Epigenetics and its Genetic Syndromes
This chapter explores the contribution of a growing number of genetic syndromes in defining the function of the components of chromatin and of the enzymes that modify chromatin structure. The study of human genetic conditions has had a major impact not only by providing a better understanding of the pathogenesis of disease but also by helping elucidate the function of proteins. Hypomethylation of a satellite DNA appears to be seen only in individuals negative for DNA methyltransferase 3B mutations, strengthening the supposition that there is genetic heterogeneity in Immunodeficiency, Centromeric Instability, and Facial Anomalies syndrome. Cockayne syndrome (CS) is a DNA repair disorder and is characterized by stunted growth that is apparent in the first few years of life. Fibroblasts from individuals with CS exhibit increased sensitivity to ultraviolet irradiation, and particularly marked is the failure of RNA synthesis to recover to normal rates after ultraviolet exposure.