Disease models for every field

The Instituto Juan March meeting on the ‘Molecular basis of human congenital lymphocyte disorders’ was organized by Hans D. Ochs (Seattle, WA) and Jose R. Regueiro (Madrid, Spain) and took place in Madrid, Spain, December 2–5, 2001. A related meeting on ‘Immunodeficiencies of genetic origin’ was organized by the Instituto Juan March in 1995.![][1] Primary immunodeficiencies (PID), which formerly concerned mainly geneticists, immunologists and hematologists, have now become a resource for essentially all fields in biomedicine. This is not surprising, given that the number of different forms of PID has reached more than 100 and affects such fundamental aspects of cell biology as transcription factors, vesicular transport and endoribonucleases. Table 1 lists the subsets of PID that were the focus of this meeting, subdivided according to biological function; for a more extensive description, see Ochs et al . (1999).View this table:Table 1. Components defective in PID discussed at the meeting### Defects of repair and modification of DNAAs discussed by A. Villa (Milan, Italy) and D. Moshous (Paris, France), several disorders of the immune system involve the DNA recombination and repair process, reflecting the role of recombination of variable, diversity and joining gene segments in the generation of antigen‐specific receptors on T and B lymphocytes. This process is complex, involving both ubiquitously expressed proteins (e.g. the DNA‐dependent protein kinase, Artemis) and polypeptides confined to lymphocytes (e.g. Rag1 and Rag2). Ataxia telangiectasia and related disorders cause defects in various organs and in the immune system. Although the dysfunctional proteins responsible for these diseases are considered to be part of the same supramolecular complex, the phenotypes of the different disorders are not identical. The product of the ATM gene, linked to ataxia telangiectasia, is the most well‐characterized of these proteins. It is involved in a variety of responses to DNA double‐strand breaks, including cell cycle arrest, apoptosis and DNA repair. A.M.R. Taylor (Birmingham, UK) discussed how a DNA double‐strand break … [1]: /embed/graphic-1.gif