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Immunogenetic profile of psoriasis vulgaris: association with haplotypes A2,B13,Cw6,DR7,DQA1*0201 and A1,B17,Cw6,DR7,DQA1*0201.

Psoriasis vulgaris is a skin disease with an immunological and genetic background present in 1-3% of the population. We studied the genetic susceptibility to psoriasis vulgaris in Finns with serological HLA typing and genomic HLA class II typing of the DQ and DP loci to evaluate the risk of developing psoriasis. The haplotypes most frequently distinguishing between psoriatics and controls were those that carried Cw6 (P < 10(-8)), DQA1*0201 (P = 9.3 x 10(-6)) and DR7 (P = 3.9 x 10(-5)). The two most frequent marker haplotypes were A2,B13,Cw6,DR7, DQA1*0201 and A1,B17,Cw6,DR7,DQA1*0201, which were not found among the control subjects. A deficit of haplotype B8,DR3,DQ2 (2 out of 124 in the patients versus 15 out of 106 in the controls, P = 1.5 x 10(-4)) was found, and this was in accordance with a slightly decreased frequency of DQA1*0501 (P = 3.1 x 10(-2)), which was usually linked with this haplotype. These results stimulate the research for a genetic resistance factor in psoriasis. Thus, this report sheds further light on the immunogenetic background of psoriasis in Finland. We conclude that the inheritance of psoriasis has a polygenic mode, in which the Cw6,DR7,DQA1*0201 combination seems to be important (P = 7.5 x 10(-7), relative risk 24.4, aetiological factor 0.29).

Adult↗

Immuno- and genetic therapy in autoimmune diseases.

Animal models of autoimmune disease have been developed that mimic some aspects of the pathophysiology of human disease. These models have increased our understanding of possible mechanisms of pathogenesis at the molecular and cellular level and have been important in the testing, development and validation of new immunotherapies. The susceptibility to develop disease in the majority of these models is polygenic as is the case in humans. The exceptions to this rule are gene knock outs and transgenic models of particular genes which, in particular genetic backgrounds, have also contributed to the understanding of single gene function and their possible contribution to pathogenesis. Gene therapy approaches that target immune functions are being developed with encouraging results, despite the polygenic nature of these diseases. Basically this novel immuno-genetic therapy harnesses the knowledge of immunology with the myriad of biotechnological breakthroughs in vector design and delivery. Autoimmune disease is the result of genetic dysregulation which could be controlled by gene therapy. Here we summarize the genetic basis of these human diseases as well as some of the best characterized murine models. We discuss the strategies for their treatment using immuno- and gene therapy.

Animals↗

Recombinant inbred and congenic strains of the rat for genetic analysis of limb morphogenesis.

Recombinant inbred (RI) and congenic strains carrying the polydactyly-luxate syndrome (PLS) provide an experimental model for the analysis of polygenic control of limb development. PLS is determined by a major gene Lx whose phenotypic expression is strongly influenced by the genetic background upon which it operates. The morphometric analysis of the skeleton of front and hind legs has been carried out. The morphotypes of PLS in RI strains exhibit a continuous variability and transgressive variation compared to BN.Lx and SHR.Lx morphotypes, which strongly indicates the polygenic effects on PLS manifestation. Quantitative trait loci (QTL) were searched for through correlation of genetic markers and morphometric traits. The association analysis revealed statistically significant correlations (P < 0.0003) of morphometric traits with two markers on chromosome 4 (Il6 and A2m) associated with the number of front feet and hind feet phalanges, respectively, one marker on chromosome 7 (D7Mit17) associated with the tibia length, and the somatostatin gene on chromosome 11 associated with the number of front feet phalanges. In addition, suggestive associations of morphometric traits with markers on further nine chromosomes have been found (correlation coefficients ranging from 0.5 to 0.6). The verification of all these findings is in progress by means of double congenic strains which, in addition to the Lx gene, carry differential chromosome segments with putative modifiers.

Animals↗

The metabolic syndrome: the crossroads of diet and genetics.

