Atopy (Greek ατοπία - placelessness, not allocatable) or atopic syndrome is the clustering of eczema (atopic dermatitis), allergic conjunctivitis, allergic rhinitis and asthma in certain individuals. There appears to be a strong hereditary component, presumably certain genes coding proteins involved in the normal immune response mechanism i.e Human leukocyte antigen, although environmental factors have also been implicated.
The individual components are all caused at least in part by allergy (type I hypersensitivity reactions). These responses appear in the contact after the body was exposed to different allergens, for example specific kinds of food, pollen, dander and insect venoms. Although atopy has various definitions, most consistently it is defined by the presence of elevated levels of total and allergen-specific IgE in the serum of patient, leading to positive skin-prick tests to common allergens.
Some physical attributes have been associated with atopic syndrome, although the real relationship is poorly understood:
- A skin fold under the eyes termed "Dennie-Morgan folds";
- A collection of short hairs under the bangs (American English), or fringe (British English);
- It is more common in redheads (American English), or ginger-haired people (British English).
- Cracks in the skin under the earlobe
- In elbow flexures and/or hollow of the knees
- Nipple eczema
- Subtype Dyshidrosis
- Keratosis pilaris
- Chronic or seasonal rhinitis
Association analysis of common variants of STAT6, GATA3, and STAT4 to asthma and high serum IgE phenotypes.
J Allergy Clin Immunol. 2005 Jan;115(1):80-7. Pykalainen M, Kinos R, Valkonen S, Rydman P, Kilpelainen M, Laitinen LA, Karjalainen J, Nieminen M, Hurme M, Kere J, Laitinen T, Lahesmaa R.
- BACKGROUND: Immune responses characterized by T H 2 type cells and IgE are important for the development of asthma and atopy. The transcription factors STAT6, GATA3, and STAT4 mediate the cytokine-induced development of naive CD4 + T cells into either T H 1 or T H 2 type. OBJECTIVE: We studied genetic variation of the STAT6, GATA3, and STAT4 genes and examined whether single nucleotide polymorphisms (SNPs) in these loci were associated with asthma or serum high IgE levels in the Finnish asthmatic families. METHODS: With denaturing high-performance liquid chromatography we screened all exons and exon-intron boundaries of the genes in 14 to 22 patients. All identified SNPs were genotyped in 120 nuclear families, and the haplotypes were analyzed by Haplotype Pattern Mining based statistical analysis. When potential association was observed, the analysis was replicated among 245 asthmatic patients and 405 population-based control subjects. RESULTS: A total of 23 SNPs were identified, of which 8 were not previously listed in the SNP database. Interestingly, a haplotype analysis of GATA3 showed 3 related haplotypes that associated with different asthma and atopy related phenotypes among both the family and case-control data sets. For STAT6 and STAT4, no significant association to asthma or serum total IgE levels was observed. CONCLUSIONS: We identified a panel of novel SNPs in genes coding for proteins important in the T H 1/T H 2 cell differentiation. SNPs of the GATA3 gene showed an initial association to asthma-related phenotypes. Elucidation of the importance of the identified panel of SNPs in other T H 1/T H 2 mediated diseases will be of great interest.