A genetic variation in inositol polyphosphate 4 phosphatase A enhances susceptibility to asthma

Mamta Sharma, Jyotsna Batra, Ulaganathan Mabalirajan, Shilpy Sharma, Rana Nagarkatti, Jyotirmoi Aich, Surendra K. Sharma, Pramod V. Niphadkar, Balaram Ghosh*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Rationale:
Microarray data from mouse studies have identified a number of genes to be differentially expressed in allergen-sensitized mice lungs.

Objectives:
Taking leads from these datasets, we attempted to identify novel genes associated with atopic asthma in humans.

Methods:
We performed family-based genetic association analysis on selected markers within or in proximity of 21 human homologs of genes short-listed from ovalbumin-sensitized mouse studies in the Gene Expression Omnibus database of the National Center for Biotechnology Information. Family-based and case-control studies were undertaken for fine mapping and functional variation analysis of INPP4A (inositol polyphosphate 4 phosphatase type I). Western blot analysis was performed to analyze INPP4A protein stability from human platelets.

Measurements and Main Results:
Our genetic association studies of 21 human genes in 171 trios led to the identification of a biallelic repeat (rs3217304) in INPP4A, associated with atopic asthma (P = 0.009). Further studies using additional three single nucleotide polymorphisms (SNPs), +92031A/T, +92344C/T, and +131237C/T, and two microsatellite markers, D2S2311 and D2S2187, revealed significant genetic associations with loci +92031A/T(P = 0.0012)and +92344C/T (P = 0.004). A nonsynonymous SNP, +110832A/G(Thr/Ala), present within a sequence enriched with proline, glutamic acid, serine, and threonine (PEST), in proximity of these two loci, showed a significant association with atopic asthma (P = 0.0006). The association results were also replicated in an independent cohort of 288 patients and 293 control subjects (P = 0.004). PEST score and Western blot analyses indicated a functional role of this SNP in regulating INPP4A protein stability.

Conclusions:
In our study, INPP4A was identified as a novel asthma candidate gene, whereby the +110832A/G (Thr/Ala) variant affected its stability and was significantly associated with asthma.
Original languageEnglish
Pages (from-to)712-719
Number of pages8
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume177
Issue number7
DOIs
Publication statusPublished - Apr 2008
Externally publishedYes

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