Constitutional chromosomal aberration, t(4;12) (q23;p11), in a patient with Ph1 positive chronic myelocytic leukemia

A 54-year-old man with Ph1 positive chronic myelocytic leukemia and two balanced reciprocal translocations in bone marrow cells is described. One was the typical translocation between chromosomes No. 9 and 22, t(9;22), while the other was a constitutional translocation between chromosomes No. 4 and 12, t(4;12)(q23;p11), which was also present in all PHA-stimulated peripheral blood lymphocytes. Two brothers, one sister, one son, and one daughter also had the same constitutional translocation between chromosomes No. 4 and 12. None of them had signs of hematological disorder. The follow-up investigation of the family may clarify whether this constitutional translocation involves increased risk of developing CML.