Thursday, 24 January 2013

Genetic Susceptibility to ABPA in Cystic Fibrosis

What causes susceptibility of certain individuals to infection by aspergillus is largely unknown, Infections such as allergic bronchopulmonary aspergillosis (ABPA) and chronic pulmonary aspergillosis (CPA) are known to infect significant numbers of people (estimated at 5 million ABPA worldwide, 400 000 CPA) but infection in sufferers of cystic fibrosis are proportionally higher with up to 10% of all CF patients infected.

Genetics are thought to play a part in susceptibility both for those with and without CF, but clearly having CF is a major risk factor for ABPA. Nonetheless 90% of those with CF do not get ABPA so there are presumably further risk factors to take in for account.

We know the following (quoted from Cystic Fibrosis Foundation):
ABPA is more common in males and adolescents. It is also common in people who:
  • Have decreased lung function
  • Wheeze
  • Have allergies
  • Have asthma
  • Are positive for Pseudomonas species

These may act as clues - perhaps indicators of ABPA but also possible indicators of a genetic susceptibility to ABPA in some CF patients.

This paper suggest that there are particular genes associated with ABPA in CF patients which occur more frequently in those with the particular gene variant than those without. Quoting the conclusion in the paper:

a correlation exists between HLA-DRB1*15:01, -DRB1*11:04, DRB1*11:01, -DRB1*04 and -DRB1*07:01 alleles, and ABPA-CF susceptibility and suggest that HLA-DQB1*02:01 is an ABPA-CF resistance allele.
This means that CF patients could be screened for the presence of the ABPA resistance gene variant and if found appropriate prophylactic action could be taken. This could help minimise the occurence of ABPA in CF patients which would be a big step forward in improving management of that disorder.

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