Malcolm N. Blumenthal

Variation in the Interleukin 4–Receptor α Gene Confers Susceptibility to Asthma and Atopy in Ethnically Diverse Populations

After a genomewide screen in the Hutterites was completed, the IL4RA gene was examined as the 16p-linked susceptibility locus for asthma and atopy. Seven known variants and one novel variant, representing all nonsynonymous substitutions in the mature protein, were examined in the Hutterites; on the basis of studies in the Hutterites, outbred white, black, and Hispanic families were genotyped for selected markers. All population samples showed evidence of association to atopy or to asthma (P values.039-.0044 for atopy and. 029-.0000061 for asthma), but the alleles or haplotypes showing the strongest evidence differed between the groups. Overall, these data suggest that the IL4RA gene is an atopy- and asthma-susceptibility locus but that variation outside the coding region of the gene influences susceptibility.

Genomewide Screen and Identification of Gene-Gene Interactions for Asthma-Susceptibility Loci in Three U.S. Populations: Collaborative Study on the Genetics of Asthma

The genomewide screen to search for asthma-susceptibility loci, in the Collaborative Study on the Genetics of Asthma (CSGA), has been conducted in two stages and includes 266 families (199 nuclear and 67 extended pedigrees) from three U.S. populations: African American, European American, and Hispanic. Evidence for linkage with the asthma phenotype was observed for multiple chromosomal regions, through use of several analytical approaches that facilitated the identification of multiple disease loci. Ethnicity-specific analyses, which allowed for different frequencies of asthma-susceptibility genes in each ethnic population, provided the strongest evidence for linkage at 6p21 in the European American population, at 11q21 in the African American population, and at 1p32 in the Hispanic population. Both the conditional analysis and the affected-sib-pair two-locus analysis provided further evidence for linkage, at 5q31, 8p23, 12q22, and 15q13. Several of these regions have been observed in other genomewide screens and linkage or association studies, for asthma and related phenotypes. These results were used to develop a conceptual model to delineate asthma-susceptibility loci and their genetic interactions, which provides a promising basis for initiation of fine-mapping studies and, ultimately, for gene identification.

Genetic Mapping of Ir Locus in Man: Linkage to Second Locus of HL-A

Fifty-seven members of a family that spanned three generations were studied for antigen E and ragweed skin sensitivity and HL-A antigens. There was significant association between the haplotype HL-A 2-12 and antigen E skin hypersensitivity (F = .22 to .26) in this family. The map order is first locus of HL-A, second locus of HL-A, and IrE. These determinants are considered to be part of the linkage group HL-1.

Clinical evaluation of ketorolac tromethamine 0.5% ophthalmic solution for the treatment of seasonal allergic conjunctivitis

We evaluated 148 patients with allergic conjunctivitis in a double-masked, paired comparison clinical trial comparing ketorolac 0.5% ophthalmic solution with vehicle. Patients received one drop of each study medication in preassigned eyes, four times a day, for seven days. Both treatments showed significant changes from baseline in the signs and symptoms associated with allergic conjunctivitis. Evaluations at the final visit (day 7 or 8) showed that ketorolac-treated eyes had a significant treatment response when compared to vehicle-treated eyes for conjunctival inflammation (p = 0.010), ocular itching (p = 0.006), swollen eyes (p = 0.002), discharge/tearing (p = 0.021), foreign body sensation (p = 0.035), and conjunctival injection (p = 0.016). Mean scores evaluating the overall therapeutic effect of the study treatments at the completion of the study were higher for ketorolac-treated eyes than for vehicle-treated eyes as rated by investigators (p = 0.004) and study patients (p < 0.001). Results of this study confirmed the trends of a previous study showing that ketorolac 0.5% ophthalmic solution applied topically is an effective therapy for allergic conjunctivitis.

Genetic analysis of atopy in three large kindreds : no evidence of linkage to D11S97

Both genetic and environmental influences have been implicated in the pathogenesis of atopic disease. A recent report suggested that a major gene providing susceptibility to atopy was transmitted in a pattern consistent with autosomal dominant inheritance and evidence was presented that places the disease locus near the D11S97 marker on human chromosome 11q. In this report, we present three large, highly characterized pedigrees in which atopy is transmitted in a pattern consistent with autosomal dominant inheritance. Genotypes at the D11S97and HLA loci were evaluated using both lod score and sib pair methods of analysis. In these pedigrees, we reject close to moderate linkage (up to 10 cM) of atopy with both D11S97 and HLA.

A genome-wide search for allergic response (atopy) genes in three ethnic groups: Collaborative Study on the Genetics of Asthma

Atopy is an IgE-mediated condition known to aggregate in families and is a major risk factor for asthma. As part of the Collaborative Study on the Genetics of Asthma (CSGA), a genome-wide scan for atopy, defined by skin sensitivity to one or more common environmental allergens, was conducted in 287 CSGA families (115 African American, 138 Caucasian and 34 Hispanic). Using a nonparametric genetic analysis approach, two regions were observed in the sample of all families that yielded multipoint lod scores >1.5 (chromosome 11q, lod=1.55 between D11S1986 and D11S1998; chromosome 20p between D20S473 and D20S604, lod=1.54). Modeling that included multiple genomic positions simultaneously indicated that four chromosomal regions accounted for the majority of evidence for linkage in the combined families. These four regions are on chromosomes 10p near D10S1412 (lod=0.94), 11q near D11S1986 (lod=1.76), 17q near D17S784 (lod=0.97) and 20p near D20S473 (lod=1.74). In the subset of pedigrees giving positive evidence for linkage on chromosome 11q, the evidence for linkage increased by lod scores greater than one in four other chromosomal regions: 5q (D5S1480, lod=1.65), 8p (D8S1113, lod=1.60), 12p (D12S372, lod=1.54) and 14q (D14S749, lod=1.70). These results suggest that several regions may harbor genes contributing to the risk for atopy and these may interact with one another in a complex manner.

