The Genom of Homo sapiens.pdf

HUMAN MUTATIONAL PROFILING 27Figure 4. Results from our pilot study of AML suspect genes in42 patient samples, indicating the gene sequences (left column),and the synonomous and nonsynonomous amino acid-alteringmutations found. In the case of the FLT3 gene, we found theexon 11 ITD in 20% of patients as well as the exon 17 (D835Y)mutation in 10% of the patients studied.mouse model and patient samples. Overall, the validationphase will serve as a means of increasing the size of ourAML data set of mutational profiles centered on a smallernumber of candidate genes. Following on, a second roundof correlation of these profiles back to AML subtypes andclinical outcomes should serve to further focus our attentionon a handful of genes now highly suspect for their involvementin AML pathogenesis.Our preliminary findings from this study, using 13genes, have been described elsewhere (Ley et al. 2003)and are summarized in Figure 4. Briefly, for the 13 genesstudied in 46 patient samples (tumor and somatic/controlDNA samples) representing different AML subtypes(M0/M1, M2, M3/APL, and M4), we found that previouslydescribed mutations in CBF-β, FLT3, c-KIT,c-MYC, N-RAS, PML, and RARα were also found in ourpatient samples, as indicated. Most notably, in FLT3 wedetected the previously described internal tandem duplication(ITD) in exon 11 but also found another FLT3 mutationcausing a nonsynonomous amino acid change(D835Y) in 10% of the patient samples sequenced.FUTURE DIRECTIONSSequence-based mutational profiling represents an immediateapplication of the human genome sequence, andthe technology developed to produce it, toward the studyof human health and disease. In the near term, we can utilizemutational profiling to better understand the molecularbasis of many human diseases for which there are candidategenes, or at least a reasonable number of suspectedcandidates. For genes such as SPB that play a role in bothmoderate and severe forms of a disease, such an understandingwill be critical to improved diagnosis, treatment,and management of patients who carry these sequencechanges. Likewise, as we begin to discover and study theinterplay of sequence changes and mutations in the bevyof genes that underlie various human cancers, we willcreate new opportunities for earlier diagnosis that willsubstantially save lives and decrease health care costseven with current state-of-the-art cancer treatments. Ultimately,a better understanding of the genes involved incancer and other diseases will allow the development oftargeted therapeutics (such as Gleevec) that are aimeddirectly at the molecular flaw.Although the technology and its associated expensecurrently require that we focus our efforts and sequencingpipelines nearly exclusively on the exons of candidategenes, it is clear that we must in the future develop mutationalprofiling strategies and methods that will allow usto cast a broader net, aimed at discovering causal mutationsand sequence changes that lie outside of coding sequenceand candidate genes. Ideally, we would prefer tosequence a patient’s complete genome (both “germ line”and from the affected tissue), cross-reference all sequencevariations and discovered mutations, and characterizeany epigenomic changes as well. Such a comprehensiveanalysis should not only be relativelyinexpensive, it should also be performed in a sufficientlynarrow time frame so as to allow a physician to quicklyrespond to acute symptoms. Of course, we are currentlyfar from being able to offer patients such a comprehensivegenome-based diagnostic analysis, but the promiseof genomic medicine is vast, and we believe that exonbasedmutational profiling such as we describe here representsan early step on the road to such promise.REFERENCESAbu-Duhier F.M., Goodeve A.C., Wilson G.A., Care R.S.,Peake I.R., and Reilly J.T. 2001. Identification of novel FLT-3 Asp835 mutations in adult acute myeloid leukaemia. Br. J.Haematol. 113: 983.Abu-Duhier F.M., Goodeve A.C., Wilson G.A., Gari M.A.,Peake I.R., Rees D.C., Vandenberghe E.A., Winship P.R., andReilly J.T. 2000. FLT3 internal tandem duplication mutationsin adult acute myeloid leukaemia define a high-risk group. Br.J. Haematol. 111: 190.Avery M.E. and Mead J. 1959. 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