[Genetic diagnosis of autosomal dominant polycystic kidney disease using multiplex-PCR]. / Diagnóstico genético de poliquistosis renal autosómica dominante mediante PCR múltiple.

BACKGROUND: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common life-threatening hereditary disease. Molecular analysis with highly polymorphic short tandem repeats, located in the vicinity of the two genes responsible for the disease (PKD1 and PKD2), is used to confirm diagnosis and give genetic counseling to members of affected families. METHODS: We have developed a new assay to genotype five PKD1 and four PKD2 markers, based on two multiplex PCR reactions, and capillary electrophoresis analysis. A total of 110 subjects, belonging to 14 affected families, were genotyped to confirm the concordance with the singleplex method used previously. RESULTS: The amplicons ranged from 95 to 154 bp in length, and complete STR profiles were obtained from 1-5 ng DNA. The specificity of the multiplex PCR system was 88,5% (95%CI= 75,9-95,2), and the sensitivity, 87,9 (95%CI= 76,1-94,6). CONCLUSIONS: This is a useful strategy that, together with automated computer-based allele detection, allows reliable, simple, faster, and cheaper genetic analysis than the previous singleplex method.

Assessment of the DQ heterodimer test in the diagnosis of celiac disease in the Canary Islands (Spain).

BACKGROUND: Celiac disease is a multifactorial disorder of the proximal small intestine associated with a permanent intolerance to gluten. The HLA-DQ(alpha1*0501, beta1*02) heterodimer is strongly associated with this disease. MATERIALS AND METHODS: The authors studied a sample of 354 unrelated Caucasoid individuals: 118 patients with celiac disease and 236 control subjects. All patients and controls subjects were born in Gran Canaria (Canary Islands) at least two generations ago. The authors typed the HLA-DQA1 and DQB1 genes by DNA methods. The positive and negative predictive values of the test were studied. RESULTS: The mean age at diagnosis was 25.4 months, with a statistically significant proportion of females (64.4%, P < 0.002). For DQB1 gene, the susceptibility allele found was DQB1*02 (relative risk [RR] = 7.60, confidence interval [CI]: 5.35-10.78), whereas for the DQA1 gene, the susceptibility alleles found were DQA1*0501 (RR = 2.99, CI: 2.16-4.14) and DQA1*0201 (RR = 1.88, CI: 1.25-2.82). The presence of the DQ(alpha1*0501, beta1*02) heterodimer was strongly associated with the disease (92.4% in the patients group vs. 21.6% in control subjects). HLA-DQ8 heterodimer was absent in the authors' patients. DQB1*02 homozygous subjects presented a higher relative risk for celiac disease. There was no correlation of DQB1*02 dosage with age at onset below 12 years of age or with gender distribution. Sensitivity, specificity, and the positive and negative predictive values of the test were 92.4%, 78.4%, 68.1%, and 95.4%, respectively. CONCLUSIONS: The presence of the DQ2 (DQA1*0501/DQB1*02) heterodimer is strongly associated with celiac disease in the population studied by the authors. The value of this test derives from its ability to exclude disease when a negative result occurs.

IL4-R1 (5q31-q33) and FcepsilonRI-betaca (11q13) markers and atopy: a case/control study in a spanish population.

BACKGROUND: Rhinoconjunctivitis and bronchial asthma are atopic diseases with a high prevalence in the Canary Islands (Spain). Given that the most prevalent allergen is the house-dust mite Dermatophagoides pteronyssinus, early detection of genetically susceptible subjects would allow the application of preventive measures. The objective was to investigate the possible association of IL4-R1 (chromosome 5q31-q33) and FcepsilonRI-betaca (chromosome 11q13) markers with the atopic disease in our population. METHODS: We performed a case/control study in which patients were recruited on the basis of diagnosis of rhinoconjunctivitis and/or bronchial asthma, and positive skin prick test to D. pteronyssinus. Analysis of IL4-R1 and FcepsilonRI-betaca microsatellites was carried out by PCR and electrophoresis in acrylamide gels. RESULTS: We have not found evidence of association between IL4-R1 and FcepsilonRI-betaca markers and atopic disease in our population. In addition, these markers have shown a high percentage of homozygosis. CONCLUSIONS: IL4-R1 and FcepsilonRI-betaca markers have not proved to be useful genetic markers for linkage or association studies in our population.

LTC4-synthase A-444C polymorphism: lack of association with NSAID-induced isolated periorbital angioedema in a Spanish population.

BACKGROUND: The mechanism of nonsteroidal anti-inflammatory drug (NSAID)-induced reactions is unknown. However, strong evidence supports the hypothesis of an enhanced production of cysteinyl-leukotrienes. The existence of a polymorphism (A-444C) in the promoter region of the leukotriene (LT)C4-synthase gene (the terminal enzyme in the LTC4 production pathway) has been reported. This polymorphism has yielded contradictory results on its association with aspirin-induced asthma. OBJECTIVE: The present study was designed to investigate the possible genetic association of C(-444) allele and a specific clinical phenotype of NSAID sensitivity, the NSAID-induced isolated periorbital angioedema, via a case/control study. METHODS: The polymorphism A-444C was analyzed in 58 patients with NSAID-induced periorbital angioedema and 61 control subjects, who had undergone single-blind, placebo-controlled oral challenge. Genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: We have not found an association of C(-444), allele with NSAID-induced isolated periorbital angioedema. CONCLUSIONS: Further studies are needed to determine whether polymorphisms in the LTC4-synthase gene or other leukotriene-forming enzymes are involved in the pathogenesis of the different subsets of NSAID sensitivity.

Pocket 4 in the HLA-DRB1 antigen-binding groove: an association with atopy.

BACKGROUND: Many studies have attempted to identify an association between HLA genes and atopy, given the role of HLA molecules in the regulation of the immune response. In the case of house-dust mites, it is difficult to find an association with a particular HLA allele, due to the complexity of the allergen. The objective was to investigate whether HLA-DRB1 functional groups are better correlated with the atopic disease in our population than DRB1 alleles. METHODS: The method was reanalysis of the HLA-DRB1 data of a previous case/ control study. RESULTS: The "Dr" group was found to be associated with the atopic disease in our population. CONCLUSIONS: Grouping HLA-DRB1 alleles into functional categories may assist in the search for predictive factors in relation to atopic disease.

Linkage of house dust mite allergy with the HLA region.

BACKGROUND: Atopy is a multifactorial disease, the pathogenesis of which is influenced by both genetic and environmental conditions. Genes in the HLA region have been involved in the control of the IgE response. OBJECTIVE: In order to investigate whether allergy to house dust mite is associated with HLA in our population, we performed sib-pair analysis in 18 families and a case/control study of 161 non-related individuals. METHODS: Levels of total and specific IgE were determined, skin-prick tests were carried out and clinical history was reviewed for every subject in the study. HLA class II typing was performed by the polymerase chain reaction with sequence specific primers. RESULTS: We observed a significant difference from expected values in haplotypes shared by affected sibs; however, the case/control study did not reveal any association with any particular allele. CONCLUSION: These results suggest that any particular HLA-DRB1/DQA1/DQB1 allele is responsible for the development of allergy to house dust mite in the Spanish population. Some other locus in or close to the HLA region might be involved, e.g., the tumour necrosis factor gene, a possibility that would explain the significant difference from expected values in the segregation of HLA haplotypes.