Mapping susceptibility genes for asthma and allergy

Developments in the field of allergy mechanisms in 2015 through the eyes of Clinical & Experimental Allergy

In the first of two papers we described the development in the field of allergy mechanisms as described by Clinical and Experimental Allergy in 2015. Experimental models of allergic disease, basic mechanisms, clinical mechanisms and allergens are all covered. A second paper will cover clinical aspects.

Analysis of the conformation and thermal stability of the high-affinity IgE Fc receptor β chain polymorphic proteins

The high-affinity IgE Fc receptor (FcεRI) β chain acts as a signal amplifier through the immunoreceptor tyrosine-based activation motif in its C-terminal intracellular region. Polymorphisms in FcεRI β have been linked to atopy, asthma, and allergies. We investigated the secondary structure, conformation, and thermal stability of FcεRI β polymorphic (β-L172I, β-L174V, and β-E228G) proteins. Polymorphisms did not affect the secondary structure and conformation of FcεRI β. However, we calculated Gibbs free energy of unfolding (ΔGunf) and significant differences were observed in ΔGunf values between the wild-type FcεRI β (β-WT) and β-E228G. These results suggested that β-E228G affected the thermal stability of FcεRI β. The role of β-E228G in biological functions and its involvement in allergic reactions have not yet been elucidated in detail; therefore, differences in the thermal stability of β-E228G may affect the function of FcεRI β.

Uteroglobulin-related protein 1 and severity of respiratory syncytial virus infection in children admitted to hospital

There are several reports suggesting that genetic factors contribute to the severity of infection with the respiratory syncytial virus (RSV). Infants hospitalized with lower respiratory tract infection (LRTI) due to RSV are at a significantly increased risk for both recurrent wheezing and childhood asthma. Uteroglobin-related protein 1 (UGRP1) is a secretory protein expressed in the airways, and speculated to have anti-inflammatory activity. The presence of the -112G/A polymorphism in the UGRP1 promoter was found to have a significant correlation with asthma phenotype. Also plasma UGRP1 levels were shown to be associated both with this polymorphism and the severity of asthma. The study population consisted of 62 previously healthy infants, ≤12 months of age, who were hospitalized with RSV LRTI, and a control group of 99 healthy adults. Genotyping was performed by restriction fragment length polymorphism. UGRP1 serum levels were determined using ELISA. There were no significant differences in the overall distribution of UGRP1 -112G/A polymorphism genotypes or alleles between the hospitalized infants and healthy adults. A comparison of serum UGRP1 concentration measured at the time of admission and discharge between patients with and without the -112A allele revealed that there was no relation between the presence of the -112A allele and serum UGRP1 in hospitalized infants with RSV infection. Furthermore, there was no relationship between severity of RSV infection and genotype or serum UGRP1 concentration. These results suggest that UGRP1 does not have a major role in the development of severe RSV infection.

Plasma UGRP1 levels associate with promoter G-112A polymorphism and the severity of asthma

BACKGROUND

Uteroglobin-related protein 1 (UGRP1) is a secretory protein expressed in the airways and is speculated to have anti-inflammatory activity. In the mouse, its gene expression is down-regulated by interleukin (IL)-5 and -9, and up-regulated by IL-10. However, the precise role of UGRP1 in human inflammatory airway diseases such as asthma has not been clarified. The objectives of this study were to establish an ELISA system to quantify UGRP1 protein, and to examine whether plasma UGRP1 levels are associated with the G-112A polymorphism, asthma susceptibility, and its severity.

METHODS

152 asthma patients and 103 normal controls were involved in this study. Mice were immunized with recombinant UGRP1 and hybridoma cell lines were established. A sandwich ELISA system was established by using two monoclonal antibodies recognizing different epitopes. Plasma UGRP1 levels were measured with the ELISA system and the G-112A allele was detected by using real-time PCR.

