Wolf-Hirschhorn syndrome: A review and update.

Since 4p- was first described in 1961, significant progress has been made in our understanding of this classic deletion disorder. We have been able to establish a more complete picture of the WHS phenotype associated with distal 4p monosomy, and we are working to delineate the phenotypic effects when each gene on distal 4p is hemizygous. Our aim is to provide genotype-specific anticipatory guidance and recommendations to families of individuals with a diagnosis of WHS. In addition, establishing the molecular underpinnings of the disorder will potentially suggest targets for molecular treatments. Thus, the next step is to determine the precise effects of specific gene deletions. As we look forward to deepening our understanding of distal 4p deletion, our focus will continue to be on the establishment of robust genotype-phenotype correlations and the penetrance of these phenotypes. We will continue to follow our WHS cohort closely as they age to determine the presence or absence of some of these comorbidities, including hepatic neoplasms, hematopoietic dysfunction, and recurrence of seizures. We will also continue to refine the critical regions for other phenotypes as we enroll additional (hopefully informative) participants into the research study and as the mechanisms of the genes in these regions are elucidated. New animal models will also be developed to further our understanding of the effects of hemizygosity as well as to serve as models for treatment development.