Peljto AL et al. – While systemic sclerosis (SSc)–associated IP is clinically, radiologically, and histologically similar to other forms of interstitial pneumonia (IP), it appears to have distinct genetic risk factors. This study highlights the genetic and phenotypic heterogeneity of IP in general.Methods
- The authors examined the minor allele frequency of the MUC5B polymorphism among 231 subjects with SSc, 109 with IP and 122 without IP.
- IP diagnosis was confirmed by HRCT imaging and defined as presence of reticular infiltrates and/or honeycomb cysts.
- Forced vital capacity (FVC) and diffusing capacity (DLCO) were also assessed.
- They found no association between IP and the MUC5B polymorphism among SSc subjects (OR=1.2, p–value=0.80).
- The frequencies of the MUC5B polymorphism among SSc subjects with IP (10.6%) and without IP (9.4%) were similar to the frequency observed in a population of unaffected controls (9.0%).
- In secondary analyses, they found the MUC5B polymorphism was not significantly associated with either FVC (p–value=0.42) or DLCO (p–value=0.06).
- No association with SSc–associated IP was found even when they used a more conservative definition of IP (FVC≤70% and evidence of reticulations or honeycombing vs. SSc FVC>70% and no evidence of reticulation or honeycombing).