When we defined atopy as the presence of a positive skinprick test (greater-than-or-equal-to 2 mm) to any of a panel of common allergens, a higher than normal concentration of total serum IgE, or a positive radioallergosorbent test for a specific IgE, we found that 125 (62%) of the sibling-pairs affected by atopy shared the maternal 11q13 allele and 78 (38%) did not. This distribution differs significantly from the expected 50/50 distribution (p=0.001). Of paternally derived alleles, 83 (46%) were shared and 96 (54%) were not (not significantly different from 50/50). The result was similar whatever definition of atopy was used and with other genetic markers on 11q.

These findings show that transmission of atopy at the chromosome 11q locus is detectable only through the maternal line. The pattern of inheritance is consistent either with paternal genomic imprinting or with maternal modification of developing immune responses.