The metabolic syndrome is a very common disease associated with an increased risk of type 2 diabetes mellitus (T2DM) and CVD. The clinical characteristics of the metabolic syndrome include insulin resistance, dyslipidaemia, abdominal obesity and hypertension. The diverse clinical characteristics illustrate the complexity of the disease process, which involves several dysregulated metabolic pathways. Thus, multiple genetic targets must be involved in the pathogenesis and progression of the metabolic syndrome. Nevertheless, the human genome has not changed markedly in the last decade but the prevalence of the metabolic syndrome has increased exponentially, which illustrates the importance of gene-environmental interactions. There is good evidence that nutrition plays an important role in the development and progression of the metabolic syndrome. Indeed, obesity is a key aetiological factor in the development of the metabolic syndrome. Understanding the biological impact of gene-nutrient interactions will provide a key insight into the pathogenesis and progression of diet-related polygenic disorders, including the metabolic syndrome. The present paper will explore the interactions between genetic background and dietary exposure or nutritional therapy, focusing on the role of dietary fatty acids within the context of nutrient regulation of gene expression and individual responsiveness to dietary therapy. Only with a full understanding of gene-gene, gene-nutrient and gene-nutrient-environment interactions can the molecular basis of the metabolic syndrome be solved to minimise the adverse health effects of obesity and reduce the risk of the metabolic syndrome, and subsequent T2DM and CVD.

Diet↗

Char syndrome, an inherited disorder with patent ductus arteriosus, maps to chromosome 6p12-p21.

BACKGROUND: Patent ductus arteriosus (PDA) is a relatively common form of congenital heart disease. Although polygenic inheritance has been implicated, no specific gene defects causing PDA have been identified to date. Thus, a positional cloning strategy was undertaken to determine the gene responsible for the Char syndrome, an autosomal dominant disorder characterized by PDA, facial dysmorphism, and hand anomalies. METHODS AND RESULTS: A genome scan was performed with 46 members of 2 unrelated families in which the disease was fully penetrant but the phenotype differed. Significant linkage was achieved with several polymorphic DNA markers mapping to chromosome 6p12-p21 (maximal 2-point LOD score of 8.39 with D6S1638 at theta=0.00). Haplotype analysis identified recombinant events that defined the Char syndrome locus with high probability to a 3. 1-cM region between D6S459/D6S1632/D6S1541 and D6S1024. CONCLUSIONS: A familial syndrome in which PDA is a common feature was mapped to a narrow region of chromosome 6p12-p21. Additional analysis with other families and polymorphic markers as well as evaluation of potential candidate genes should lead to the identification of the Char syndrome gene, which will provide insights into cardiogenesis as well as limb and craniofacial development.

Chromosome Mapping↗

Low frequency of melanocortin-4 receptor (MC4R) mutations in a Mediterranean population with early-onset obesity.

BACKGROUND: Melanocortin-4 receptor (MC4R) mutations have been reported as the most common single genetic cause of obesity in some populations and it has been suggested that they may be responsible for more than 4% of early-onset obesity. OBJECTIVES: To verify the presence of mutations of the MC4R coding region in children from southern Italy with early-onset obesity. SUBJECTS AND METHODS: Two-hundred and eight unrelated obese children and adolescents were included in the study. The average age at obesity onset was 4.5+/-2.6 y. MC4R coding region was screened using both single-strand conformation polymorphism (SSCP) analysis and denaturing high-performance liquid chromatography (DHPLC). Automatic sequencing of PCR products of all individuals that showed an aberrant SSCP and/or DHPLC pattern was performed. RESULTS: One novel missense mutation and one previously described polymorphism (Vall03Ile) were identified. The missense mutation C142T, resulting in the substitution of proline with serine at codon 48, within the first MC4R transmembrane domain, was detected at the heterozygous state in a 15-y-old obese girl (body mass index (BMI)=35 kg/m(2)) who has been obese since she was 8 y old. The mutation co-segregated with the obesity phenotype for over three generations and was not found in the control population. CONCLUSIONS: Our data show MC4R obesity causing mutations in less than 0.5% of the patients (ie 1 out of 208 patients) and therefore indicate a low prevalence of MC4R variants in the obese population from southern Italy. The specific genetic background of the Mediterranean population could make it difficult for MC4R mutations to produce an essentially polygenic trait such as common obesity, at least during childhood.

