The role of genomic imprinting in human developmental disorders: lessons from Prader-Willi syndrome

Normal human development involves a delicate interplay of gene expression i n specific tissues at narrow windows of time. Temporally and spatially regu lated gene expression is controlled both by gene-specific factors and chrom atin-specific factors. Genomic imprinting is the expression of specific gen es primarily from only one allele at particular times during development, a nd is one mechanism implicated in the intricate control of gene expression. Two human genetic disorders, Prader-Willi syndrome (PWS, MIM 176270) and A ngelman syndrome (AS, MIM 105830), result from rearrangements of chromosome 15q11-q13, an imprinted region of the human genome. Despite their rarity, disorders such as PWS and AS can give focused insight into the role of geno mic imprinting and imprinted genes in human development.