Fluticasone propionate aqueous nasal spray compared with terfenadine tablets in the treatment of seasonal allergic rhinitis

BACKGROUND Comparative studies with topical corticosteroids and antihistamines for treatment of allergic rhinitis have not always demonstrated clear distinctions between the two on the basis of therapeutic efficacy. OBJECTIVE This study was designed to compare the efficacy and tolerability of fluticasone propionate aqueous nasal spray with those of terfenadine in the treatment of seasonal allergic rhinitis. METHODS Three hundred forty-eight patients with allergic rhinitis were given fluticasone propionate aqueous nasal spray (200 micrograms once daily), terfenadine tablets (60 mg twice daily), or placebo for 4 weeks in a multicenter, randomized, double-blind, double-dummy, parallel-group study. RESULTS Clinician-rated total nasal symptom scores after 1, 2, 3, and 4 weeks of therapy and patient-rated total nasal symptom scores throughout treatment were significantly (p <0.05) lower in the fluticasone propionate group compared with the terfenadine group or the placebo group. Terfenadine was not statistically different from placebo on the basis of clinician-related nasal symptom scores, except for sneezing. Total nasal airflow, measured by rhinomanometry, significantly (p <0.05) improved in the fluticasone propionate group compared with the terfenadine group or the placebo group. More fluticasone propionate-treated patients compared with placebo-treated patients had reduced nasal mucosal eosinophil counts after 4 weeks of therapy (p <0.05). No serious or unusual drug-related adverse events were reported. Morning plasma cortisol concentrations after 4 weeks of therapy did not differ among groups. CONCLUSION Fluticasone propionate aqueous nasal spray is more effective than terfenadine tablets for treatment of seasonal allergic rhinitis.

Antistaphylococcal IgE in patients with atopic dermatitis

Levels of IgE antibodies to Staphylococcus aureus and Staphylococcus epidermidis were determined in eleven patients with typical atopic dermatitis, with no history of furuncles or severe staphylococcal infection. Increased IgE binding to S. aureus but not to S. epidermidis was observed. Fifteen patients with hyperimmunoglobulinemia E-staphylococcal abscess syndrome had increased IgE binding not only to S. aureus but also to S. epidermidis. Other control groups of patients with elevated IgE levels or recurrent staphylococcal infection had normal IgE binding activity to both strains of staphylococci. Interaction of staphylococcal antigens from bacteria on skin with antistaphylococcal IgE antibodies on mast cells could induce mast cell release, evoke itch, and aggravate atopic dermatitis.

Efficacy and Safety of Nedocromil Sodium Ophthalmic Solution in the Treatment of Seasonal Allergic Conjunctivitis

To assess the efficacy and safety of twice-daily administration of nedocromil sodium 2% ophthalmic solution, we performed a multicenter study involving 140 patients with seasonal allergic conjunctivitis. Subjects had a history of seasonal allergic conjunctivitis and positive results of a skin test to ragweed. The trial coincided with the peak ragweed pollen season at five treatment centers. Patients treated with nedocromil sodium had improvements in symptoms with statistically significant reductions recorded for eye itching (P less than or equal to .04), conjunctival injection (P less than or equal to .001), and overall disease severity (P less than or equal to .001) as compared to the placebo-treated group. Adverse events were minor and transient. We concluded that nedocromil sodium 2% ophthalmic solution administered twice daily is effective in relieving major symptoms associated with seasonal allergic conjunctivitis.

A coding polymorphism in the CYSLT2 receptor with reduced affinity to LTD4 is associated with asthma

BACKGROUND Cysteinyl leukotrienes (CYSLTR) are potent biological mediators in the pathophysiology of asthma for which two receptors have been characterized, CYSLTR1 and CYSLTR2. The leukotriene modifying agents currently used to control bronchoconstriction and inflammation in asthmatic patients are CYSLTR1-specific leukotriene receptor antagonists. In this report, we investigated a possible role for therapeutic modulation of CYSLTR2 in asthma by investigating genetic association with asthma and further characterization of the pharmacology of a coding polymorphism. METHODS The association of CYSLTR2 polymorphisms with asthma was assessed by transmission disequilibrium test in two family-based collections (359 families from Denmark and Minnesota, USA and 384 families from the Genetics of Asthma International Network). RESULTS A significant association of the coding polymorphism, 601A>G, with asthma was observed (P = 0.003). We replicated these findings in a collection of 384 families from the Genetics of Asthma International Network (P = 0.04). The G allele is significantly under-transmitted to asthmatics, indicating a possible role for this receptor in resistance to asthma. The potency of cysteinyl leukotrienes at the wild-type CYSLTR2 and the coding polymorphism 601A>G were assessed using a calcium mobilization assay. The potency of LTC4 and LTE4 was similar for both forms of the receptor and LTB4 was inactive, however, LTD4 was approximately five-fold less potent on 601A>G compared to wild-type CYSLTR2. CONCLUSIONS Since 601A>G alters the potency of LTD4 and this variant allele may be associated with resistance to asthma, it is possible that modulation of the CYSLTR2 may be useful in asthma pharmacotherapy.