About Sickkids
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June 29, 2001

Researchers identify gene for rare form of leukemia that strikes infants

A team of researchers at Toronto’s Hospital for Sick Children (SickKids) and St. Jude Children’s Research Hospital in Tennessee has identified the genetic cause of rare form of leukemia that strikes infants, as well as the corresponding diagnostic test. This research is reported in the July issue of the scientific journal Nature Genetics.

Acute megakaryoblastic leukemia (AMKL) is a rare form of leukemia that occurs more frequently in children younger than two years of age and is often characterized by fibrosis of the bone marrow. This type of leukemia also occurs in children with Down syndrome but the prognosis is particularly poor for infants without Down syndrome, with a median patient survival of only eight months. AKML accounts for up to 20 per cent of non-lymphoid leukemia in infants. Lymphoblastic and non-lymphoid are the two forms of childhood leukemia, which is the most common childhood cancer.

In non-Down syndrome infants with AMKL, the researchers found two novel genes involved in a chromosomal translocation (the exchange of genetic material between non-homologous chromosomes) that is highly specific for this type of infant leukemia. One gene on chromosome 1 and one gene on chromosome 22 are fused together creating an abnormal fusion gene.

“The most immediate outcome of this research is a simpler and more precise diagnostic test. In the longer-term, we hope that this research at the molecular level will lead to improved treatments for this disease,” said Dr. Hans Hitzler, the study’s principal investigator, a paediatric haematologist-oncologist and a scientist-track investigator in the HSC Research Institute. Dr. Hitzler is also an assistant professor of Paediatrics at the University of Toronto.

The next stages of research will involve determining the normal function of the proteins encoded by both genes in the cell and defining the mechanism by which the fusion gene found in the patients leads to leukemia.

Dr. Hitzler collaborated with Dr. Stephan Morris at St. Jude Children’s Research Hospital, which allowed the research team to obtain enough patient samples to do a genetic analysis with the participation of The Hospital for Sick Children’s Centre for Applied Genomics. To date, AKML has been difficult to study because of the rarity of the disease and the small size of samples, as it is difficult to get a large enough bone marrow sample from babies.

This research was supported by The Hospital for Sick Children Foundation, St. Jude Children’s Research Hospital, the American Lebanese Syrian Associated Charities, the National Cancer Institute in the United States, and the Canadian Institutes of Health Research.

The Hospital for Sick Children is a health care, teaching and research centre dedicated exclusively to children; affiliated with the University of Toronto. Its mission is to provide the best in family-centred, compassionate care, to lead in scientific and clinical advancement, and to prepare the next generation of leaders in child health.

For more information, please contact:

Public Affairs
The Hospital for Sick Children
555 University Avenue
Suite 1742, Public Affairs, First floor Atrium
Toronto, ON
M5G 1X8
Canada
Phone: 416-813-5058
Fax: 416-813-5328