RESULTS

An ELISA system was established that allowed determination of UGRP1 levels within the range of 9.6-1250 pg/ml. The mean plasma UGRP1 levels for subjects with -112A allele were significantly lower than those without it (p = 0.025). Although there was no significant difference in the plasma UGRP1 levels between asthma patients and controls (p = 0.13), severe asthma patients without oral corticosteroid had significantly lower plasma UGRP1 levels compared to mild- or moderate- asthma patients and controls (p = 0.004, 0.03 and 0.003, respectively).

CONCLUSIONS

The ELISA system for quantifying UGRP1 protein was established, and plasma UGRP1 levels were associated with the G-112A UGRP1 gene promoter polymorphism and the severity of asthma.

AluyMICB dimorphism within the class I region of the major histocompatibility complex is associated with asthma and airflow obstruction in the Busselton population

AIM

To examine the association between the Alu dimorphism within the first intron of the MICB gene and asthma and airflow obstruction. Background The highly polymorphic non-classical MHC class I polypeptide-related (MIC) genes, MICA and MICB, encode stress inducible glycoproteins, which are expressed on a variety of epithelial cells, including those of the lungs.

METHODS

AluyMICB genotyping was performed on 1109 subjects from the Busselton Health Study. From a standard questionnaire, 359 individuals indicated that they had been diagnosed by a doctor with asthma. Lung function was assessed by the forced expired volume in 1 second (FEV1) and expressed as a percent of the predicted value. Airflow obstruction was defined as FEV1<80% predicted.

RESULTS

In men, a dominant relationship was found between the AluyMICB DD genotype and asthma (P=0.006; chi2(2)=7.65). Furthermore, multivariate analysis adjusted for age, height, weight and body mass index (BMI) showed a relationship between DD genotype and asthma in men in a dominant model (odds ratio (OR)=1.97; 95% confidence interval (CI)=1.11-3.51; P=0.021). In women, an association was found between the AluyMICB II genotype and FEV1 percent predicted as a continuous variable (P=0.001). When adjusted for age and BMI, it showed a significant relationship between AluyMICB and airflow obstruction in a dominant model (OR=14.11%, 95% CI 3.29-60.57, P<0.001). However, no association was found between the AluyMICB II genotypes and airflow obstruction in men.

CONCLUSION

These findings suggest the possible involvement of a MHC class I gene in abnormal airway structure in women and airway function in men.

Prolonged topical application of tacrolimus inhibits immediate hypersensitivity reactions by reducing degranulation of mast cells

We studied the effects of prolonged topical application of tacrolimus on immediate hypersensitivity reactions. Tacrolimus, betamethasone or petrolatum was applied to the footpad of mice for up to 28 days after immunization, and the foot-swelling response to allergen was estimated. The reactions in tacrolimus-treated mice decreased significantly from day 14, while those in betamethasone-treated mice decreased significantly from day 7. Although the number of mast cells in the foot skin of each group did not differ significantly, the percentage of degranulated mast cells decreased in the tacrolimus-treated group on days 7 and 14. The TUNEL method indicated that there were no apoptotic mast cells in the foot skin of tacrolimus-treated mice. Continuous application of topical tacrolimus ointment may suppress immediate hypersensitivity reactions by reducing the degranulation of mast cells, rather than by decreasing their number.

Lack of an association between a newly identified promoter polymorphism (-1702G > A) of the leukotriene C4 synthase gene and aspirin-intolerant asthma in a Korean population

