No abstract

Drosophila melanogaster oocytes heterozygous for mutations in the α-tubulin 67C gene (αtub67C) display defects in centromere positioning during prometaphase of meiosis I. The centromeres do not migrate to the poleward edges of the chromatin mass, and the chromatin fails to stretch during spindle lengthening. These results suggest that the poleward forces acting at the kinetochore are compromised in the αtub67C mutants. Genetic studies demonstrate that these mutations also strongly and specifically decrease the fidelity of achiasmate chromosome segregation. Proper centromere orientation, chromatin elongation, and faithful segregation can all be restored by a decrease in the amount of the Nod chromokinesin. These results suggest that the accurate segregation of achiasmate chromosomes requires the proper balancing of forces acting on the chromosomes during prometaphase.

Literature review and clinical findings in four affected adult males from one family suggest that there are serious and currently ill-defined health risks in adults with Beckwith-Wiedemann syndrome (BWS). These may include male subfertility, vascular anomalies, renal abnormalities, hearing loss and, possibly, an increased risk for adult-onset malignancy. Given present knowledge, recommendations in caring for adults with this disorder remain tentative but likely should include counseling for possible infertility in males, screening echocardiography, renal sonogram and renal function testing, and counseling about possible increased risk for adult onset malignancy.