Population-based studies reveal differences in the allelic frequencies of two functionally significant human interleukin-4 receptor polymorphisms in several ethnic groups.
OBJECTIVE
The presence of functionally significant human interleukin-4 receptor sequence variants, Gln551Arg and Ile50Val, was examined in four anonymous New York State populations defined by ethnic origin. These variants were studied because they are associated with atopy or atopic asthma whose prevalence varies in different populations.


METHODS
PCR/RFLP (Ile50Val) and PCR/allele-specific oligonucleotide hybridization (Gln551Arg) assays were developed to detect both polymorphisms in 855 newborn screening specimens.


RESULTS
Arg551 was most frequently found in Blacks (allele frequency of 68%). However, the Ile50 allele was most common in Whites (allele frequency, 87%). Significantly more Blacks had chromosomes bearing both of the "enhanced signaling" variants (Ile50/Arg551).


CONCLUSIONS
Enhanced IL-4R signaling is associated with increased IgE production (atopy). Therefore, our data suggest that the African American population may be at increased risk for diseases, including asthma, which are associated with atopy. These data also emphasize the importance of determining the frequencies of single nucleotide polymorphisms in different populations before drawing conclusions from allele association studies, since the background allele frequencies may be disparate between different populations.
Laboratory of Molecular Genetic Epidemiology, New York State Department of Health, Wadsworth Center, Albany 12201-0509, USA.
M
M
Caggana
K
K
Walker
A A
AA
Reilly
J M
JM
Conroy
S
S
Duva
A C
AC
Walsh
D000483:Alleles; D001249:Asthma / Q000453:epidemiology / Q000208:ethnology; D044383:Black People; D004720:Endonucleases / Q000378:metabolism; D005787:Gene Frequency; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D019948:Receptors, Interleukin-4 / Q000235:genetics*; D044465:White People; D001741:Black or African American
D019948:Receptors, Interleukin-4; D007073:Immunoglobulin E; D004720:Endonucleases