Evaluation of the influence of genetic variants in Cereblon gene on the response to the treatment of erythema nodosum leprosum with thalidomide.

BACKGROUND: Erythema nodosum leprosum (ENL) is an acute and systemic inflammatory reaction of leprosy characterised by painful nodules and involvement of various organs. Thalidomide is an immunomodulatory and anti-inflammatory drug currently used to treat this condition. Cereblon (CRBN) protein is the primary target of thalidomide, and it has been pointed out as necessary for the efficacy of this drug in others therapeutics settings. OBJECTIVES: In this study, we aimed to evaluate the influence of CRBN gene variants on the dose of thalidomide as well as its adverse effects during treatment of ENL. METHODS: A total of 103 ENL patients in treatment with thalidomide were included in this study. DNA samples were obtained from saliva and molecular analysis of CRBN gene were performed to investigate the variants rs1620675, rs1672770 and rs4183. Different genotypes of CRBN variants were evaluated in relation to their influence on the dose of thalidomide and on the occurrence of adverse effects. FINDINGS: No association was found between CRBN variants and thalidomide dose variation. However, the genotypes of rs1672770 showed association with gastrointestinal effects (p = 0.040). Moreover, the haplotype DEL/C/T (rs4183/rs1672770/rs1620675) was also associated with gastrointestinal adverse effects (p = 0.015). MAIN CONCLUSIONS: Our results show that CRBN variants affect the treatment of ENH with thalidomide, especially on the adverse effects related to the drug.

The cellular architecture of the antimicrobial response network in human leprosy granulomas.

Granulomas are complex cellular structures composed predominantly of macrophages and lymphocytes that function to contain and kill invading pathogens. Here, we investigated the single-cell phenotypes associated with antimicrobial responses in human leprosy granulomas by applying single-cell and spatial sequencing to leprosy biopsy specimens. We focused on reversal reactions (RRs), a dynamic process whereby some patients with disseminated lepromatous leprosy (L-lep) transition toward self-limiting tuberculoid leprosy (T-lep), mounting effective antimicrobial responses. We identified a set of genes encoding proteins involved in antimicrobial responses that are differentially expressed in RR versus L-lep lesions and regulated by interferon-γ and interleukin-1ß. By integrating the spatial coordinates of the key cell types and antimicrobial gene expression in RR and T-lep lesions, we constructed a map revealing the organized architecture of granulomas depicting compositional and functional layers by which macrophages, T cells, keratinocytes and fibroblasts can each contribute to the antimicrobial response.

Large-Scale Gene Expression Signatures Reveal a Microbicidal Pattern of Activation in Mycobacterium leprae-Infected Monocyte-Derived Macrophages With Low Multiplicity of Infection.

Leprosy is a disease with a clinical spectrum of presentations that is also manifested in diverse histological features. At one pole, lepromatous lesions (L-pole) have phagocytic foamy macrophages heavily parasitized with freely multiplying intracellular Mycobacterium leprae. At the other pole, the presence of epithelioid giant cells and granulomatous formation in tuberculoid lesions (T-pole) lead to the control of M. leprae replication and the containment of its spread. The mechanism that triggers this polarization is unknown, but macrophages are central in this process. Over the past few years, leprosy has been studied using large scale techniques to shed light on the basic pathways that, upon infection, rewire the host cellular metabolism and gene expression. M. leprae is particularly peculiar as it invades Schwann cells in the nerves, reprogramming their gene expression leading to a stem-like cell phenotype. This modulatory behavior exerted by M. leprae is also observed in skin macrophages. Here, we used live M. leprae to infect (10:1 multiplicity of infection) monocyte-derived macrophages (MDMs) for 48 h and analyzed the whole gene expression profile using microarrays. In this model, we observe an intense upregulation of genes consistent with a cellular immune response, with enriched pathways including peptide and protein secretion, leukocyte activation, inflammation, and cellular divalent inorganic cation homeostasis. Among the most differentially expressed genes (DEGs) are CCL5/RANTES and CYP27B1, and several members of the metallothionein and metalloproteinase families. This is consistent with a proinflammatory state that would resemble macrophage rewiring toward granulomatous formation observed at the T-pole. Furthermore, a comparison with a dataset retrieved from the Gene Expression Omnibus of M. leprae-infected Schwann cells (MOI 100:1) showed that the patterns among the DEGs are highly distinct, as the Schwann cells under these conditions had a scavenging and phagocytic gene profile similar to M2-like macrophages, with enriched pathways rearrangements in the cytoskeleton, lipid and cholesterol metabolism and upregulated genes including MVK, MSMO1, and LACC1/FAMIN. In summary, macrophages may have a central role in defining the paradigmatic cellular (T-pole) vs. humoral (L-pole) responses and it is likely that the multiplicity of infection and genetic polymorphisms in key genes are gearing this polarization.

