GENOMIC IMPRINTING AND ANTICIPATION IN IDIOPATHIC TORSION DYSTONIA

Idiopathic torsion dystonia (ITD) is a dominantly inherited disorder w ith variable penetrance and expressivity. Factors affecting the penetr ance of the ITD gene have not yet been identified. The present study u sed four published series of cases to test specific hypotheses regardi ng factors that could affect the expression of ITD. Among the combined 253 families, transmission of ITD did not depend on either the sex of the affected offspring or that of the transmitting parent. Furthermor e, neither the specific type of dystonia manifested, the site at which clinical signs of dystonia first appeared, nor age of onset differed significantly as a function of the gender of the transmitting parent. However, in familial cases of later onset (age greater-than-or-equal-t o 20 years), nearly all involved a transmitting mother. There is evide nce for consistency of age of onset within the subset of Jewish famili es. Although anticipation effects are apparent, sampling bias cannot b e ruled out.