Following the first isolation of nuclear receptor (NR) genes, genetic disorders caused by NR gene mutations were initially discovered by a candidate gene approach based on their known roles in endocrine pathways and physiologic processes. Subsequently, the identification of disorders has been informed by phenotypes associated with gene disruption in animal models or by genetic linkage studies. More recently, whole exome sequencing has associated pathogenic genetic variants with unexpected, often multisystem, human phenotypes. To date, defects in 20 of 48 human NR genes have been associated with human disorders, with different mutations mediating phenotypes of varying severity or several distinct conditions being associated with different changes in the same gene. Studies of individuals with deleterious genetic variants can elucidate novel roles of human NRs, validating them as targets for drug development or providing new insights into structure-function relationships. Importantly, human genetic discoveries enable definitive disease diagnosis and can provide opportunities to therapeutically manage affected individuals. Here we review germline changes in human NR genes associated with “monogenic” conditions, including a discussion of the structural basis of mutations that cause distinctive changes in NR function and the molecular mechanisms mediating pathogenesis.
John C. Achermann, John Schwabe, Louise Fairall, Krishna Chatterjee
Structural modeling of NR mutations.(A) Modeling (PDB 2H77 TRα, PDB 1KKQ SMRT) shows that mutation of residues (red spheres) in the carboxyterminal region of TRα, which prematurely truncate helix 11 or 12 (left), facilitate its ability to accommodate corepressor (SMRT, blue) within a groove at the receptor surface (right).