Triplex gene dosage effect of beta-glucuronidase and possible assignment to band q22 in a partial duplication 7q

A 2-year-old girl had a de novo duplication in the long arm of one chromosome 7 and an increased level of the enzyme beta-glucuronidase in cultured fibroblasts. The phenotype of the girl partly overlaps those of two presumptive syndromes due to secondary partial trisomies 7q. The ratio of the enzyme activity was 1.43 to the controls, and 1.37 to her parent's values. We could not define the abnormality but suggest two alternatives: either the patient is trisomic for region q112 to q22 or for the region q22 to q34. If the second alternative is correct the locus for beta-glucuronidase is possibly assigned to band 7q22.