Cloning and characterization of a splice variant of human Bardet-Biedl syndrome 4 gene (BBS4)

Genetic kidney diseases

Knowledge of the primary cause of a disease is essential for elucidation of its mechanisms, and for adequate classification, prognosis, and treatment. Recently, the causes of many kidney diseases have been shown to be single-gene defects-eg, steroid-resistant nephrotic syndrome, which is caused by podocin mutations in about 25% of children and nearly 15% of adults with the disease. Knowledge of a disease-causing mutation in a single-gene disorder represents one of the most robust diagnostic examples of personalised medicine because the mutation conveys an almost 100% risk of developing the disease by a defined age. Whereas single-gene diseases are rare disorders, polygenic risk alleles arise in common adult-onset diseases. In this Review, I will discuss prominent renal single-gene kidney disorders, and polygenic risk alleles of common disorders. I delineate how emerging techniques of total exome capture and large-scale sequencing will assist molecular genetic diagnosis, prognosis, and specific treatment, and lead to an improved elucidation of disease mechanisms, thus enabling development of new targeted drugs.

Cell signaling, the essential role of O-GlcNAc!

An increasing body of evidence points to a central regulatory role for glucose in mediating cellular processes and expands the role of glucose well beyond its traditional role(s) in energy metabolism. Recently, it has been recognized that one downstream effector produced from glucose is UDP-GlcNAc. Levels of UDP-GlcNAc, and the subsequent addition of O-linked beta-N-acetylglucosamine (O-GlcNAc) to Ser/Thr residues, is involved in regulating nuclear and cytoplasmic proteins in a manner analogous to protein phosphorylation. O-GlcNAc protein modification is essential for life in mammalian cells, highlighting the importance of this simple post-translational modification in basic cellular regulation. Recent research has highlighted key roles for O-GlcNAc serving as a nutrient sensor in regulating insulin signaling, the cell cycle, and calcium handling, as well as the cellular stress response.

Genetic disorders involving molecular-chaperone genes: a perspective

Molecular chaperones are important for maintaining a functional set of proteins in all cellular compartments. Together with protein degradation machineries (e.g., the ubiquitin-proteasome system), chaperones form the core of the cellular protein-quality control mechanism. Chaperones are proteins, and as such, they can be affected by mutations. At least 15 disorders have been identified that are associated with mutations in genes encoding chaperones, or molecules with features suggesting that they function as chaperones. These chaperonopathies and a few other candidates are presented in this article. In most cases, the mechanisms by which the defective genes contribute to the observed phenotypes are still uncharacterized. However, the reported observations definitely point to the possibility that abnormal chaperones participate in pathogenesis. The available data open novel perspectives and should encourage searches for new genetic chaperonopathies, as well as further analyses of the disorders discussed in this article, including detection of new cases.