Adolescent↗

Energy balance in obesity.

The current epidemic of human obesity implies that whilst energy balance appears to be regulated, the extent of this regulatory process is being overwhelmed in large numbers of the population by environmental changes. Clearly, the shift towards positive energy balance reflects both alterations in energy intake and decreases in physical activity. Increased energy intake and, in particular, the rising proportion of energy from fat is linked with obesity. However, on a population level reduced levels of activity probably play the predominant role. It is apparent that individual susceptibility to weight gain varies enormously. The factors underlying this susceptibility are an area of intense research interest. Variations in BMR from that predicted appear to be linked to the propensity to gain weight. The genes responsible for this variation may include uncoupling proteins-2 and -3, with a number of studies showing a link with obesity. However, in vivo studies of these proteins have not yet demonstrated a physiological role for them that would explain the link with obesity. Non-exercise activity thermogenesis may also protect from weight gain, but the regulation of this type of thermogenesis is unclear, although the sympathetic nervous system may be important. A profusion of hormones, cytokines and neurotransmitters is involved in regulating energy intake, but whilst mutations in leptin and the melanocortin-3 receptor are responsible for rare monogenic forms of obesity, their wider role in common polygenic obesity is not known. Much current work is directed at examining the interplay between genetic background and environmental factors, in particular diet, that both lead to positive energy balance and seem to make it so hard for many obese subjects to lose weight.

Basal Metabolism↗

Genetic aspects of umbilical hernia incidence in cats and dogs.

The incidence of umbilical hernia in a family of Cornish rex cats approximated monogenic proportions. The genetic and developmental basis for umbilical hernia may be similar in cats and dogs. The defect is probably a polygenic threshold character, possibly involving a major gene whose expression is mediated by the genetic (breed) background.

Animals↗

Functional characterization and neuronal modeling of the effects of childhood absence epilepsy variants of CACNA1H, a T-type calcium channel.

Sequencing of the T-type Ca2+ channel gene CACNA1H revealed 12 nonsynonymous single nucleotide polymorphisms (SNPs) that were found only in childhood absence epilepsy (CAE) patients. One SNP, G773D, was found in two patients. The present study reports the finding of a third patient with this SNP, as well as analysis of their parents. Because of the role of T-channels in determining the intrinsic firing patterns of neurons involved in absence seizures, it was suggested that these SNPs might alter channel function. The goal of the present study was to test this hypothesis by introducing these polymorphisms into a human Ca(v)3.2a cDNA and then study alterations in channel behavior using whole-cell patch-clamp recording. Eleven SNPs altered some aspect of channel gating. Computer simulations predict that seven of the SNPs would increase firing of neurons, with three of them inducing oscillations at similar frequencies, as observed during absence seizures. Three SNPs were predicted to decrease firing. Some CAE-specific SNPs (e.g., G773D) coexist with SNPs also found in controls (R788C); therefore, the effect of these polymorphisms were studied. The R788C SNP altered activity in a manner that would also lead to enhanced burst firing of neurons. The G773D-R788C combination displayed different behavior than either single SNP. Therefore, common polymorphisms can alter the effect of CAE-specific SNPs, highlighting the importance of sequence background. These results suggest that CACNA1H is a susceptibility gene that contributes to the development of polygenic disorders characterized by thalamocortical dysrhythmia, such as CAE.

Calcium Channels, T-Type↗

Clinicopathological features in 102 cases of Hirschsprung disease.

BACKGROUND: Hirschsprung disease [HD] is a predominantly childhood disorder of intestinal motility with a multifactorial and polygenic etiology. The objective of this study was to document the clinical and pathological features of HD in Kuwait, which has an estimated consanguinity rate of 54%. METHODS: We analyzed all rectal and colonic biopsies (n=268) for suspected HD identified from the records in the Pathology Department of Al-Sabah Hospital for the period between 1994 and 2004. RESULTS: One hundred and two patients (87 males and 15 females) had histologically confirmed HD. Fifty-eight (57%) were neonates (<1 month of age), while 21% were more than 4 months old. The diagnosis was based on open biopsy in 11 cases and rectal biopsies in 91 cases. Nine patients with open biopsies presented as intestinal obstruction, necrotizing enterocolitis, or perforation. The extent of the disease was unknown in 13 patients. There were 67 males and 3 females with short segment HD. Nine had long segment, two ultra-short segment and eight total colonic aganglionosis (TCA). Five TCA cases involved the small intestine. A skip area was observed in two cases. Six patients had other anomalies. A positive family history for HD was established in three patients. Two of these were male siblings from a consanguineous marriage and had Waardenburg syndrome. CONCLUSION: This study has highlighted an exceptionally strong male predominance of short segment and a relatively high frequency (5.6%) of small intestinal involvement in HD in Kuwait. These data call for a more detailed epidemiological study with special emphasis on genetics.

