Skin test results in related and unrelated persons with allergic rhinitis.
BACKGROUND
First degree relatives of patients with allergic rhinitis are at increased risk of having the disorder. It is not yet clear whether or not two such related persons with allergic rhinitis are more likely to be skin test positive to the same specific allergic extracts than unrelated persons with allergic rhinitis.


OBJECTIVE
To determine whether or not first degree relatives (parent and child or full siblings) with allergic rhinitis are more likely to be skin test positive to the same allergen extracts than unrelated persons with the disease.


METHODS
A retrospective chart review of Allergy Clinic patients was performed. Skin test results for 12 common aeroallergen extracts were compared in 32 pairs of genetically related subjects and 32 pairs of age-matched and sex-matched unrelated subjects, all with allergic rhinitis. The percent of concordant results (both members of a pair skin test positive or both negative) and discordant results (one member of a pair positive and the other negative) were calculated and compared for related and unrelated groups. Also, the expected rates of positive concordance (both skin tests positive) based on the prevalence of skin test positively in the two groups were calculated and compared with the corresponding observed rates.


RESULTS
Results were concordant in 242 of 384 skin tests (63%) in related pairs versus 233 of 384 skin tests (61%) in unrelated pairs (P = .28, not significant). The expected and observed rates of positive concordance were not significantly different in the related (P = .38) or unrelated (P = .49) groups. When the groups were subdivided into parent-child pairs and sibling pairs, a similar lack of significant differences between the groups was found.


CONCLUSIONS
It is concluded that first degree relatives, both with allergic rhinitis, are no more likely to be skin test positive to the same allergen extracts than unrelated persons with this disease. Further, it seems appropriate to advise patients with allergic rhinitis that their first degree relatives who also have the disorder will not necessarily have the same specific allergies.
Kelso
J M
JM
Department of Internal Medicine, Allergy Division, Naval Medical Center, San Diego, California, USA.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009679:Nuclear Family; D010287:Parent-Child Relations; D012189:Retrospective Studies; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology / Q000235:genetics*; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology / Q000235:genetics*; D012882:Skin Tests