Large-scale gene expression signatures reveal a microbicidal pattern of activation in Mycobacterium leprae-infected monocyte-derived macrophages with low multiplicity of infection

Leprosy is a disease with a clinical spectrum of presentations that is also manifested in diverse histological features. At one pole, lepromatous lesions (L-pole) have phagocytic foamy macrophages heavily parasitized with freely multiplying intracellular Mycobacterium leprae. At the other pole, the presence of epithelioid giant cells and granulomatous formation in tuberculoid lesions (T-pole) lead to the control of M. leprae replication and the containment of its spread. The mechanism that triggers this polarization is unknown, but macrophages are central in this process. Over the past few years, leprosy has been studied using large scale techniques to shed light on the basic pathways that, upon infection, rewire the host cellular metabolism and gene expression. M. leprae is particularly peculiar as it invades Schwann cells in the nerves, reprogramming their gene expression leading to a stem-like cell phenotype. This modulatory behavior exerted by M. leprae is also observed in skin macrophages. Here, we used live M. leprae to infect (10:1 multiplicity of infection) monocyte-derived macrophages (MDMs) for 48 h and analyzed the whole gene expression profile using microarrays. In this model, we observe an intense upregulation of genes consistent with a cellular immune response, with enriched pathways including peptide and protein secretion, leukocyte activation, inflammation, and cellular divalent inorganic cation homeostasis. Among the most differentially expressed genes (DEGs) are CCL5/RANTES and CYP27B1, and several members of the metallothionein and metalloproteinase families. This is consistent with a proinflammatory state that would resemble macrophage rewiring toward granulomatous formation observed at the T-pole. Furthermore, a comparison with a dataset retrieved from the Gene Expression Omnibus of M. leprae-infected Schwann cells (MOI 100:1) showed that the patterns among the DEGs are highly distinct, as the Schwann cells under these conditions had a scavenging and phagocytic gene profile similar to M2-like macrophages, with enriched pathways rearrangements in the cytoskeleton, lipid and cholesterol metabolism and upregulated genes including MVK, MSMO1, and LACC1/FAMIN. In summary, macrophages may have a central role in defining the paradigmatic cellular (T-pole) vs. humoral (L-pole) responses and it is likely that the multiplicity of infection and genetic polymorphisms in key genes are gearing this polarization.

Involvement of TNF-Producing CD8+ Effector Memory T Cells with Immunopathogenesis of Erythema Nodosum Leprosum in Leprosy Patients.

Type 2 reaction (T2R) or erythema nodosum leprosum (ENL), a sudden episode of acute inflammation predominantly affecting lepromatous leprosy patients (LL), characterized by a reduced cellular immune response. This possibly indicates a close relationship between the onset of T2R and the altered frequency, and functional activity of T lymphocytes, particularly of memory subsets. This study performed ex vivo and in vitro characterizations of T cell blood subpopulations from LL patients with or without T2R. In addition, the evaluation of activity of these subpopulations was performed by analyzing the frequency of these cells producing IFN-γ, TNF, and IL-10 by flow cytometry. Furthermore, the expression of transcription factors, for the differentiation of T cells, were analyzed by quantitative real-time polymerase chain reaction. Our results showed an increased frequency of CD8+/TNF+ effector memory T cells (TEM) among T2Rs. Moreover, there was evidence of a reduced frequency of CD4 and CD8+ IFN-γ-producing cells in T2R, and a reduced expression of STAT4 and TBX21. Finally, a significant and positive correlation between bacteriological index (BI) of T2R patients and CD4+/TNF+ and CD4+/IFN-γ+ T cells was observed. Thus, negative correlation between BI and the frequency of CD4+/IL-10+ T cells was noted. These results suggest that CD8+/TNF+ TEM are primarily responsible for the transient alteration in the immune response to Mycobacterium leprae in ENL patients. Thus, our study improves our understanding of pathogenic mechanisms and might suggest new therapeutic approaches for leprosy.

