DNA from formalin preserved tissue

uks13mh uks13mh at fub46.zedat.fu-berlin.de
Wed Nov 2 16:57:29 EST 1994

In article <CxwxF6.6u at news.Hawaii.Edu>, duda at uhunix2.uhcc.Hawaii.Edu (Thomas F Duda) says:
>I am currently trying to extract (and amplify) DNA from tissue
>originally fixed in formalin (actual length of time in formalin is 
>unknown) and then kept in ethanol (age of samples ranges from 25-35
>years).  SO far I have not tried anything beyond a proteinase K/phenol/
>chloroform extraction that typically yields spooled DNA from fresh
>or recent, ethanol-only-preserved tissue.  DTT has been suggested as
>a means of breaking up the DNA-protein cross-links, so this may be the
>next line of attack.  ANy suggestions or advice would be appreciated. 
>Has anyone had luck with formalin-preserved tissues or am I wasting
>my time?
>        +========================================+
>        +               Thomas F. Duda, Jr.      +
>        +       duda at uhunix.uhcc.hawaii.edu      +
>        +========================================+
Hi Thomas

I am working with formalin-fixed paraffin-embedded samples 
since more than 6 years. In principle it works. 
But there are some limitations. 
First of all the time of formalin-fixation is crucial. 
Tissue sample fixed for more than one week are often not 
suitable to release DNA for PCR. In addition, the length 
of the amplificates is very important. Amplificates of 
more 400 bp could often not be generated in routinely fixed 
material. Another issue is the type of fixation. 
Fixation in un-buffered formalin prevents the subsequent 
PCR very efficiently!!
Best wishes
Michael Hummel
UKS13MH at fub46.zedat.fu-berlin.de
Inst. of Pathology
Free University Berlin

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