Confirmed beta16 Arg/Arg polymorphism in a patient with uncontrolled asthma.
OBJECTIVE
To report a case of confirmed beta(16) Arg/Arg polymorphism (Arg/Arg) in a patient with uncontrolled asthma.


METHODS
A 49-year-old black female presented to the emergency department with acute shortness of breath with subsequent intubation. After extubation, she reported multiple hospitalizations for asthma with one prior intubation, adherence to asthma medications, and very frequent use of her short-acting beta(2)-agonist (SABA). Because of her asthma history, self-reported adherence, and race, she was tested for beta(2)-adrenoreceptor genotype, which revealed Arg/Arg. Based on these findings, beta(2)-agonists were discontinued and tiotropium (maintenance) and ipratropium (primary rescue) were initiated as part of her asthma regimen. Application of the Naranjo probability scale revealed probable causality between uncontrolled asthma in our patient and SABA use. The patient is followed in our outpatient pulmonary clinic and, at time of writing, had not been admitted to our hospital for asthma-related events.


CONCLUSIONS
Approximately 15% of Americans with asthma are Arg/Arg, with an increased prevalence in black and Asian populations. It is hypothesized that changes in the degree of sensitivity or desensitization to the bronchodilator effect of beta(2)-agonists may occur in these individuals. Data exist, although they are conflicting, suggesting that inhaled beta(2)-agonists may worsen clinical outcomes. Trials have reported declines in peak expiratory flow rates plus increases in asthma symptoms and exacerbations when SABAs have been used regularly in patients with Arg/Arg. Studies evaluating long-acting beta(2)-agonists (LABAs) have inconsistent results. Preliminary data suggest that anticholinergics may serve as a beneficial primary rescue medication instead of beta(2)-agonists in patients with Arg/Arg.


CONCLUSIONS
Clinicians should be aware of factors (eg, race and polymorphisms) that may predict unfavorable outcomes with regular SABA and possibly LABA use. Patients with poor asthma control despite adherence to asthma therapy may benefit from beta(2)-adrenoreceptor genotyping and, possibly, from anticholinergics.
Metzger
Nicole L
NL
Virginia Commonwealth University Health System, Medical College of Virginia Hospitals, Richmond, VA 23298, USA.
Kockler
Denise R
DR
Gravatt
Leigh Anne Hylton
LA
D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D001249:Asthma / Q000188:drug therapy* / Q000235:genetics; D001993:Bronchodilator Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008875:Middle Aged; D011110:Polymorphism, Genetic; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics*; D012602:Scopolamine Derivatives / Q000627:therapeutic use; D000069447:Tiotropium Bromide
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D018343:Receptors, Adrenergic, beta-2; D012602:Scopolamine Derivatives; D001120:Arginine; D000069447:Tiotropium Bromide