Twenty-six patients with hematologic disorders and X chromosome abnormalities. Frequent idic(X)(q13) chromosomes and Xq13 anomalies associated with pathologic ringed sideroblasts.

In our experience, acquired structurally abnormal X chromosomes are found in about 1% of patients with hematologic disorders who have a chromosomally abnormal clone. Over a 10-year period, we identified 26 patients with hematologic disorders who had an acquired X chromosome abnormality. In 13 of these patients, the breakpoints were at Xq13, and in 13 the had idic(X)(q13) chromosomes. The 13 patients with Xq13 breakpoints were all older females, and 12 had pathologic ringed sideroblasts with dysmyelopoietic syndromes or a history of these syndromes. Among the 13 patients with breakpoints other than Xq13, seven were male and six were female; only one of these patients had pathologic ringed sideroblasts, and all of these patients had a variety of hematologic disorders. Xq13 may contain genes that, when altered by the formation of chromosome abnormalities, may be associated with neoplastic disorders involving pathologic ringed sideroblasts.