Summary BACKGROUND Lynch syndrome is caused by germline mutations in mismatch repair genes (MSH2, MLH1, MSH6 or PMS2), which lead to a high risk of predominantly colorectal and endometrial cancer. Recently, we found that also constitutional 3′ end deletions of EPCAM can cause Lynch syndrome through epigenetic silencing of MSH2 in EPCAM expressing tissues. This results in a tissue specific MSH2-deficiency, which may evoke a different cancer risk and spectrum. To optimize the care for EPCAM deletion carriers we studied their cancer risk and spectrum. METHODS Clinical data of 194 carriers from 41 EPCAM families were systematically collected and compared to those of 431 carriers from 91 families with mutations in MLH1, MSH2, or MSH6. FINDINGS EPCAM deletion carriers exhibited a 75% [95%CI 65–85%] cumulative risk of colorectal cancer before the age of 70 years, with a mean age at diagnosis of 43 years, which is comparable to that of carriers of a combined EPCAM-MSH2 deletion (69% [95%CI 47-91%], p=0·8609) or of a mutation in MSH2 (77% [95%CI 64-90%], p=0·5892) or MLH1 (79% [95%CI 68-90%], p=0·5492) and higher than that of MSH6 mutation carriers (50% [95%CI 38-62%], p<0·0001). In contrast, women with EPCAM deletions (n=87) exhibited a 12% [95%CI 0-27%] cumulative risk of endometrial cancer, which is significantly lower than in carriers of a combined EPCAM-MSH2 deletion (55% [95%CI 20-90%], p<0·0001) or of a mutation in MSH2 (51% [95%CI 33-69%], p=0·0006) or MSH6 (34% [95%CI 20-48%], p=0·0309) and lower than in MLH1 (33% [95%CI 15-51%] p=0·1193) mutation carriers. This risk seems to be restricted to large deletions that extend close to the MSH2 gene promoter. Overall, a relatively high incidence of duodenal (n=3) and pancreatic (n=4) cancers was observed. INTERPRETATION EPCAM deletion carriers do have a high risk of colorectal cancer. Only those with deletions extending close to the MSH2 promoter have an increased risk of endometrial cancer. These results underscore the impact of mosaic MSH2-deficiency on cancer risk and are indicative for a protocol revision for surveillance and preventive surgery in EPCAM deletion carriers.

Background:Birt–Hogg–Dubé (BHD) syndrome is an autosomal dominant condition caused by germline FLCN mutations, and characterised by fibrofolliculomas, pneumothorax and renal cancer. The renal cancer risk, cancer phenotype and pneumothorax risk of BHD have not yet been fully clarified. The main focus of this study was to assess the risk of renal cancer, the histological subtypes of renal tumours and the pneumothorax risk in BHD.Methods:In this study we present the clinical data of 115 FLCN mutation carriers from 35 BHD families.Results:Among 14 FLCN mutation carriers who developed renal cancer 7 were <50 years at onset and/or had multifocal/bilateral tumours. Five symptomatic patients developed metastatic disease. Two early-stage cases were diagnosed by surveillance. The majority of tumours showed characteristics of both eosinophilic variants of clear cell and chromophobe carcinoma. The estimated penetrance for renal cancer and pneumothorax was 16% (95% minimal confidence interval: 6–26%) and 29% (95% minimal confidence interval: 9–49%) at 70 years of age, respectively. The most frequent diagnosis in families without identified FLCN mutations was familial multiple discoid fibromas.Conclusion:We confirmed a high yield of FLCN mutations in clinically defined BHD families, we found a substantially increased lifetime risk of renal cancer of 16% for FLCN mutation carriers. The tumours were metastatic in 5 out of 14 patients and tumour histology was not specific for BHD. We found a pneumothorax risk of 29%. We discuss the implications of our findings for diagnosis and management of BHD.

BackgroundChildhood-onset pulmonary arterial hypertension (PAH) is rare and differs from adult-onset disease in clinical presentation, with often unexplained mental retardation and dysmorphic features (MR/DF). Mutations in the major PAH gene, BMPR2, were reported to cause PAH in only 10–16% of childhood-onset patients. We aimed to identify more genes associated with childhood-onset PAH.MethodsWe studied 20 consecutive cases with idiopathic or heritable PAH. In patients with accompanying MR/DF (n=6) array-comparative genomic hybridisation analysis was performed, with the aim of finding common deletion regions containing candidate genes for PAH. Three patients had overlapping deletions of 17q23.2. TBX2 and TBX4 were selected from this area as candidate genes and sequenced in all 20 children. After identifying TBX4 mutations in these children, we subsequently sequenced TBX4 in a cohort of 49 adults with PAH. Because TBX4 mutations are known to cause small patella syndrome (SPS), all patients with newly detected TBX4 mutations were screened for features of SPS. We also screened a third cohort of 23 patients with SPS for PAH.ResultsTBX4 mutations (n=3) or TBX4-containing deletions (n=3) were detected in 6 out of 20 children with PAH (30%). All living patients and two parents with TBX4 mutations appeared to have previously unrecognised SPS. In the adult PAH-cohort, one TBX4 mutation (2%) was detected. Screening in the cohort of (predominantly adult) SPS patients revealed no PAH.ConclusionsThese data indicate that TBX4 mutations are associated with childhood-onset PAH, but that the prevalence of PAH in adult TBX4 mutation carriers is low.

A subgroup of patients with idiopathic pulmonary arterial hypertension (IPAH) has severely reduced diffusing capacity of the lung for carbon monoxide (DLCO) and poor prognosis. Their characteristics are currently unknown. The aim of this study is to contrast clinical characteristics and treatment responses of IPAH-patients with a severely reduced and more preserved DLCO.Retrospectively, 166 IPAH patients were included and grouped based on a DLCO cut-off value of 45% pred (IPAH ,45% and IPAH o45% ). Clinical characteristics, treatment responses and survival were compared.IPAH ,45% were older, more often male, had a more frequent history of coronary disease and a higher tobacco exposure. Forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity, total lung capacity and alveolar volume values were slightly lower and computed tomography scan abnormalities more prevalent in patients with a low DLCO. Age and number of pack years were independently associated with DLCO ,45% pred. IPAH ,45% showed no different haemodynamic profile, yet worse exercise performance and a worse survival rate, which were both related to age, sex and the presence of coronary disease.To conclude, a severely reduced DLCO in IPAH is associated with advanced age and a greater tobacco exposure. These patients have a worse exercise performance despite a similar hemodynamic profile. We confirm the decreased survival in this patient group and now show that this poor outcome is related to age, sex and the presence of coronary disease. @ERSpublications Severely reduced DLCO in IPAH is associated with advanced age and a greater tobacco exposure