Complement C1q expression in Erythema nodosum leprosum.

Complement C1q is a soluble protein capable of initiating components of the classical pathway in host defence system. In earlier qualitative studies, C1q has been implicated in the pathogenesis of Erythema Nodosum Leprosum (ENL). However, little is known about the role of this complement in ENL reaction. In the present study we described the protein level of C1q production and its gene expression in the peripheral blood and skin biopsies in patients with ENL reaction and lepromatous leprosy (LL) patient controls before and after treatment. Thirty untreated patients with ENL reaction and 30 non-reactional LL patient controls were recruited at ALERT Hospital, Ethiopia. Peripheral blood and skin biopsies were obtained from each patient before and after treatment. The level of circulating C1q in the plasma was determined by enzyme-linked immunosorbent assay. The mRNA expression of the three C1q components, C1qA, C1qB, and C1qC in the peripheral blood and skin biopsies was determined by qPCR. Circulating C1q in the peripheral blood of untreated ENL patients was significantly decreased compared to LL patient controls. Untreated ENL patients had increased C1q gene expression in the peripheral blood compared to LL controls. Similarly, C1qA and C1qC gene expression were substantially increased in the skin biopsies of untreated ENL patients compared to LL controls. However, after treatment none of these genes show significant difference in both groups. In conclusion, while circulating C1q is inversely correlated with active ENL reactions, its gene expression is directly correlated with ENL. The decreased circulating C1q may suggest the utilization of C1q in immune-complex formation in these patients. Therefore, C1q could be a potential diagnostic marker for active ENL reactions as well as for monitoring ENL treatment.

Asociación de los polimorfismos T352C y A16974C con la lepra lepromatosa en pacientes cubanos / Association of T352C and A16974C polymorphisms with lepromatose leprosy in cuban patients

Introducción: La Lepra es una enfermedad infecciosa causada por el Mycobacterium leprae. Los patrones dermatoglíficos de pacientes cubanos con lepra lepromatosa mostraron indicios probatorios de que existe predisposición genética para el desarrollo de esta enfermedad, que sugiere la búsqueda de la asociación con polimorfismos moleculares, de mayor precisión. Entre estos, unos de los más estudiados son el T352C del gen del receptor de la vitamina D y el A16974C del gen IL12p40, cuya utilidad relativa depende de la población. Objetivo: Determinar si existe asociación entre la presencia de los polimorfismos T352C y A16974C con la lepra lepromatosa en pacientes cubanos. Material y Métodos: Se realizó un estudio observacional, analítico, de tipo caso-control de asociación genética donde se estudiaron pacientes con lepra lepromatosa y controles. Fueron identificados los genotipos relacionados con los polimorfismos T352C y A16974C en cada grupo. La prueba Chi-cuadrado de Pearson fue utilizada para determinar si los controles se hallaban en equilibrio de Hardy Weinberg, así como si existía relación entre los polimorfismos y la presencia de la enfermedad. Resultados: Los pacientes estudiados fueron 32 para el polimorfismo T352C y 44 para el A16974C. Los controles fueron 64 y 44, respectivamente; estos se hallaron en equilibrio Hardy-Weinberg. No se detectó asociaciónentre los polimorfismos A16974C y T352C con la lepra lepromatosa. Conclusiones: Los polimorfismos T352C y A16974C no son útiles como factor de riesgo predisponente en el grupo de pacientes cubanos con lepra lepromatosa estudiados(AU)

Introduction: Leprosy is an infectious disease caused by Mycobacterium leprae. Dermatoglyphic patterns of Cuban patients with lepromatose leprosy showed evidential signs of the existence of genetic predisposition to the development of this disease, which suggests a search for the association with molecular polymorphisms of higher degree of accuracy. Among them, some of the most studied are the T352C vitamin D receptor gene and the A16974Cof the IL12p40 gene, which relative usefulness depends on the population. Objective: To determine whether there is an association between the T352Cand A16974C polymorphisms with lepromatose leprosy in Cuban patients. Material and methods: An observational analytical case-control type genetic association study was conducted where patients with lepromatose leprosy and controls were studied. Genotypes related to T352Cand A16974C polymorphisms were identified in each group. Pearson´s chi square test was used to determine whether the controls were in Hardy-Weinberg equilibrium, and also whether there was a relation between polymorphisms and the presence of diseases. Results: There were 32 patients under study for T352C polymorphism, and 42 for A16974C. The controls were 64 and 44, respectively; and these were in Hardy-Weinberg equilibrium. No association between T352Cand A16974C polymorphisms with lepromatose leprosy was detected. Conclusions: T352Cand A16974C polymorphisms are not useful as a predisposing risk factor in the group of Cuban patients with lepromatose leprosy studied(AU)

Cell-type deconvolution with immune pathways identifies gene networks of host defense and immunopathology in leprosy.

