A family has recently been described in whom three members affected by acute myeloid leukaemia (AML) carried germline heterozygous mutations in CCAAT enhancer-binding proteinalpha (CEBPA), the gene encoding the granulocyte differentiation factor C/EBPa. 1 The transcription factor C/EBPa is a key regulator of early myeloid differentiation, regulating a number of granulocyte-specific genes and inducing granulocytic development of bipotential myeloid progenitors by activation of target gene promoters. 2 C/EBPa consists of N-terminal transactivating domains (TAD1 and TAD2) and a C-terminal basic and leucinezipper region necessary for specific DNA sequence binding and homo-or heterodimerization, respectively. 2 Here, we report the clinical and molecular features of a second family in which a germline mutation in CEPBA caused AML. The family, in which four members had documented evidence of developing AML was originally reported in 1998 (Figure 1). 3 Briefly, individual III: 1 presented at 34 years of age with AML. Individual IV: 2 presented at age 25 years with AML M4 with eosinophilia with cytogenetic analysis revealing an abnormal clone 46XY, del (6)(q21) in 5/16 cells. Individual IV: 4 presented at age 24 years with AML M1. No clonal cytogenetic abnormality was detected. Individual V: 1 presented at age 4 years with AML M1. Cytogenetic analysis of individual V: 1 at presentation was normal but on relapse the clonal abnormality 47, XY, þ8 was observed, with clonal evolution to 47, XY, þ8, þ21 at subsequent relapse. Individuals IV: 2 and V: 1 remain well 18 and 14 years from original diagnosis of AML, respectively, despite experiencing one or more relapses. Individual IV: 4 remains well in first remission 11 years from original diagnosis of AML. He has been shown to have a normal 46, XY karyotype. All members of the family (Figure 1) are white Caucasians and there is no evidence of consanguinity. We have previously excluded involvement of Fanconi, mutations in TP53 and RUNX1 and linkage to 16q21–23.2 as a cause of AML in the family. 3, 4

Samples of mononuclear-cell-enriched peripheral blood samples were obtained at diagnosis from individuals IV: 2 and IV: 4. Peripheral blood samples for germline mutation analysis were obtained from III: 2 and IV: 3 and from individuals IV: 2, IV: 4 and V: 1 during remission. DNA was extracted using a routine salt-precipitation methodology. The complete coding sequence of CEBPA (referenced to GenBank accession Y11525) was screened in individuals III: 2, IV2, IV: 3, IV: 4 and V: 1 as a series of overlapping PCR fragments. PCR primers were designed by use of Primer 3 software (http://www. broad. mit. edu/cgi-bin/primer/primer3_www. cgi). All primer sequences and PCR conditions are available upon request. Amplified PCR products were purified (Qiagen Inc., Valencia, CA, USA) and bidirectionally sequenced using BigDye Terminator chemistry implemented on an ABI Prism 3100 sequencer. Sequences were aligned and compared to consensus