Aspirin-intolerant asthma (AIA) is a distinct clinical syndrome that refers to the development of bronchoconstriction in asthmatic individuals following the ingestion of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). It is widely recognized that increased cysteinyl leukotriene (cysLT) biosynthesis is associated with the development and progression of AIA. Leukotriene C4 synthase (LTC4S) is the terminal enzyme in cysLT production and is a strong candidate gene in the pathogenesis of aspirin-intolerant asthma (AIA). In this paper, we report a new single nucleotide polymorphism (SNP) of the LTC4S promoter, -1702G>A, in AIA patients and evaluate its genetic role in the association with the LTC4S-444 A>C polymorphism. We enrolled 110 AIA patients, 125 aspirin-tolerant asthma (ATA) patients, and 125 normal controls. SNP genotyping of the LTC4S-1702G>A and -444A>C polymorphisms was performed using SNP-IT assays. Haplotype analyses were performed using Haploview version 2.05, which is based on an estimation-maximization (EM) algorithm. There were no significant differences in the allele or genotype frequencies of the LTC4S-1702G>A and -444A>C polymorphisms among the three groups (p > 0.05), with no significant differences in the observed haplotype frequencies (p > 0.05). Moreover, no significant associations were found between the genotype of each SNP in AIA patients with the clinical characteristics, including a forced expiratory volume in one second (FEV1) %, a provocation concentration of methacholine to induce more than 20% decrease of FEV1 (PC20) to methacholine, and serum total IgE levels (p > 0.05). These results indicate that there is no association between these two promoter polymorphisms of LTC4S and the phenotype of AIA in a Korean population.

HLA antigens in Greek children with allergic bronchial asthma

The aim of our study was to investigate the genetic linkage between mite allergic bronchial asthma and HLA class I and II antigens and haplotypes. Sixty Greek children with allergic bronchial asthma due to mite sensitivity (Dermatophagoides pteronyssinus and Dermatophagoides farinae) and their family members were typed for HLA class I and II antigens (total 263 subjects). One hundred and twenty-five healthy, unrelated Greek children without medical history of atopy were also typed as control group. Major histocompatibility complex class I and II gene analysis revealed that only HLA-DRB1*04 and HLA-DQA1*0301 alleles are possibly important factors in the development of atopic asthma in Greek children with sensitivity to mites. No significant differences among the HLA-DRB1*04 subtypes have been established. Transmission disequilibrium test revealed that no specific HLA-A, -B, -DRB1, -DQA1 and -DQB1 alleles were transmitted preferentially to the affected children. HLA-DQB1*0301-4 alleles were associated with high levels of total serum immunoglobulin E in affected children. The study of the HLA haplotypes failed to demonstrate any significant association between any extended or natural selection haplotype and mite allergic bronchial asthma in Greek children.

Allergies in patients with chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome) and patients with chronic granulomatous disease

Humoral immunodeficiencies have a recognized association with atopy. This study investigated the association of a T-cell disorder (chromosome 22q11.2 deletion) and a neutrophil disorder [chronic granulomatous disease (CGD)] with asthma, eczema, and rhinitis using a standardized survey instrument. Patients were recruited from either a national referral center (chromosome 22q11.2 deletion syndrome) or from a registry (CGD). Controls consisted of siblings of patients. Chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome) was found to be significantly associated with both eczema and asthma but not allergic rhinitis. CGD was not found to be significantly associated with atopic diseases.

Single-nucleotide polymorphisms of the KCNS3 gene are significantly associated with airway hyperresponsiveness

Airway hyperresponsiveness (AHR) is one of the major clinical symptoms and intermediate phenotypes of asthma. A recent genome-wide search for asthma quantitative trait loci has revealed a significant linkage signal between a p-terminal region of chromosome 2 and AHR. Thus, the gene encoding the potassium voltage-gated channel delayed-rectifier protein S3 (KCNS3) in this region is considered a positional candidate for asthma. We have evaluated a total of 12 single-nucleotide polymorphisms (SNPs) of the KCNS3 gene in a validation panel of 48 lymphoblastoid cell line DNA samples of Chinese origin. Three SNPs were found to be polymorphic and were tested. Two independent sets (an initial screening set and a replication set) of cases and controls from the original linkage study sample were collected. In the initial screening set, two SNPs (rs1031771 and rs1031772) showed suggestive association and were further confirmed by the replication set. In combined single-SNP analysis, the rs1031771 G allele (odds ratio=1.42, P=0.006) and rs1031772 T allele (odds ratio=1.40, P=0.018) were associated with a significantly higher risk of AHR. Haplotype analysis also detected significant association (P=0.006). Our findings suggest that SNPs located at the 3' downstream region of KCNS3 have a significant role in the etiology of AHR.

