Biallelic mutations in PALB2 cause Fanconi anemia subtype FA-N and predispose to childhood cancer Sarah Reid 1 , Detlev Schindler 2 , Helmut Hanenberg 3,4 , Karen Barker 1 , Sandra Hanks 1 , Reinhard Kalb 2 , Kornelia Neveling 2 , Patrick Kelly 1 , Sheila Seal 1 , Marcel Freund 3 , Melanie Wurm 3 , Sat Dev Batish 5,6 , Francis P Lach 5 , Sevgi Yetgin 7 , Heidemarie Neitzel 8 , Hany Ariffin 9 , Marc Tischkowitz 10,11 , Christopher G Mathew 12 , Arleen D Auerbach 5 & Nazneen Rahman 1 PALB2 was recently identified as a nuclear binding partner of BRCA2. Biallelic BRCA2 mutations cause Fanconi anemia subtype FA-D1 and predispose to childhood malignancies. We identified pathogenic mutations in PALB2 (also known as FANCN) in seven families affected with Fanconi anemia and cancer in early childhood, demonstrating that biallelic PALB2 mutations cause a new subtype of Fanconi anemia, FA-N, and, similar to biallelic BRCA2 mutations, confer a high risk of childhood cancer. Fanconi anemia is a rare, recessive, chromosomal instability disorder characterized by growth retardation, congenital malformations, pro- gressive bone marrow failure, cancer predisposition and cellular hypersensitivity to DNA cross-linking agents 1 . The syndrome is genetically heterogeneous with 12 complementation groups currently recognized, 11 of which have been attributed to distinct genes: FANCA (FA-A), FANCB (FA-B), FANCC (FA-C), BRCA2 (FA-D1), FANCD2 (FA-D2), FANCE (FA-E), FANCF (FA-F), FANCG (FA-G), BRIP1 (FA-J), FANCL (FA-L) and FANCM (FA-M) 2,3 . BRCA2 is a DNA repair protein with a key role in the repair of DNA double-strand breaks by homologous recombination 4 . BRCA2 was originally identified through positional cloning of a familial breast cancer predisposition gene, and monoallelic (heterozygous) mutations are associated with high risks of breast and ovarian cancer 5 . Subse- quently, biallelic BRCA2 mutations were found to cause a rare subtype of Fanconi anemia, FA-D1 (ref. 6). The phenotype of biallelic BRCA2 mutations differs from other Fanconi anemia subtypes, most notably with respect to the high risks of childhood solid tumors, particularly Wilms tumor and medulloblastoma, which occur very rarely in other Fanconi anemia subtypes 6–10 . Although Fanconi anemia and childhood embryonal tumors are attributable to BRCA2 in many individuals, we identified individuals with this phenotype who lacked BRCA2 mutations. This raised the possibility that deficiency of other proteins might give rise to this combination of features, and we considered proteins functionally related to BRCA2 the most credible candidates. PALB2 (for ‘partner and localizer of BRCA2’) was recently identified as a nuclear partner of BRCA2 (ref. 11). PALB2 colocalizes with BRCA2, promoting its localization and stability in key nuclear struc- tures, which in turn facilitates BRCA2 functions in DNA repair. Furthermore, knockdown of PALB2 sensitizes cells to MMC treatment, which results in interstrand cross-links and double-strand breaks 11 . Sensitivity to MMC is a hallmark of Fanconi anemia, and these data therefore recommended PALB2 as a candidate Fanconi anemia gene. We sequenced the 13 exons and intron-exon boundaries of PALB2 in 82 individuals with Fanconi anemia not due to known genes (Supplementary Methods and Supplementary Table 1 online). We identified pathogenic mutations in seven families (Fig. 1a and Table 1). In four affected individuals (GESH, IFAR-847, LNEY and IFAR-849), we identified biallelic mutations that resulted in premature protein truncation. Analysis of parental DNA demonstrated that all the mutations had been inherited from different parents, consistent with autosomal recessive inheritance. No sample was available from the affected individuals LOAO, IFAR-007 and ICR-60, but their parents all carried truncating PALB2 mutations. We also sequenced PALB2 in 352 control chromosomes (176 normal indivi- duals) and did not identify any truncating mutations, providing further evidence that such mutations are pathogenic in the individuals with Fanconi anemia. We saw one mutation, 3549C-G (leading to amino acid change Y1183X), in two separate families. We also identified a different mutation in a third family at the same nucleotide, 3549C-A, which also results in Y1183X. 3549C is in the last exon of PALB2, and there are only three amino acids after codon 1183 before the protein terminates. Truncating mutations close to the end of a protein are generally expected to escape nonsense-mediated RNA decay 12 . However, there was no detectable PALB2 protein in lymphoblastoid cells from individuals IFAR-847 and IFAR-849, who both carry Received 14 August; accepted 27 November; published online 31 December 2006; doi:10.1038/ng1947 1 Section of Cancer Genetics, Institute of Cancer Research, Sutton, Surrey SM2 5NG, UK. 2 Department of Human Genetics, University of Wuerzburg, D-97074 Wuerzburg, Germany. 3 Department of Pediatric Oncology, Hematology and Immunology, Heinrich Heine University, D-40225 Duesseldorf, Germany. 4 Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. 5 Laboratory of Human Genetics and Hematology, The Rockefeller University, 1230 York Ave., New York, New York 10021, USA. 6 Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, New York 10021, USA. 7 Hacettepe University, Ihsan Dooramacy Children Hospital, Division of Pediatric Hematology, 06100 Ankara, Turkey. 8 Department of Human Genetics Charite ´-Universitaetsmedizin, D-13353 Berlin, Germany. 9 Paediatric Haematology-Oncology Unit, University of Malaya Medical Centre, Kuala Lumpur, Malaysia. 10 Cancer Prevention Center, The Sir Mortimer B. Davis Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada. 11 Program in Cancer Genetics, Departments of Oncology and Human Genetics, McGill University, Montreal, Quebec H3A 1B1, Canada. 12 Kings College London School of Medicine, Department of Medical and Molecular Genetics, Guy’s Hospital, London SE1 9RT, UK. Correspondence should be addressed to N.R. (nazneen.rahman@icr.ac.uk). 162 VOLUME 39 [ NUMBER 2 [ FEBRUARY 2007 NATURE GENETICS BRIEF COMMUNICATIONS © 2007 Nature Publishing Group http://www.nature.com/naturegenetics