Transcriptome profiles derived from the site of human disease have led to the identification of genes that contribute to pathogenesis, yet the complex mixture of cell types in these lesions has been an obstacle for defining specific mechanisms. Leprosy provides an outstanding model to study host defense and pathogenesis in a human infectious disease, given its clinical spectrum, which interrelates with the host immunologic and pathologic responses. Here, we investigated gene expression profiles derived from skin lesions for each clinical subtype of leprosy, analyzing gene coexpression modules by cell-type deconvolution. In lesions from tuberculoid leprosy patients, those with the self-limited form of the disease, dendritic cells were linked with MMP12 as part of a tissue remodeling network that contributes to granuloma formation. In lesions from lepromatous leprosy patients, those with disseminated disease, macrophages were linked with a gene network that programs phagocytosis. In erythema nodosum leprosum, neutrophil and endothelial cell gene networks were identified as part of the vasculitis that results in tissue injury. The present integrated computational approach provides a systems approach toward identifying cell-defined functional networks that contribute to host defense and immunopathology at the site of human infectious disease.

Association between STR -794 CATT5-8 and SNP -173 G/C polymorphisms in the MIF gene and Lepromatous Leprosy in Mestizo patients of western Mexico.

Lepromatous Leprosy (LL) is the most common presentation of leprosy in Mexico. LL patients are unable to activate an effective inflammatory response against Mycobacterium leprae probably due to the genetics of the host. Macrophage Migration Inhibitory Factor (MIF) is important to trigger inflammation processes. Two polymorphisms have been reported for human MIF: STR -794 CATT5-8 and SNP -173 G/C. 7-8 CATT repeats at -794 and the C allele at -173 increase the expression of MIF. We aim to determine the association between the polymorphisms in MIF gene and LL. We carried a case and controls study with 100 Mexican LL patients and 100 healthy subjects (HS). PCR was used for genotyping of STR -794 CATT5-8 polymorphism and PCR-RFLP for -173 G/C. We found that LL patients possess high -794 CATT repeats (47.1%) more often than HS (32.7%). In conclusion, a MIF polymorphism is associated with susceptibility to LL in Western Mexican population.

In situ expression of M2 macrophage subpopulation in leprosy skin lesions.

The clinical manifestations of the leprosy depend on host immune response and the macrophages are the primary cells involved in this process. M1 and M2 cells exhibited distinct morphology, distinct surface marker profiles, as well as different cytokine and chemokine secretion. Macrophages express receptors such as CD163, CD68, CD206, and costimulatory molecules such as CD80 and CD86, and cytokines that trigger a suppressive or inflammatory response. Thirty-three untreated patients were selected, 17 patients had the tuberculoid leprosy (TT) and 16 had the lepromatous leprosy (LL). We performed immunohistochemistry to detect IL-13, IL-10, TGF-ß, FGF-ß, CD163, CD68, arginase 1. M2 macrophages showed significant differences between the groups studied with increase in the expression of costimulatory molecules (CD68 and CD163), arginase 1 and cytokines (IL-10, IL-13, TGF-ß and FGF-b) in the LL form. Response of M2 macrophages emerge as an alternative for a better understanding of the innate immunity in the polar forms of leprosy, highlighting the role of cytokines, arginase 1 and costimulatory molecules in the repair and suppressive responses in the lepromatous form of the disease.

