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Penulis Topik: Gene Association Studies Typically Wrong  (Dibaca 6766 kali)

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Offline peregrin

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Gene Association Studies Typically Wrong
« pada: Februari 17, 2007, 04:35:07 PM »
ada yg mau bahas gene-disease association (dan other "omics"-disease association) gak ya? lagi mau ujian nih  :-\

si medaka-kun ke mana nih?


Gene Association Studies Typically Wrong
htp://www.the-scientist.com/2004/12/20/20/1/

...
Trikalinos and other researchers are working to understand why so many studies can't be replicated, and how to change this. The problem is pressing because current trends could exacerbate it, says Sholom Wacholder, senior investigator at the National Institutes of Health biostatistics branch in Bethesda, Md. New high-throughput analysis techniques, he explains, let researchers study many gene-disease associations quickly and cheaply, but also lead to more studies on associations that don't look especially likely at a study's outset. This tends to increase the likelihood of finding spurious links through chance occurrences. By contrast, he says, "In the old days, it was a big investment to study a hypothesis, and only the best candidates had a shot."

Wacholder suggests researchers revise their statistical methods to account for "prior probability," which is a subjective but reasonable measure of how plausible the gene-disease association in question looked before the study.[6] Others propose different solutions. Kirk Lohmueller, a Georgetown University undergraduate student and first author of a letter in Nature Genetics on the subject,[3] suggests bigger sample sizes and more family-based studies. These avoid a confounder called population stratification, the tendency of populations to carry high frequencies of both certain genes and certain diseases owing to mere accidents of ancestry.

"We found that studies with family-based controls and larger sample sizes are more likely to be replicated," Lohmueller says. Trikalinos disagrees that there is any clear way to predict which studies will be replicated. He suggests that researchers should treat any finding cautiously until it's replicated, preferably more than once.

No effort to address the problem is complete, researchers say, without a renewed call to publish more negative findings showing no gene-disease association. Such findings often go unpublished, bolstering false impressions of spurious gene-disease associations. "Every study provides a piece of evidence," says Wacholder, "and it needs to be made available somehow to people who are interested."
...
« Edit Terakhir: Maret 23, 2007, 07:11:19 PM oleh peregrin »
Free software [knowledge] is a matter of liberty, not price. To understand the concept, you should think of 'free' as in 'free speech', not as in 'free beer'. (fsf)

Offline peregrin

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Re: Gene Association Studies Typically Wrong
« Jawab #1 pada: Februari 17, 2007, 04:36:00 PM »
Replication validity of genetic association studies
htp://www.nature.com/ng/journal/v29/n3/abs/ng749.html;jsessionid=A64BB43452B4BDE6B2DECCCBAC7A133F

The rapid growth of human genetics creates countless opportunities
for studies of disease association. Given the number of potentially
identifiable genetic markers and the multitude of clinical
outcomes to which these may be linked, the testing and validation
of statistical hypotheses in genetic epidemiology is a task of
unprecedented scale. Meta-analysis provides a quantitative
approach for combining the results of various studies on the same
topic, and for estimating and explaining their diversity. Here,
we have evaluated by meta-analysis 370 studies addressing 36
genetic associations for various outcomes of disease. We show
that significant between-study heterogeneity (diversity) is frequent,
and that the results of the first study correlate only modestly
with subsequent research on the same association. The first
study often suggests a stronger genetic effect than is found by
subsequent studies. Both bias and genuine population diversity
might explain why early association studies tend to overestimate
the disease protection or predisposition conferred by a genetic
polymorphism. We conclude that a systematic meta-analytic
approach may assist in estimating population-wide effects of
genetic risk factors in human disease.
« Edit Terakhir: Maret 23, 2007, 07:10:59 PM oleh peregrin »

Offline reborn

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Re: Gene Association Studies Typically Wrong
« Jawab #2 pada: Februari 17, 2007, 04:49:36 PM »
Nah lho, peregrin lagi on fire. Abis ngeganja sama mas joko jangan2 ;D
Banyak amat pdf hari ini.... sik asik ;D tapi belum ada yang dibaca sih :(

Wah, ujian kapan? medaka-kun juga lagi ujian kali yah.... Saya bantu dengan doa aja deh yahh  :-X

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Re: Gene Association Studies Typically Wrong
« Jawab #3 pada: Februari 17, 2007, 04:58:36 PM »
bukan on fire, lagi pusing  :) ... butuh teman ngobrol, kalo baca artikel sendiri melulu banyak hal yg cuma masuk kepala keluar lagi   >:(

yaa... admin bantu bacain doong ... itu aja deh, yg tissue engineering, khan pingin tahu juga  :) ... gak sempat juga sih kalo mesti baca sendiri semua, enaknya kalo ada yg gantian ngasih kuliah singkat gitu  ;) (*ini nodong lho  ;D)

ya ada bbrp ujian sampe april ntar ... doain yaa ... kalo doa jarang dipakai katanya sih lebih manjur  ;D hehhehehhe.....

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Re: Gene Association Studies Typically Wrong
« Jawab #4 pada: Februari 17, 2007, 05:23:01 PM »
Waduh, menghina dua kali ini  :'( Lah saya yang pengen nanya2 kok malah disuruh ngasih kuliah.

Terus ini :

ya ada bbrp ujian sampe april ntar ... doain yaa ... kalo doa jarang dipakai katanya sih lebih manjur  ;D hehhehehhe.....

hahaha.... dalem...

Yang tissue engineering belum dibaca, baru mau mulai baca2 nih skrg. Nanti nanya2 boleh yah? LSekalian buat ujian kan ;D Btw, emang ujiannya seperti apa di sana?

 

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