Mast Cells and Hemangioma

Hemangioma is a primary tumor of the microvasculature in which angiogenesis is initially excessive, followed by spontaneous regression of the newly formed vessels, with the cellular parenchyma gradually being replaced with fibrofatty tissue. Mast cells, which are highly heterogenous in terms of their morphology, function, and metabolic products, have been implicated in the pathophysiology of hemangioma. Csaba stain shows that mast cells are predominantly of the biogenic amine phenotype throughout the development of hemangioma. The predominance of this phenotype remains unaltered following successful steroid therapy, although their number increases fourfold. Mast cells, all of which stain positive for tryptase, and those that stain positive for chymase as well, have been identified in hemangioma biopsy specimens throughout the three developmental phases. The total number of mast cells is highest during the involuting phase, less in the involuted phase, and least in the proliferative phase. The proportion of mast cells that contain both tryptase and chymase decreases from the proliferative through involuting to the involuted phase. This decreasing proportion of mast cells that contain both tryptase and chymase with ongoing involution parallels that of progressive deposition of the extracellular matrix as indicated by increasing fibrosis and fatty deposition. The short-chain type VIII collagen, thought to play a key role in angiogenesis, has been detected throughout the developmental phases of hemangioma. It has been postulated that this collagen, which is produced early in new vessel development, provides a substratum to facilitate the migration of endothelial cells. It may also facilitate the deposition of other extracellular constituents and influence cell movement and the maintenance of cell phenotypes. The intracellular localization of type VIII collagen in mast cells only in the early proliferative phase suggests that there is an active synthesis by mast cells during this phase. The increasing extracellular localization during hemangioma development may be caused by an increased secretion of protein from intracellular stores. The increased number of mast cells during the involuting phase indicates that these cells may play a role in the regression of hemangioma. This is in contrast to the large body of evidence showing the proangiogenic role of mast cells. The proportion of proliferating mast cells decreases, whereas the proportion of mast cells positive for clusterin/apolipoprotein J increases with ongoing involution of hemangioma. Clusterin/apolipoprotein J expression has been considered as a prominent marker of apoptotic cell loss. The presence of clusterin/apolipoprotein J granules both in the adjacent endothelial cells and in capillary lumens suggests that mast cells may be secreting this apoptotic modulator to promote the regression of hemangioma. Certain effectors produced by mast cells may participate in the development of hemangioma. It has been proposed that one of the functions of mast cells is to release factors leading to the regression of hemangioma. The evidence suggests that although mast cells may have a function in the endothelial proliferation in hemangioma, they also play a crucial role in the regression of this tumor. However, the roles of mast cells in the life cycle of hemangioma are likely to be complex and may involve stimulators of angiogenesis in the proliferative phase but inhibitors in later phases.

Epidemiological studies of the very high prevalence of asthma and related symptoms among school children in Costa Rica from 1989 to 1998