Úlcera de Buruli. Una enferfermad "menos" olvidada / No disponible

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Examining ERBB2 as a candidate gene for susceptibility to leprosy (Hansen’s disease) in Brazil

Leprosy remains prevalent in Brazil. ErbB2 is a receptor for leprosy bacilli entering Schwann cells, which mediates Mycobacterium leprae-induced demyelination and the ERBB2 gene lies within a leprosy susceptibility locus on chromosome 17q11-q21. To determine whether polymorphisms at the ERBB2 locus contribute to this linkage peak, three haplotype tagging single nucleotide polymorphisms (tag-SNPs) (rs2517956, rs2952156, rs1058808) were genotyped in 72 families (208 cases; 372 individuals) from the state of Pará (PA). All three tag-SNPs were associated with leprosy per se [best SNP rs2517959 odds ratio (OR) = 2.22; 95% confidence interval (CI) 1.37-3.59; p = 0.001]. Lepromatous (LL) (OR = 3.25; 95% CI 1.37-7.70; p = 0.007) and tuberculoid (TT) (OR = 1.79; 95% CI 1.04-3.05; p = 0.034) leprosy both contributed to the association, which is consistent with the previous linkage to chromosome 17q11-q21 in the population from PA and supports the functional role of ErbB2 in disease pathogenesis. To attempt to replicate these findings, six SNPs (rs2517955, rs2517956, rs1810132, rs2952156, rs1801200, rs1058808) were genotyped in a population-based sample of 570 leprosy cases and 370 controls from the state of Rio Grande do Norte (RN) and the results were analysed using logistic regression analysis. However, none of the associations were replicated in the RN sample, whether analysed for leprosy per se, LL leprosy, TT leprosy, erythema nodosum leprosum or reversal reaction conditions. The role of polymorphisms at ERBB2 in controlling susceptibility to leprosy in Brazil therefore remains unclear.

Examining ERBB2 as a candidate gene for susceptibility to leprosy (Hansen's disease) in Brazil.

Leprosy remains prevalent in Brazil. ErbB2 is a receptor for leprosy bacilli entering Schwann cells, which mediates Mycobacterium leprae-induced demyelination and the ERBB2 gene lies within a leprosy susceptibility locus on chromosome 17q11-q21. To determine whether polymorphisms at the ERBB2 locus contribute to this linkage peak, three haplotype tagging single nucleotide polymorphisms (tag-SNPs) (rs2517956, rs2952156, rs1058808) were genotyped in 72 families (208 cases; 372 individuals) from the state of Pará (PA). All three tag-SNPs were associated with leprosy per se [best SNP rs2517959 odds ratio (OR) = 2.22; 95% confidence interval (CI) 1.37-3.59; p = 0.001]. Lepromatous (LL) (OR = 3.25; 95% CI 1.37-7.70; p = 0.007) and tuberculoid (TT) (OR = 1.79; 95% CI 1.04-3.05; p = 0.034) leprosy both contributed to the association, which is consistent with the previous linkage to chromosome 17q11-q21 in the population from PA and supports the functional role of ErbB2 in disease pathogenesis. To attempt to replicate these findings, six SNPs (rs2517955, rs2517956, rs1810132, rs2952156, rs1801200, rs1058808) were genotyped in a population-based sample of 570 leprosy cases and 370 controls from the state of Rio Grande do Norte (RN) and the results were analysed using logistic regression analysis. However, none of the associations were replicated in the RN sample, whether analysed for leprosy per se, LL leprosy, TT leprosy, erythema nodosum leprosum or reversal reaction conditions. The role of polymorphisms at ERBB2 in controlling susceptibility to leprosy in Brazil therefore remains unclear.

Type I interferon suppresses type II interferon-triggered human anti-mycobacterial responses.

Type I interferons (IFN-α and IFN-ß) are important for protection against many viral infections, whereas type II interferon (IFN-γ) is essential for host defense against some bacterial and parasitic pathogens. Study of IFN responses in human leprosy revealed an inverse correlation between IFN-ß and IFN-γ gene expression programs. IFN-γ and its downstream vitamin D-dependent antimicrobial genes were preferentially expressed in self-healing tuberculoid lesions and mediated antimicrobial activity against the pathogen Mycobacterium leprae in vitro. In contrast, IFN-ß and its downstream genes, including interleukin-10 (IL-10), were induced in monocytes by M. leprae in vitro and preferentially expressed in disseminated and progressive lepromatous lesions. The IFN-γ-induced macrophage vitamin D-dependent antimicrobial peptide response was inhibited by IFN-ß and by IL-10, suggesting that the differential production of IFNs contributes to protection versus pathogenesis in some human bacterial infections.

Netherton's syndrome and lepromatous leprosy: a mere coincidence?

