Idiopathic pulmonary fibrosis (IPF) is a fatal, scarring, progressive and irreversible interstitial lung disease. When IPF occurs in more than one first-degree relative it is termed familial pulmonary fibrosis (FPF). Patients with connective tissue disease (CTD) can develop inflammation and scarring in their alveolar cells, which may progress to interstitial lung disease or pulmonary fibrosis. We compared the diagnostic yield of genomic testing when applied to IPF, FPF and CTD and catalogued the genetic landscape of pulmonary fibrosis mutations in Ireland. We recruited and consented approximately 115 patients to the study via the Respiratory and Rheumatology clinics at Beaumont Hospital, Dublin. To date, we have analysed sequence data from 61 patients; 13 with IPF, 12 with FPF and 36 with CTD-ILD. Whole-exome data was obtained from blood-derived DNA and processed using a GATK V4.2 bioinformatics pipeline. A diagnostic assessment of each variant was conducted according to the criteria of the American College of Medical Genetics and Genomics. We identified a pathogenic RTEL1 variant [NM_001283009:exon30:c.C2920T] in a family with FPF. We identified a variant of unknown significance in RTEL1[RTEL1:NM_001283009:exon14:c.C1189G:p.Q397E] in another family with FPF. No pathogenic/likely-pathogenic variants were identified in the IPF and CTD datasets, although we did identify variants of unknown significance in RTEL1, SFTPA1, NAF1 and ZCCHC8. These results indicate a diagnostic yield for FPF of 12.5% in the Irish population, although the sample size analysed to date is small. A lack of pathogenic variants in the IPF or CTD groups is consistent with the literature.