The aim of our study was to determine the prevalence of asthma and related respiratory symptoms in school children from Costa Rica during the last 10 years, from 1989 to 1998. Using nationally representative samples of school children from Costa Rica during the last 10 years we have performed three studies. Altogether 9,931 children were investigated. The age groups: study I, 5-17 years (n = 2,682), study II, 6-7 years (n = 2,944), 13-14 years (n = 3,200) and study III, 10 years (n = 1,105). The diagnostic criteria for asthma used in these studies was as follows: study I (1989), diagnosis by a doctor in combination with the presence of four kinds of respiratory symptoms; studies II (1995) and III (1998), history of wheeze in the past 12 months. The two latter were part of the International Study of Asthma and Allergies in Childhood (ISAAC). A very high prevalence of a history of wheezing was found in the three studies (46.8%, 42.9%, and 45.1%) as well as a diagnosis of asthma (23.4%, 27.7% and 27.1%). The physician's diagnosis of asthma reported in the first study (23%) increased from 23.1 in study II to 27.7% in study III (p = 0.004). This increment could be a real increase in asthma prevalence, or be due to a better awareness about asthma. In study II the group of 6-7-year-olds had respiratory symptoms significantly more often than 13-14-year-olds (p < 0.001). Boys more often had a history of wheezing (p = 0.001), wheeze during the previous 12 months (p = 0.01) and an asthma diagnosis at the age of 6-7 years (p = 0.002) than girls, but girls had more respiratory symptoms than boys at the age of 13-14 years (p < 0.005). Wheezing in the past 12 months was more common for those living in urban areas aged 6-7 years (p = 0.04), and there was an increase of wheeze after exercise (p = 0.01). For the 13-14-year-olds the risk of wheezing was higher during the previous 12 months if they lived in temperate areas (<20 degrees C) and at a high altitude (>1,000 m). Living in a rural area and in a warm region (>20 degrees C), increased the risk of dry cough during the previous 12 months in the group of 13-14-year-olds. In conclusion, Costa Rica is located in the tropics with a very high humidity, an enormous variety of flora and fauna and a very high prevalence of mite and cockroach allergens, which provide important risk factors that may explain the high prevalence of asthma and asthma-related symptoms. Further possible factors, such as the change towards a more Western life style, resulting in fewer infections and parasitic diseases in the first years of life and changes in bedding material, may also be unresolved. Increased environmental pollution may add to the very high prevalence of asthma and related respiratory symptoms. The very extensive exposure to mites and cockroaches in bed material and in homes with poor ventilation may be an important factor, but many asthmatic children behave as non atopic, with a viral respiratory infection as a major precipitating factor.

A polymorphism in the human UGRP1 gene promoter that regulates transcription is associated with an increased risk of asthma

Several traits associated with asthma phenotypes, such as high total serum immunoglobulin E and bronchial hyperresponsiveness, have been linked by numerous genome-screen studies and linkage analyses to markers on human chromosome 5q31-q34. In the present article, we describe UGRP1 (encoding uteroglobin-related protein 1) as one of asthma-susceptibility genes that is located on chromosome 5q31-q32. UGRP1 is a homodimeric secretory protein of 17 kDa and is expressed only in lung and trachea. The G --> A polymorphism was identified at -112 bp in the human UGRP1 gene promoter. The -112A allele is responsible for a 24% reduction in the promoter activity in relation to the -112G allele, as examined by transfection analysis. Electrophoretic mobility-shift analysis revealed that an unknown nuclear factor binds to the region around -112 bp. The binding affinity with the -112A oligonucleotide was reduced by approximately one half, as compared with the -112G oligonucleotide. In a case-control study using 169 Japanese individuals (84 patients with asthma and 85 healthy control individuals), those with a -112A allele (G/A or A/A) were 4.1 times more likely to have asthma than were those with the wild-type allele (G/G).

PAF acetylhydrolase gene polymorphisms and asthma severity

This review describes the current understanding of the contributions of genetic alterations in platelet-activating factor (PAF) acetylhydrolase to the pathogenesis of asthma. A variety of in vitro and in vivo studies, performed by multiple laboratories, suggest that the lipid substrates of this enzyme, PAF and oxidised derivatives of phosphatidylcholines, play important roles as causative factors in many diseases including asthma. PAF acetylhydrolase inactivates PAF and oxidatively-fragmented lipids thus providing a mechanism to prevent their pro-inflammatory effects. Since it is a most unusual protein, the biochemical, structural and functional characteristics of PAF acetylhydrolase continue to be unravelled. First, the ability of this enzyme to inactivate pro-inflammatory lipid mediators is modulated by its association with lipoproteins and by its susceptibility to oxidative inactivation. Second, mediators of inflammation, such as the substrates for PAF acetylhydrolase, alter expression of the protein at the transcriptional level. Third, naturally-occurring variants of PAF acetylhydrolase have catalytic properties different from those exhibited by the most common form of this protein. Thus, a variety of factors, including genetics, contribute to determine the biological level of lipid substrates known to act as mediators of asthma and other diseases. Here, I summarise key studies that implicate PAF and related molecules as important mediators in the pathogenesis of asthma. Next, I describe clinical findings that are consistent with a role of PAF acetylhydrolase as a modulator of asthma. Third, I focus on the biochemical effects associated with naturally-occurring mutations and polymorphisms in the PAF acetylhydrolase gene and the incidence of these genetic variations in populations of asthmatic subjects. Finally, I present my views on the future of this emerging field and the potential utility of performing additional studies aimed at further characterising the contribution of PAF acetylhydrolase to the pathogenesis of a complex syndrome generally recognised as a multifactorial and heterogeneous disease.

