1. Report of the committee on human gene mapping by recombinant DNA techniques. HGM9;more information see Pearson PL, For; KK, Kidd; HF, Willard;Cytogenet Cell Genet,1987
2. ADA had been well characterised; three isozymic forms had been described by Hopkinson et al,27 one of which had low activity but not reduced to the same extent as in SCID. Tischfield et at26 assigned the locus for ADA to chromosome 20 at HGM1 by somatic cell hybridisation and this in turn assigned the locus for the disease. The locus was regionalised to 20ql3.1-*qter mainly by dosage studies of the enzyme in the cells of patients with various deletions or rearrangements of chromosome 2021 27-30 and by use of somatic cell hybrids containing translocations involving chromosome 20.31-33 More recently, three groups
3. The infectious agent may yet prove to be a virus although nobody has found nucleic acid in the prion protein
4. The agent may be a virino with a minimal amount of nucleic acid, difficult to detect, but able to induce disease by disrupting the regulatory functions of the nucleic acids of the host
5. The prion protein is self replicating. To accept the latter hypothesis by current dogma the demonstration of nucleic acid is still needed. Bandea61 suggests that the pathogen is an inherited endogenous virus which he calls a prionic virus. The prionic virus produces the prion analogous to a pathogenic bacterium producing a toxin. Prions produced by prionic viruses may in turn stimulate other viruses to form different prions with pathological characteristics. This hypothesis fits much of the data but is not yet proven. The relation of the protein to the encephalopathies may be found within the next few years now that cDNA, mRNA, and monoclonal antibodies to,a162).