Mutations in the gene encoding for the beta 2-adrenergic receptor in normal and asthmatic subjects.
It has long been hypothesized that a defective beta 2-adrenergic receptor (beta 2AR) may be a pathogenic factor in bronchial asthma. We examined the gene encoding the beta 2AR to assess the frequency of polymorphisms in 51 patients with moderate to severe asthma and 56 normal subjects. Nine different point mutations were found in both heterozygous and homozygous forms at nucleic acid residues 46, 79, 100, 252, 491, 523, 1053, 1098, and 1239. No mutations resulting in large deletions or frame shifts were detected. Of these nine polymorphisms, four were found to cause changes in the encoded amino acids at residues 16, 27, 34, and 164. The most frequent polymorphisms were arginine 16 to glycine (Arg16-->Gly) and glutamine 27 to glutamic acid (Gln27-->Glu). The other two polymorphisms, valine 34 to methionine, and threonine 164 to isoleucine, occurred in only four subjects. The incidence of beta 2AR homozygous polymorphisms was no greater in asthmatic patients as compared with controls (Arg16-->Gly: 53% versus 59%, Gln27-->Glu: 24% versus 29%, respectively; P = NS). Some subjects were found to have both of these polymorphisms simultaneously, but there was no difference in incidence between the two groups, with 23% of asthmatics and 28% of normal subjects being homozygous for both polymorphisms. The apparently normal subjects with both polymorphisms did not have subclinical hyperreactive airways disease as determined by methacholine challenge testing. In the asthma group, one mutation (Arg16-->Gly) identified a subset of patients with a distinct clinical profile.(ABSTRACT TRUNCATED AT 250 WORDS)
Reihsaus
E
E
Department of Medicine (Pulmonary), University of Cincinnati College of Medicine, Ohio.
Innis
M
M
MacIntyre
N
N
Liggett
S B
SB
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001249:Asthma / Q000097:blood / Q000235:genetics / Q000503:physiopathology*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D006580:Genetic Carrier Screening; D006801:Humans; D016210:Methacholine Chloride; D008875:Middle Aged; D008961:Models, Structural; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D011943:Receptors, Adrenergic, beta / Q000737:chemistry / Q000235:genetics*; D012016:Reference Values
D011943:Receptors, Adrenergic, beta; D016210:Methacholine Chloride