Clinical and molecular analysis of RASopathies in a group of Turkish patients

The 'RASopathies' are a group of disorders sharing many clinical features and a common pathophysiology. In this study, we aimed to clinically evaluate a group of Turkish patients and elucidate the underlying genetic etiology. Thirty-one patients with a clinical diagnosis of one of the RASopathy syndromes were included in the study. Of these, 26 (83.8%) had a clinical diagnosis of Noonan syndrome, whereas 5 had a clinical diagnosis of either Costello, LEOPARD or cardio-facio-cutaneous syndromes. Twenty of 31 (64.5%) patients were found to be mutation positive. Mutations in PTPN11, SOS1 and SHOC2 genes were detected in patients with Noonan syndrome (57.6%). Mutations in MEK1, PTPN11, BRAF and HRAS genes were detected in the remaining. Pulmonary stenosis was the most common (61.5%) cardiac anomaly. Among Noonan syndrome patients with a confirmed mutation, mild intellectual disability tended to be more common in patients with PTPN11 mutation than in those with SOS1 mutation. Hematologic evaluation revealed coagulation defects in three Noonan syndrome patients with a mutation. This is currently the largest clinical and molecular study in Turkish RASopathy patients. Our findings indicate that molecular epidemiology and genotype-phenotype correlations in RASopathies are relatively independent from the ethnic population background.