Bulletin Autumn‧Winter 1999

Speedy Decoder of Genet ic Secrets Receives US Patent Company in Silicon Valley Gains License and Agrees to Help Develop Technology New Technolog y f r DNA Sequencin g Prof. Wong Wi n g - h u ng of the Department of Statistics has developed a technology w h i c h g r e a t l y i n c r e a s es t he s p e ed f o r D N A sequencing. The technology has successfully o b t a i n ed a US pa t en t. A n d A f f y m e t r i x, a f a m o u s D N A c h i p m a n u f a c t u r er headquartered in Silicon Valley i n the US, has signed a licensing agreement w i t h the Un i v e r s i ty to use the t e c hno l ogy i n i n d u s t ry i n order to develop products that w i l l f u r t her advance scientific research. What's Hidden in Our DNA Sequences ? D N A sequencing is a basic step i n mu ch of b i ome d i c al research. La r ge amo u n ts of genetic information is encoded i n the D N A of an organism. D N A can be considered as a long p o l y m e r of f o u r t y p e s of n u c l e o t i d es (represented r e s pe c t i v e ly as A , T, G, C i n research) a r r a n g ed i n a p a r t i c u l ar o r de r. H u m a n beings each have about three b i l l i on base pairs of genetic i n f o rma t i on encoded i n our D N A , including v i r t ua l ly the complete set of instructions governing the development of an i n d i v i d u al f r om a single fertilized egg cell to an adult. Mo r eo v er the D N A sequence of any i n d i v i d u al is unique except i n the case of identical twins. Differences i n D N A sequences are the ma i n de t e rmi nan ts of different s k in colours, b o dy shapes, responses to allergens and pathogens, and susceptibility to various diseases. B e i ng able to d e t e r m i ne D N A sequences therefore has enormous implications f o r t he a d v a n c eme nt of l i f e science a n d medicine. How Fast Can We Decode Them? Yet this is easier said than done. A l t h o u gh scientists f o u nd effective methods for D N A sequencing i n the late 70s, those me t hod s, wh i ch studied one D N A clone at a time, were l a b o r i o u s. I t t o ok years to d e t e r m i ne the sequence of a sma ll v i r us w i t h less t h an a hund r ed thousand letters i n its genome. T h e s i t u a t i o n , h o w e v e r , i m p r o v e d s i g n i f i c a n t ly w i t h t he d e v e l o p m e nt of automated sequencing machines i n the late 80s. Current models of automatic sequencers can analyse 96 D N A clones i n a single t wo - hour run, producing up to 60,000 base pairs per run. 10