What are the most promising strategies for the therapeutic immunomodulation of allergic diseases?

Specific immunotherapy and other immunomodulatory strategies have long been a stronghold in the management of allergic diseases. In particular, "immunodeviation-therapy" or "vaccination for allergies", i.e. the redirection of Th2-type immune responses towards a Th1-response pattern, has become an ever more popular concept. The present feature of CONTROVERSIES complements our previous discussion of atopy (Röcken et al., Exp Dermatol 7: 97--104, 1998), and is dedicated to a critical analysis of the general problems and limitations one faces with the main immunomodulatory strategies traditionally considered in this context. We also explore alternative approaches that appear promising in order to achieve both a more effective and/or a more specific immunotherapy of allergic diseases. Given that the mast cell remains a key protagonist in the pathogenesis of allergic diseases finally, this feature examines how innovative, more selectively mast cell-targeted strategies may be developed for the management of allergic diseases.

Revisiting the roles of mast cells in allergic rhinitis and its relation to local IgE synthesis

Mast cells are important effector cells in the immediate-phase allergic reaction. However, in recent years much evidence has accumulated on the versatile role of mast cells in allergic inflammation. The present article is an overview of the roles of mast cells in allergic inflammation, especially in light of the local production of IgE and the IgE-IgE receptor network. Although both nasal mast cells (NMC) and T cells in allergic rhinitics are important sources of Th2-type cytokines like IL-4 and IL-13, and can induce IgE synthesis, we report here that antigen-activated NMC can secrete greater levels of IL-4/IL-13 and induce increased levels of IgE synthesis than antigen-activated nasal T cells. Furthermore, IgE production can occur locally in the nasal mucosa (target organ) and IgE itself can enhance the Fc epsilon RI expression and subsequent mediator release from NMC, thus contributing to the perpetuation of on-going allergic inflammation. Again, mast cells can contribute to the late-phase allergic reaction not only via the upregulation of adhesion molecules like VCAM-1, but also through the interactions of NMC with the extracellular matrix proteins, and interaction of NMC with nasal epithelial cells (NEC). Thus, it is increasingly evident that mast cells are not only important for the genesis of the allergic reaction, but also contribute to the late-phase allergic reaction and on-going allergic inflammation.

Genetics of rat neuroinflammation

The definition of genes regulating the pathogenetic pathways of autoimmune neuroinflammation, may provide targets for new therapeutic strategies. This is not easily accomplished in human disease. Such genetic dissection can more readily be done by the use of inbred rodent strains. With these, genetic heterogeneity is avoided and variation in the environmental influences is minimized. Close mimicking of the human disease characteristics is desirable in such endeavors. Chronic relapsing experimental autoimmune encephalomyelitis (EAE) with MS-like histopathology is achieved after immunization of certain rat strains with myelin oligodendrocyte glycoprotein (MOG) or spinal cord homogenate. The major histocompatibility complex (MHC) regulate the ease by which the environmental trigger in the form of immunisation induces disease. Use of intra-MHC recombinant strains demonstrated major influences from the MHC class II genome region, but additional influences from both the MHC class I and III regions. These findings now provide a basis for studies of the mechanisms for MHC-controlled autoimmune pathogenicity leading to MS-like disease. Gene mapping of F2 crosses between susceptible and resistant rat strains demonstrated nine genome regions outside the MHC which regulate different phenotypes of rat EAE. Many of these co-localize with genome regions regulating other organ-specific disease such experimental arthritis, suggesting a sharing of disease pathways. Further finemapping can lead to the exact identification of disease regulating genes. Interestingly, we have also demonstrated a non-MHC gene control of the inflammatory response, in the form of glial cell activation, and neuronal degeneration, subsequent to anterior nerve root avulsion in rats. The genetic dissection of these influences may unravel pathways controlling CNS vulnerability.

