Elucidation of an unbalanced chromosome translocation by gene dosage studies

Abstract
A chromosome abnormality, 46,XY,1p+, was detected in cultured amniotic fluid cells. The chromosomes of both parents were normal and it was impossible to recognize the extra chromosomal material using current banding techniques. The activity of acid .alpha.-glucosidase was found to be consistently higher than controls whereas activity of several other lysosomal enzymes, galactokinase and thymidine kinase was not. The extra material is probably that part of the long arm of chromosome 17 beairng the gene for acid .alpha.-glucosidase but not the genes for galactokinase and thymidine kinase. This would narrow the assignment of the acid .alpha.-glucosidase locus to 17q22 .fwdarw. 17 qter.