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Centre de recherche
Monday, December 17 2012

A genetic defect in sex cells may predispose to childhood leukemia

Rare atypical form of the PRDM9 fertility gene found in parents

Montreal, Canada, December 17, 2012 – Researchers at the Sainte-Justine University Hospital Center and the University of Montreal have found a possible heredity mechanism that predisposes children to acute lymphoblastic leukemia (ALL), the most common type of blood cancer in children. According to their findings published in Genome Research, the presence of a genetic defect in the egg or sperm that give rise to children with ALL may be a prerequisite for the disease to develop. A significant number of children with ALL are thought to inherit a rare PRDM9 gene variant responsible for the abnormal sex cells–a gene variant that puts their own children at risk of having ALL-predisposed offspring.

“Our findings indicate ALL susceptibility to be partially hereditary. However, it is not classic heredity in the sense that the abnormal genetic variant does not need to be passed from parent to child for offspring to have the disease,” explains Julie Hussin, a doctoral student in Genomics under the direction of Dr. Philip Awadalla, a genetics researcher.

“Instead, the genetic defect in the egg or sperm from which the children developed is thought to predispose them to leukemia,” continues Julie Hussin. “However, only the children who inherit the genetic variant run the risk of transmitting ALL predispositions to their offspring.” According to the study, more than three quarters of families with affected children have an atypical form of the PRDM9 gene, with half the patients inheriting this genetic variant. The defect is expressed at unusual positions along chromosomes during formation of eggs in females, or sperm in males.

While an abnormal gamete may lead to ALL development, this condition alone is not enough. “Triggering the process of cancer cell proliferation inevitably requires a second hit, such as other mutations or environmental factors,” explains Julie Hussin.

Until now, few pediatric cancer studies have analyzed data from parents, as scientists generally focus on studying children, the tumours or their environment, especially during pregnancy. “Parents have to be included in these studies. Our findings demonstrate the importance of including parents’ genetic information for the understanding of childhood leukemia, as well as other early childhood diseases,” added Philip Awadalla, the lead principal investigator on the study.

The findings were replicated in a cohort of American children with ALL through the collaboration of the Sainte-Justine University Hospital Center in Montreal, Canada, and St. Jude Children’s Research Hospital in Memphis, USA.

ACUTE LYMPHOBLASTIC LEUKEMIA MODEL OF HEREDITY

PARENTS
At least one parent with/without leukemia produces abnormal gametes and carries a rare PRDM9 allele

TWO CHILDREN
Both have leukemia, since each develops from an abnormal gamete

CHILD 1

  • Receives the rare allele in its genome
  • Produces abnormal gametes
  • Risks having children with leukemia

CHILD 2

  • Does not receive the rare allele
  • Produces normal gametes
  • Does not risk having children with leukemia

About the researchers:
Julie Hussin, doctoral student in bio-informatics

  • Sainte-Justine University Hospital Center, department of hematology/oncology
  • Department of biochemistry, Université de Montréal


Dr Philip Awadalla

For information

Marise Daigle
Conseillère en communications
Centre de recherche du CHU Sainte-Justine
+ 1 514 345-4931, poste 3256 marise.daigle@recherche-ste-justine.qc.ca

Entrevues
Julie Hussin et Dr Philip Awadalla sont disponibles pour entrevues sur rendez-vous.

Contact média
Mélanie Dallaire (Québec)
Conseillère principale, relations média, CHU Sainte-Justine
melanie.dallaire.hsj@ssss.gouv.qc.ca

William Raillant-Clark (Canada et ailleurs dans le monde)
Attaché de presse international, Université de Montréal
+ 1 514 343-7593 w.raillant-clark@umontreal.ca

Persons mentioned in the text
About this page
Updated on 11/17/2014
Created on 11/17/2014
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