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Germline DICER1 mutation and associated loss of heterozygosity in a pineoblastoma
  1. Nelly Sabbaghian1,2,
  2. Nancy Hamel1,3,
  3. Archana Srivastava1,2,
  4. Steffen Albrecht4,
  5. John R Priest5,
  6. William D Foulkes1,2,3
  1. 1Program in Cancer Genetics, Department of Oncology and Human Genetics, McGill University, Montreal, Quebec, Canada
  2. 2Lady Davis Institute, Segal Cancer Centre, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
  3. 3Research Institute, McGill University Health Centre, Montreal, Quebec, Canada
  4. 4Department of Pathology, Montreal Children's Hospital and McGill University, Montreal, Quebec, Canada
  5. 5Minneapolis, Minnesota, USA
  1. Correspondence to Dr William D Foulkes, Program in Cancer Genetics, Department of Oncology and Human Genetics, Gerald Bronfman Centre for Clinical Research in Cancer, McGill University 546 Pine Avenue West, Montreal, Quebec H2W 1S6, Canada; william.foulkes{at}

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Pineoblastomas occur in RB-1 mutation carriers,1 but are rarely seen in association with other hereditary syndromes.2 Germline DICER1 mutations are associated with embryonal tumours such as pleuropulmonary blastoma (PPB),3 ,4 so we hypothesised that such mutations might also occur in children with pineoblastoma. Here we describe a novel deleterious germline DICER1 mutation in a young child with a highly aggressive pineoblastoma. In addition, we observed loss of heterozygosity (LOH) of the wild-type allele, an event not previously reported in DICER1 associated tumours.5 ,6 Our observations suggest: (1) pineoblastomas are associated with germline DICER1 mutations; and (2) unexpectedly, tumour cells can thrive in the absence of functional DICER1.

The pineal gland, so named by Galen because of its resemblance to a pine nut, is a ∼175 mg midline structure situated on the posterior wall of the third ventricle, deep between the cerebral hemispheres. Pineal gland tumours are often derived from ectopic germ cell tissue, but pineocytomas and pineoblastomas also occur. A pineoblastoma is a supratentorial primitive neuroectodermal tumour arising in the pineal gland. Germline mutations in tumour suppressor genes have rarely been associated with pineoblastomas,1 ,2 but mutations in RB-1 can result in so-called ‘trilateral retinoblastoma’.1

We obtained …

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