Polymorphisms in FcepsilonRI beta chain do not affect IgE-mediated mast cell activation

Genetic polyymorphisms that result in three amino acid changes in FcepsilonRI beta chain (Ile(181)-->Leu, Val(183)-->Leu, and Glu(237)-->Gly) have been identified as candidates that associate with allergic disorders such as atopy and asthma. To elucidate the biological significance of these polymorphisms in regulating the expression and function of FcepsilonRI, we generated four types of transfectants that express wild-type or mutant mouse beta chains corresponding to these human variants by retrovirus-mediated gene transfer into beta chain-deficient mouse-derived mast cells. No significant functional differences between the wild-type beta chain transfectant and any of the mutant beta chain transfectants were observed in beta-hexosaminidase release, intracellular calcium mobilization, or cytokine and leukotriene C(4) production in response to FcepsilonRI crosslinking. Our results suggest that these polymorphisms in FcepsilonRI beta chain do not affect FcepsilonRI-mediated mast cell activation at least in our mouse in vitro system.

Linkage of familial moyamoya disease (spontaneous occlusion of the circle of Willis) to chromosome 17q25

BACKGROUND AND PURPOSE

Moyamoya disease is a cerebrovascular disease of unknown cause that mainly affects Japanese children. The incidence of familial occurrence accounts for 9% of cases. The characteristic lesions of moyamoya disease are occasionally seen in neurofibromatosis type 1, of which the causative gene (NF1) has been assigned to chromosome 17q11.2.

METHODS

To determine whether a gene related to moyamoya disease is located on chromosome 17, we conducted microsatellite linkage analyses on 24 families containing 56 patients with moyamoya disease. Leukocyte DNA extracted from the family members was subjected to polymerase chain reaction for a total of 22 microsatellite markers on chromosome 17. The amplified polymerase chain reaction fragments were analyzed with GeneScan on an automated sequencer.

RESULTS

Two-point linkage analysis gave a maximum log(10) odds (LOD) score of 3.11 at the recombination fraction of 0.00 for the marker at locus D17S939. The affected pedigree member method also showed a significantly low P value (<1. 0x10(-5)) for the 5 adjacent markers at 17q25. Multipoint linkage analysis also indicated that the disease gene is contained within the 9-cM region of D17S785 to D17S836, with a maximum LOD score of 4. 58.

CONCLUSIONS

A gene for familial moyamoya disease is located on chromosome 17q25.

The ultrastructural patterns of mast cell degranulation in Kimura's disease

BACKGROUND

Although Kimura's disease has been considered an atopic disease because of the association of peripheral blood eosinophilia and elevated serum IgE, the mechanisms of these phenomena are still unknown.

OBJECTIVE

It is now established that mast cells are a source of cytokines that are involved in eosinophil recruitment or IgE production. In order to understand the role of mast cells in Kimura's disease, we conducted ultrastructural studies.

METHOD

The 45 mast cells obtained from 2 patients with Kimura's disease were classified into two subgroups: S type, with a predominance of scroll or crystal subelements in their granules, and P type, predominantly possessing a particulate or filamentous substructure.

RESULTS

We observed numerous P type mast cells with focal losses of granule contents in the absence of granule extrusion in Kimura's disease.

CONCLUSION

These results indicate the possibility that slow release of mediators or cytokines from mast cells by piecemeal degranulation may contribute to the pathomechanism of Kimura's disease.