Adolescent↗

[Predictive genetic screening for type-1 diabetes in the Hungarian population].

INTRODUCTION: In the modern genetic era the principles of genetic screening are being changed. In addition to diagnostic screening for rare monogenic diseases, predictive screening for common polygenic conditions, like type 1 diabetes, will be more widely implemented. The majority of the genetic background of type 1 diabetes is encoded by the HLA DQ and DR genes, selected variants of which could be used as screening markers. However, risk conferred by various HLA genotypes shows considerable ethnic variation, therefore population-specific screening markers need to be established. AIMS: The aim of this study was to describe a screening strategy based on risk-defining HLA DRB1-DQA1-DQB1 markers to identify individuals at risk for type 1 diabetes in the Hungarian population. METHODS: HLA genotypes of 149 consecutively diagnosed children with type 1 diabetes (age at diagnosis 0-14, mean 8.8 +/- 4.2 years) and 177 randomly selected healthy schoolchildren were studied. Allele-specific polymerase chain reaction method was used for HLA typing. The diagnostic sensitivity, specificity and predictive value of diabetes associated DRB1-DQA1-DQB1 alleles were analysed in a step-wise strategy. RESULTS: The highest diagnostic sensitivity was detected when DQB1 typing was complemented by DQA1 typing on DQB1*0201 positive samples with additional DRB1*04 subtyping in DQB1*0302 carriers. The combination of the following markers gave a relative risk of 28.9 (95% confidence interval: 15.9-52.7, p = 10(-6): DQB1*0201/0302-DQA1*0301,0501-b (b not equal to DRB1* 0403), DQB1*0302/x-DRB1*0401,0402 (not equal to DQB1*0201, 0301,0602,0603), DQB1*0301/0302-DRB1*0401,0404, DQB1*0304/s (s = any DQB1 alleles), DQB1*0201/y-DQA1*0501/a (y not equal to DQB1*0301,0302,0602, 0603,0604, a not equal to DQA1*0201). The diagnostic sensitivity, specificity and positive predictive values for this marker combination were 79.2%, 88.7%, and 1.1%, respectively. CONCLUSIONS: Using HLA DRB1-DQA1-DQB1 markers predictive genetic screening for type 1 diabetes is feasible in the Hungarian population with high diagnostic sensitivity and specificity. At present, such a screening for individuals at risk for type 1 diabetes in the general population is recommended only as part of prospective studies on the natural history or prevention of disease. To increase the positive predictive value of the model, pancreas beta-cell autoantibodies need to be measured and followed in the high-risk cohort.

Adolescent↗

Genetic studies on natural resistance to Moloney lymphoma (YAC) isografts. I. Introduction of a non-H-2-linked resistance gene on strain A/Sn background.

YAC is a Moloney-virus-induced lymphoma of strain A/Sn origin that is highly sensitive to natural killing (NK) in vitro and NK-mediated hybrid resistance in vivo. Previous studies have shown that hybrid resistance is under polygenic control that includes both H-2-linked and non-H-2-linked factors. For further analysis on the genetics and immunology of hybrid resistance, we are at present developing congenic resistant lines on an A/Sn strain background. Following an outcross to a strain that conveys strong hybrid resistance on the F1 offspring, the mice are challenged with small viable inocula of YAC. Survivors are backcrossed to A/Sn. This is followed by repeated YAC challenge and backcrossing. We now report the successful establishment of a first resistant strain, designated A.LRA. It is relatively resistant to small inocula of YAC cells due to a single, non-H-2-linked dominant gene introduced from the C57L strain.

