  Recent philosophical efforts to define genes have sought to capture these practices. C. Kenneth Waters (1994) recognizes that specific research contexts determine whether genes are considered to include introns as well as exons, or regulatory or promoter regions as well as open reading frames (ORFs), but argues that what remains “fundamental” across these contexts is the concept of a gene as a stretch of DNA the linear sequence of which provides a template for a gene product, whether mRNA transcript or polypeptide. Because of problems posed for Waters’ account by mRNA splicing and editing, Eva Neumann-Held (1999) recommends replacing the “classical molecular gene concept” of a stretch of DNA coding for a single polypeptide with a “molecular process gene concept” which includes not just the relevant stretches of DNA but the entire cellular context in which polypeptides are produced. Lenny Moss (2003) identifies two gene concepts: the preformationist gene, Gene-P, defined by its relationship to a phenotype, is of instrumental utility for molecular geneticists—for example, the BRCA1 gene is used to predict breast cancer risk; the epigenesist gene, Gene-D, defined by its molecular sequence, serves as a “developmental resource” in providing a template for RNA and protein synthesis but is indeterminate with respect to phenotype since this depends on other developmental resources and the cellular and extracellular  contexts.[14] Paul Griffiths and Karola Stotz (2006) distinguish three gene concepts: “instrumental genes” remain important in molecular genetics when relationships between genotype and phenotype are under investigation; “nominal molecular genes” are specific DNA sequences annotated by researchers as genes for structural reasons such as presence of ORFs; “postgenomic molecular genes” are not defined by structure but “by the way DNA sequences are used in particular cellular and broader contexts” (p. 515).