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本帖最后由 细胞海洋 于 2010-6-19 19:00 编辑 4 T( W0 J, ^, D3 D9 @# P; C
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: ?; r! g& h5 \7 ACancer genetics is a rapidly evolving field, which has revolutionized the practice
0 H9 y& ~6 C( Y1 O; i& `2 [- Eof medicine in the past decade. Genetic testing for several high-penetrance tumor
, r4 ^: V% [+ M0 n1 q% P8 Wsusceptibility genes such as BRCA1, BRCA2, and APC have allowed the identification8 l, ?% i' U, c) D5 K# T
of individuals at high risk for breast and colon cancers that can be effectively- h, d4 m, l1 Y, m6 b5 B3 p
prevented with early screening.
% k4 u1 i/ [. S; |Somatically acquired genetic changes such as overexpression of the ERBB2 gene
. i( ?' ~; n7 @) Oin breast cancer and mutations of the KRAS or BRAF genes in colorectal cancer! H- a, `1 ^/ K/ @) w$ [$ Q4 ~
are observed in a significant fraction of patients. These genetic alterations can be
2 q2 O% n- v0 s& }, Jeffectively targeted with antibodies such as trastuzumab and cetuximab. Treatment
- }9 I7 A" n3 [& o4 Hwith these genetically targeted agents increases patient survival.& r. W) S! z* c; R* w% q3 F
Because genetic information allows for the exact identification of individuals,
0 A: {# j$ P7 H: [& Mthe widespread expansion of genetic testing is potentially fraught with ethical and1 U) D4 a/ w' L/ O
legal issues. The first chapter of this book, which is written by Drs. Offit and Thom,& U! h8 o$ f0 U p% O
provides an insightful overview of the ethical aspects of cancer genetics.
# I9 o. Q: r& t4 v5 ~. O' N4 K/ _Systematic studies of common genetic variants are facilitated by the fact that; W+ T9 ]( |- d1 X* y5 r
individuals who carry a particular SNP allele at one site often predictably carry specific
% e+ f, l6 J* x+ d/ ~alleles at other nearby sites. This correlation is known as linkage disequilibrium' N6 N- O- R! u7 a
(LD); a particular combination of alleles along a chromosome is termed a haplotype.% J; W' o. R! {% c/ d2 K
The correlations between causal mutations and the haplotypes on which they arose
. u! t) J S G" Shave long served as a tool for human genetic research: first finding an association to7 _4 Z- c+ T4 L: h
a haplotype and then subsequently identifying the causal mutation(s) that it carries.
. D) _6 }9 D- ~. g( xWith the sequencing of the human genome and development of high-throughput
- |: Y* z5 i' D% {6 M; H! y, H- xgenomic methods, it has become clear that the human genome generally displays. H3 u b2 a2 u1 O
more LD than under simple population genetic models, and that LD is more varied- ^$ c$ z. y5 M: V* r- _
across regions, and more segmentally structured, than had previously been supposed.
! {' {8 M/ f* s9 _These observations indicated that LD-based methods would generally have a, H- ~, Y) h# [) Z
great value (because nearby SNPs were typically correlated with many of the neighbors),
8 x. [$ L) E) kand also that LD relationships would need to be empirically determined across the genome by studying polymorphisms at high density in population samples. This
& A# W" [. D% q- h8 S qhas provided the rationale for the development of the International HapMap project
) o; C+ M# H3 G2 x; ], o(www.hapmap.org). Novel genotyping technologies combined with the knowledge0 d$ I8 O' ^4 f* {$ P
generated by the HapMap project have provided the necessary tools to interrogate. Q& j3 i1 y0 ^1 g* }6 B4 t
the association of genetic variants from the entire genome with risk for various diseases.
9 B9 q' q$ z$ oThe influence of such common polymorphisms on breast cancer, one of the
( s$ \$ B7 Z* X, V9 ^leading causes of cancer death, is thoroughly reviewed in the second chapter written; F" I: ?- p$ U3 k4 U# q, z
by Drs. Eccles and Tapper.
! D7 m1 k5 L! w& K: tIn the third chapter, Drs. Schrader and Huntsman provide the latest genetic7 W* x7 G* d0 K; j
knowledge related to gastric cancer and focus on genetic cause, identification, and
7 Z+ B- x/ d# D0 q6 {# nmanagement of a rare but deadly syndrome, hereditary gastric cancer.! o K7 W/ x$ p
Recent advances in cancer genetics are not limited to adult tumors. In the
4 \; @0 [6 d2 Q. {fourth chapter, Drs. Capasso and Diskin provide a timely update on the recent and
9 M% z4 o1 D% zexciting genetic discoveries related to one of the most common pediatric cancer,0 L7 f# ?5 N0 z: j. t7 y$ K
neuroblastoma.- m8 K+ V. x; E8 ]% q1 R
In the fifth and last chapter, Drs. Bellam and Pasche review the latest discoveries
3 x9 O+ Z S. |9 d" ~+ a6 Rrelated to constitutively altered TGF-β signaling in colorectal cancer risk, a novel
+ i5 Z6 d9 V% G5 T2 ophenotype that may account for a large proportion of colorectal cancers.6 m7 H4 Y1 Z }4 c6 K
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发表于 2010-6-19 18:43
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