Animals↗

Binge eating as a major phenotype of melanocortin 4 receptor gene mutations.

BACKGROUND: Obesity, a multifactorial disease caused by the interaction of genetic factors with the environment, is largely polygenic. A few mutations in these genes, such as in the leptin receptor (LEPR) gene and melanocortin 4 receptor (MC4R) gene, have been identified as causes of monogenic obesity. METHODS: We sequenced the complete MC4R coding region, the region of the proopiomelanocortin gene (POMC) encoding the alpha melanocyte-stimulating hormone, and the leptin-binding domain of LEPR in 469 severely obese white subjects (370 women and 99 men; mean [+/-SE] age, 41.0+/-0.5 years; body-mass index [the weight in kilograms divided by the square of the height in meters], 44.1+/-2.0). Fifteen women and 10 men without a history of dieting or a family history of obesity served as normal-weight controls (age, 47.7+/-2.0 years; body-mass index, 21.6+/-0.4). Detailed phenotypic data, including information on body fat, resting energy expenditure, diet-induced thermogenesis, serum concentrations of leptin, and eating behavior, were collected. RESULTS: Twenty-four obese subjects (5.1 percent) and one control subject (4 percent) had MC4R mutations, including five novel variants. Twenty of the 24 obese subjects with an MC4R mutation were matched for age, sex, and body-mass index with 120 of the 445 obese subjects without an MC4R mutation. All mutation carriers reported binge eating, as compared with 14.2 percent of obese subjects without mutations (P<0.001) and 0 percent of the normal-weight subjects without mutations. The prevalence of binge eating was similar among carriers of mutations in the leptin-binding domain of LEPR and noncarriers. No mutations were found in the region of POMC encoding alpha melanocyte-stimulating hormone. CONCLUSIONS: Binge eating is a major phenotypic characteristic of subjects with a mutation in MC4R, a candidate gene for the control of eating behavior.

Adolescent↗

SNP analysis of the inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) gene by a fluorescence-adapted SSCP method.

BACKGROUND: Single-nucleotide polymorphisms (SNPs) are considered to be useful polymorphic markers for genetic studies of polygenic traits. Single-stranded conformational polymorphism (SSCP) analysis has been widely applied to detect SNPs, including point mutations in cancer and congenital diseases. In this study, we describe an application of the fluorescent labeling of PCR fragments using a fluorescent-adapted primer for SSCP analysis as a novel method. METHODS: Single-nucleotide polymorphisms (SNPs) of the inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP) gene were analyzed using a fluorescence-adapted SSCP method. The method was constructed from two procedures: 1) a fluorescent labeling reaction of PCR fragments using fluorescence-adapted primers in a single tube, and 2) electrophoresis on a non-denaturing polyacrylamide gel. RESULTS: This method was more economical and convenient than the single-stranded conformational polymorphism (SSCP) methods previously reported in the detection of the labeled fragments obtained. In this study, eight SNPs of the IHRP gene were detected by the fluorescence-adapted SSCP. One of the SNPs was a new SNP resulting in an amino acid substitution, while the other SNPs have already been reported in the public databases. Six SNPs of the IHRP were associated with two haplotypes. CONCLUSIONS: The fluorescence-adapted SSCP was useful for detecting and genotyping SNPs.

Journal Article↗

Type 2 diabetes mellitus: from genes to disease.

The development of type 2 diabetes (T2DM) is determined by two factors: genetics and environment. The genetic background of T2DM is undoubtedly heterogeneous. Most patients with T2DM exhibit two different defects: the impairment of insulin secretion and decreased insulin sensitivity. This means that there are at least two pathophysiological pathways and at least two groups of genes that may be involved in the pathogenesis of T2DM. As far as genetic background [corrected] of T2DM is concerned, the disease may be divided into two large groups: monogenic and polygenic forms. In this review, we present genes known to cause rare monogenic forms of diabetes with predominant insulin deficiency (MODY - maturity-onset diabetes of the young, MIDD - maternally inherited diabetes with deafness) and uncommon syndromes of severe insulin resistance. We also describe some of the main approaches used to identify genes involved in the more common forms of T2D and the reasons for the lack of spectacular success in this field. Although major genes for T2DM still await to be discovered, we have probably established a "road map" that we should follow.

