METHODS: A PubMed search for relevant published articles was conducted using the following search terms singly or in combination: "atopy," "atopic disease," "atopic disorder," "International Study of Asthma and Allergies in Childhood," "ISAAC," "asthma," "allergic rhinitis," "eczema," and "food allergy" in combination with the names of countries of the Arabian Peninsula (Kuwait, United Arab Emirates, Bahrain, Qatar, Oman, Kingdom of Saudi Arabia, and Yemen). The search captured studies published up to December 2017.
RESULTS: A total of 8 publications reporting prevalence rates of any type of atopic disease in children in 7 countries of the Arabian Peninsula were retrieved. The prevalence of all atopic disorders was comparable between countries of the Arabian Peninsula. The overall prevalence of asthma ranged from 8 to 23%, while the reported prevalence of eczema ranged from 7.5 to 22.5%. There was great variation in the prevalence rates of rhinoconjunctivitis, which ranged from 6.3 to 30.5%. The prevalence of food allergy (8.1%) was reported for 1 country only, the United Arab Emirates.
CONCLUSIONS: The reported overall rates of atopic disease in countries of the Arabian Peninsula are comparable to those reported in other industrialized countries. This is probably related to the good economic status in the region, which is reflected in the living standards and lifestyle. Further, genetic factors, such as factors related to gene polymorphism, and the high rate of consanguinity in the region may contribute to the higher prevalence of atopic diseases.
OBJECTIVE: To determine whether genetic variants in and around SPINK5 are associated with IgE-mediated food allergy.
METHOD: We genotyped 71 "tag" single nucleotide polymorphisms (tag-SNPs) within a region spanning ~263 kb including SPINK5 (~61 kb) in n=722 (n=367 food-allergic, n=199 food-sensitized-tolerant and n=156 non-food-allergic controls) 12-month-old infants (discovery sample) phenotyped for food allergy with the gold standard oral food challenge. Transepidermal water loss (TEWL) measures were collected at 12 months from a subset (n=150) of these individuals. SNPs were tested for association with food allergy using the Cochran-Mantel-Haenszel test adjusting for ancestry strata. Association analyses were replicated in an independent sample group derived from four paediatric cohorts, total n=533 (n=203 food-allergic, n=330 non-food-allergic), mean age 2.5 years, with food allergy defined by either clinical history of reactivity, 95% positive predictive value (PPV) or challenge, corrected for ancestry by principal components.
RESULTS: SPINK5 variant rs9325071 (A⟶G) was associated with challenge-proven food allergy in the discovery sample (P=.001, OR=2.95, CI=1.49-5.83). This association was further supported by replication (P=.007, OR=1.58, CI=1.13-2.20) and by meta-analysis (P=.0004, OR=1.65). Variant rs9325071 is associated with decreased SPINK5 gene expression in the skin in publicly available genotype-tissue expression data, and we generated preliminary evidence for association of this SNP with elevated TEWL also.
CONCLUSIONS: We report, for the first time, association between SPINK5 variant rs9325071 and challenge-proven IgE-mediated food allergy.
METHODS: A cross-sectional study was performed in 150 children aged 12-36 months.
EXCLUSION CRITERIA: recurrent infections, moderate to severe asthma, recent systemic steroid, other diseases affecting growth/nutrition. Growth parameters, SCORing Atopic Dermatitis (SCORAD), hemoglobin, hematocrit, sodium, potassium, albumin, protein, calcium, phosphate, B12, iron, and folate values were determined. Parents completed a 3-day food diary.
RESULTS: The prevalence of food restriction was 60.7%. Commonly restricted foods were shellfish 62.7%, nuts 53.3%, egg 50%, dairy 29.3%, and cow's milk 28.7%. Food-restricted children have significantly lower calorie, protein, fat, riboflavin, vitamin B12, calcium, phosphorus and iron intakes and lower serum iron, protein and albumin values. Z scores of weight-for-age (-1.38 ± 1.02 vs -0.59 ± 0.96, P = .00), height-for-age (-1.34 ± 1.36 vs -0.51 ± 1.22, P = .00), head circumference-for-age (-1.37 ± 0.90 vs -0.90 ± 0.81, P = .00), mid-upper arm circumference (MUAC)-for-age (-0.71 ± 0.90 vs -0.22 ± 0.88, P = .00), and BMI-for-age (-0.79 ± 1.15 vs -0.42 ± 0.99, P = .04) were significantly lower in food-restricted compared to non-food-restricted children. More food-restricted children were stunted, underweight with lower head circumference and MUAC. Severe disease was an independent risk factor for food restriction with OR 5.352; 95% CI, 2.26-12.68.
CONCLUSION: Food restriction is common in children with AD. It is associated with lower Z scores for weight, height, head circumference, MUAC, and BMI. Severe disease is an independent risk factor for food restriction.