The ACE1 gene, on chromosome 17, contains a insertion/deletion (I/D) polymorphism in intron 16. The D allele of this polymorphism is linked with raised serum ACE (sACE) levels. Sarcoidosis is a systemic disease of granulomatous inflammation that primarily affects the lung and lymph system. It is often accompanied by elevated sACE related to ACE production from granuloma cells. The ACE I/D polymorphism has been tested for association or linkage with the risk of sarcoidosis. Though published results are conflicting, there seems to be suggestive evidence of a minor pro-inflammatory influence of the ACE D allele in sarcoidosis. At present, a more accurate interpretation of sACE levels in diagnosis and monitoring of sarcoidosis seems to be the main value of ACE I/D genotyping.

Sarcoidosis and other autoimmune disorders

The relation between sarcoidosis and autoimmune disorders was first suggested by Telium about half a century ago. He noted that there were certain clinical and laboratory similarities between systemic lupus erythematosus and sarcoidosis and mused that the common features were hyperglobulinemia, "hyalinosis" in the reticuloendothelial system, epithelioid cell granulomas, and periarterial hyaline zones in the spleen. Now, the inclusion of sarcoidosis into the group of disorders of autoimmunity is a discarded notion. Sarcoidosis does not meet the criteria for autoimmune disease. Nevertheless, there are ample examples of coexistence of sarcoidosis and a wider range of autoimmune disorders.

Angiotensin-converting enzyme gene polymorphism in relation to HLA-DR in sarcoidosis

OBJECTIVES

To investigate if an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene associates with HLA-DR alleles previously found to be of prognostic interest in Scandinavian sarcoidosis patients. This may contribute to characteristics associated with these HLA-DR alleles, such as a good (DR17) or poor (DR14 or 15) prognosis. DESIGN, SETTINGS AND SUBJECTS: Polymerase chain reaction (PCR) was used for analysing an I/D polymorphism in the gene coding for ACE in 138 subjects; 65 controls and 73 sarcoidosis patients, and for HLA-DR genotyping 67 patients. Serum ACE level (S-ACE) was measured in all controls and 72 patients. Sixty-one patients were classified as chronic or nonchronic after 2 years follow-up. All patients were recruited and followed at our outpatient clinic.

RESULTS

No significant differences in ACE alleles or genotypes were seen between controls and patients or between patients positive and negative for DR17 or DR14/15. The ACE genotype did not differ between nonchronic and chronic patients. The ACE genotype tended to influence the S-ACE in patients, whilst in controls S-ACE significantly differed between the ACE genotypes.

CONCLUSION

This study does not support an association between ACE genotype and sarcoidosis or disease outcome. However, because significantly (P < 0.001) more DR17 positive (17 of 19) than DR14/15 positive (seven of 26) patients were classified as nonchronic, these results instead strengthen the prognostic importance of HLA-DR alleles in Scandinavian sarcoidosis patients.

Genotyping in the MHC locus: potential for defining predictive markers in sarcoidosis

In sarcoidosis, host genetic factors are discussed as contributing to disease susceptibility and course. Since tumor necrosis factor (TNF)-alpha is a central mediator of granuloma formation and since elevated TNF-alpha levels are found during active phases of sarcoidosis, genetic polymorphisms correlating with influences on TNF-alpha levels are of special interest. The complete sequencing of the MHC region and the increase in the number of identified gene polymorphisms in this locus associated with TNF-alpha production offer the opportunity of detecting new genes associated with sarcoidosis and perhaps of defining disease-associated haplotypes that bear the potential of serving as predictive markers for this disease.

Surfactant gene polymorphisms and interstitial lung diseases

Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs). Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

Ace gene I/D polymorphism and sarcoidosis pulmonary disease severity

Previous studies of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene in sarcoidosis have revealed both ethnic heterogeneity of I/D frequencies and controversy surrounding the association between the polymorphism and severity of disease. The objective of this study was, therefore, to clarify the role of the ACE I/D polymorphism in (1) disease susceptibility, (2) pulmonary disease severity (with particular reference to pulmonary fibrosis), and (3) pulmonary disease progression, in two distinct European sarcoidosis populations. Standard chest radiographic staging was performed on 118 UK and 56 Czech white patients with sarcoidosis at 2 yr from presentation. Pulmonary function data were analyzed, and patients were then categorized according to disease severity. A PCR-SSP assay was used to determine the ACE I/D genotype of each patient studied. The I/D allele frequencies from these patients were compared with frequencies from ethnically matched UK (n = 386) and Czech (n = 179) control subjects using a chi-square contingency table. No significant differences were seen in the distribution of the ACE I/D genotypes, allele frequencies or phenotype frequencies. Furthermore, no association was found between the ACE I/D polymorphism and pulmonary disease severity, fibrosis, and progression. We conclude that the ACE I/D polymorphism has no role in sarcoidosis susceptibility in European whites and that it is not a regulatory variant in this disease.

Angiotensin-converting enzyme (ACE) gene polymorphisms and familial occurrence of sarcoidosis

OBJECTIVES

The aim of this study was to test for genetic linkage and association between polymorphisms of the angiotensin-converting enzyme (ACE) gene and familial occurrence of sarcoidosis.

DESIGN, SETTING AND SUBJECTS

German families with more than one member suffering from sarcoidosis were contacted and a DNA bank was established. Sixty-two families (140 patients, 77 females and 63 males, and 104 unaffected relatives) were genotyped for the ACE gene insertion/deletion (I/D) polymorphism and for two flanking variable sites (ACE A-5466C and ACE 4656(CT)2/3). As controls, 100 DNAs from unrelated resident Caucasians (50 females, 50 males) were analysed. ACE allele and genotype frequencies were determined, and parametric linkage and affected sib pair analyses and transmission disequilibrium tests were performed.

RESULTS

There was a striking over-representation of the ACE I/D genotype DD in patients with sarcoidosis and their families as compared with controls of the study and well founded genotype frequencies from the literature. The same was evident for the accompanying genotypes CC and 2,2 of the flanking polymorphisms. Linkage between the segregation of ACE alleles and the disorder within families was clearly excluded for simple models of inheritance. However, there was a suggestive but not significant (P = 0.06) excess of allele sharing amongst affected siblings. There was no transmission disequilibrium for any ACE allele or haplotype.

CONCLUSIONS

ACE is involved in the pathogenesis of sarcoidosis, but the ACE polymorphisms are not an inherited main cause of the disease. They are more likely to modify the development of the disorder, and the ACE I/D genotype DD might be a promoter to clinical manifestation.