Clinical and molecular aspects of RAS related disorders.

RAS proteins play key roles in normal cell growth, malignant transformation and learning and memory. Somatic mutations in RAS genes and several of their upstream and downstream molecules result in different human malignancies. In recent years germline mutations in genes coding for components of the RAS signalling cascade have been recognised in a group of phenotypically overlapping disorders, referred to as the neuro-cardio-facial-cutaneous syndromes. These present with variable degrees of psychomotor delay, cardiac abnormalities, facial dysmorphism, short stature, skin defects and increased cancer risk. These findings point to important roles for this evolutionary conserved pathway not only in oncogenesis, but also in cognition, growth and development. Other constitutional disorders caused by mutated RAS pathway genes point to involvement of the RAS-MAPK pathway in immune modulation and vascular development.