Deafness↗

Assessment of locomotor activity, acoustic and tactile startle, and prepulse inhibition of startle in inbred mouse strains and F1 hybrids: implications of genetic background for single gene and quantitative trait loci analyses.

As the use of transgenic and null mutation techniques in the development of animal models of disorders increases, the importance of selecting the appropriate genetic background also increases. The genetic background of the mouse strains used as models for various disorders is critical because of the potential for epistatic effects on the expression of transgenes and null mutations. Twelve strains of inbred mice and seven F1 hybrids were tested in multiple behavioural tasks including open-field locomotor activity, Y-maze activity, auditory and tactile startle and prepulse inhibition of startle response. Differences across genotypes were found for all variables measured. The range of variability among genotypes was dependent on the specific measure so careful consideration must be made in selecting a strain for testing a particular behaviour. Because of the polygenic nature of each of the behavioural phenotypes, the impact of a single gene manipulation may vary depending on the genetic background on which it is expressed. Moreover, quantitative trait loci methods could be applied to these behaviours.

Acoustic Stimulation↗

Association of estrogen receptor 1 intron 1 C/T polymorphism in Korean vitiligo patients.

BACKGROUND: Vitiligo is a common disease characterized by cutaneous white maculae due to loss of melanocytes. It is a polygenic disease, however, the exact pathogenesis of vitiligo is not yet known. The estrogen receptor (ESR) 1 gene was selected as a candidate gene because some researchers treated vitiligo successfully with the steroid-thyroid hormone mixture containing estrogen. Furthermore ESR was expressed in the melanocytes which have an important role in the pigmentation. The polymorphisms of ESR1 gene in vitiligo patients was not reported yet. OBJECTIVE: To determine whether polymorphisms of ESR1 gene were associated with susceptibility to vitiligo patients in Korean population. METHODS: We conducted case-control association study of vitiligo patients (120) and healthy controls (254). Genotypes of ESR1 gene (intron 1 C/T, exon 4 C/G, and exon 8 A/G) were determined by polymerase chain reaction followed by restriction enzyme digestion. RESULTS: Intron 1 T/C allele frequency was significantly different between patients and controls (P = 0.034). Intron 1 T/C genotype distribution (P = 0.021) and allele frequency (P = 0.013) were different between female vitiligo patients and female controls. Intron 1 T/C allele frequency showed significantly difference between generalized type of vitiligo patients and controls (P = 0.044). Genotype distributions and allele frequencies of exon 4 C/G and exon 8 A/G polymorphisms were not different between patients and controls. CONCLUSION: The present study suggests that ESR1 may be a possible risk factor for female or generalized type of vitiligo patients.

Adolescent↗

Cervico-oculo-Acoustic syndrome in a male with consanguineous parents.

BACKGROUND: The cervico-oculo-acoustic syndrome comprises Klippel-Feil anomaly, sensorineural deafness and Duane's retraction syndrome. Polygenic, autosomal dominant, and X-linked inheritance have been hypothesized. The disorder has rarely been reported in males. CASE REPORT: A 42-year-old male, born of consanguineous parents, presented with Duane's syndrome, mixed hearing loss, C2-C3 fusion, neck stiffness, and right facial palsy. A variety of cardiac, neurological and urogenital anomalies occurred in his relatives. The electro-oculographic studies showed impaired abduction and adduction of the right eye and impaired abduction of the left eye. Vergence, vertical eye movements and peripheral vestibular responses were normal. Somatosensory evoked potentials showed absence of the N13 peak and brainstem auditory evoked potentials bilateral delay of the I-III interpeak latencies. CONCLUSIONS: Consanguinity of the patient's parents, not previously reported, suggests autosomal recessive inheritance, but autosomal dominant inheritance is indicated by the family history. The pattern of the oculomotor deficit is consistent with bilateral dysplasia of the abducens nuclei with preserved internuclear neurons in the right abducens nucleus. Neurophysiological investigations revealed lower brainstem and cervical cord involvement.

Abducens Nerve↗