OBJECTIVES: Netherton's syndrome (NS) is a rare autosomal recessive condition, first described in 1958, which involves a complex immunological dysfunction, ichthyosiform dermatitis, and erythroderma, characteristic defects of the hair shaft and atopy. Recurrent bacterial infection in the skin of patients with NS is frequent. METHODS: This paper represents the first case report of leprosy and concurrent NS. DISCUSSION: This case merits discussion among doctors in endemic and non-endemic areas to evaluate the chronic use of systemic corticosteroids as a risk factor for leprosy. The present patient came from an endemic area of leprosy and was treated chronically with systemic corticosteroids for erythroderma. This treatment, along with the immunodeficiency related to the syndrome and caused by a genetic mutation in SPINK5, may be a facilitating factor for the infection.

Susceptibility to leprosy is associated with M-ficolin polymorphisms.

PURPOSE: Mycobacterium leprae exploits complement activation and opsonophagocytosis to infect phagocytes. M-ficolin is encoded by the FCN1 gene and initiates the lectin pathway on monocyte surfaces. We investigated FCN1 promoter polymorphisms that could be responsible for the high interindividual variability of M-ficolin levels and for modulating leprosy susceptibility. METHODS: We genotyped rs2989727 (-1981 G > A), rs28909068 (-791 G > A), rs10120023 (-542 G > A), rs17039495 (-399 G > A), rs28909976 (-271IndelT), rs10117466 (-144C > A) and rs10858293 (+33 T > G) in 400 controls and 315 leprosy patients from Southern Brazil, and in 296 Danish healthy individuals with known M-ficolin levels. RESULTS: Ten haplotypes were identified with sequence-specific PCR and/or haplotype-specific sequencing. We found evidence for a protective codominant additive effect of FCN1*-542A-144C with leprosy in Euro-Brazilians (P=0.003, PBf =0.021, OR=0.243 [CI95% =0.083-0.71]), which was independent of age, ethnic group and gender effects (P=0.029). There was a trend for a positive association of the -399A variant in Afro-Brazilians (P=0.022, PBf =0.154, OR=4.151 [CI95% =1.115-15.454], as well as for a negative association of the FCN1*3A haplotype with lepromatous leprosy, compared with less severe forms of the disease (P=0.016, PBf =0.112, OR=0.324 [CI95% =0.123-0.858]). Danish individuals with this haplotype presented M-ficolin levels higher than the population average of circa 1,000 ng/ml, and -542A-144C, which is able to modify the recognition of transcription factors in silico, occurred in individuals with levels under the 25 percentil (P=0.031). CONCLUSIONS: Our data provide the first evidence that FCN1 polymorphisms are associated with leprosy. M-ficolin may represent a novel key to understand the immunopathogenesis of M. leprae infection.

Lack of effects of the TNF-alpha and IL-10 gene polymorphisms in Mexican patients with lepromatous leprosy.

Several human genetic variants have been associated with susceptibility or resistance to leprosy. The aim of this study was to assess whether gene polymorphisms of -308 G/A TNF-alpha and -819 T/C IL-10 are associated with lepromatous leprosy in Mexican mestizos patients from northwest Mexico. We genotyped these polymorphisms by means of polymerase chain reaction (PCR) and restriction fragment length polymorphisms (RFLPs) in 68 patients with lepromatous leprosy and 144 healthy Mexican Mestizos controls. We found that the -308G TNF-alpha allele was predominant in both cases (94.3%) and controls (92.3%) without statistical significance and the frequencies of -819C IL-10 allele were also similar for the cases (56.0%) and controls (59.0%). These negative findings suggest that other genes or polymorphisms may be important in the susceptibility to leprosy infection in the Mexican mestizos.

Genome-wide association study of skin complex diseases.

Complex diseases are caused by both genetic and environmental factors. Over decades, scientists endeavored to uncover the genetic myth of complex diseases by linkage and association studies. Since 2005, the genome-wide association study (GWAS) has been proved to be the most powerful and efficient study design thus far in identifying genetic variants that are associated with complex diseases. More than 230 complex diseases and traits have been investigated by this approach. In dermatology, 10 skin complex diseases have been investigated, a wealth of common susceptibility variants conferring risk for skin complex diseases have been discovered. These findings point to genes and/or loci involved in biological systems worth further investigating by using other methodologies. Certainly, as our understanding of the genetic etiology of skin complex diseases continues to mature, important opportunities will emerge for developing more effective diagnostic and clinical management tools for these diseases.