Method for extracting DNA from dried specimens

Abstract

The present invention relates to a composition and to a method for extracting DNA. More specifically, the present invention relates to a composition and to a method to extract DNA from dried biological samples on solid substrates, including but not limited to, buccal smears, semen and especially blood. The method can be conducted in a single-tube. The DNA extracted in accordance with the present invention can be used for DNA amplification reactions, DNA sequencing, DNA restriction analysis and DNA hyridization.

What is claimed is:  
     
         1 . A composition for extracting DNA from a biological sample which comprises: 
 (a) 5% to 90% formamide;    (b) 5 mM to 60 mM citrate; and    (c) 1 mM to 300 mM buffer, pH 6.0 to 8.8, wherein the buffer is not phosphate.    
     
     
         2 . The composition of  claim 1  which further comprises 0.1% to 50% of a non-ionic detergent.  
     
     
         3 . The composition of  claim 1 , wherein the formamide is present at 5% to 50%.  
     
     
         4 . The composition of  claim 1 , wherein the citrate is present at 10 mM to 40 mM.  
     
     
         5 . The composition of  claim 1 , wherein the buffer is present at 10 mM to 150 mM, pH 7.5 to 8.3.  
     
     
         6 . The composition of  claim 1  which comprises: 
 (a) 10% formamide;  
 (b) 20 mM citrate; and  
 (c) 50 mM buffer, pH 7.8.  
 
     
     
         7 . The composition of  claim 6 , wherein said buffer is Tris.  
     
     
         8 . The composition of  claim 2 , wherein the formamide is present at 5% to 50%.  
     
     
         9 . The composition of  claim 2 , wherein the citrate is present at 10 mM to 40 mM.  
     
     
         10 . The composition of  claim 2 , wherein the buffer is present at 10 mM to 150 mM, pH 7.5 to 8.3.  
     
     
         11 . The composition of  claim 2 , wherein the non-ionic detergent is present at 0.5% to 10%.  
     
     
         12 . The composition of  claim 2  which comprises: 
 (a) 10% formamide;  
 (b) 20 mM citrate;  
 (c) 50 mM buffer, pH 7.8;  
 (d) 1% non-ionic detergent.  
 
     
     
         13 . The composition of  claim 12 , wherein the buffer is Tris.  
     
     
         14 . The composition of  claim 12 , wherein the non-ionic detergent is Tween 80.