Yesterday a Wall Street Journal article defined a word new to me. On the 50th anniversary of the Watson/Crick discovery, it considers why a gene, though associated with a trait, does not produce that trait in every person who caries that gene. Says the author (abbreviated):

quote:

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A nascent revolution called "systems biology" is overthrowing the reductionist, molecular-biology paradigm that has reigned ever since Watson and Crick, and promises to explain why even the most publicized disease genes fall far short of their billing. Of women who carry mutations widely knnow as breast-cancer and ovarian-cancer genes, for example, 56% to 87% get breast cancer and 28% to 44% get ovarian cancer.

The likelihood that a gene will lead to a trait or disease is called its penetrance. Although geneticists and their media enablers give people the impression that DNA is destiny, it isn't so. Systems biology, which abjures the one-gene-at-a-time paradigm to incorporate all the genes and proteins in a cell, may explain why.

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Great word, Shoo. While I hadn't heard it before, it does seem to be where genetic research is now headed. This time, I hope any women involved will get the credit.

I don't recall ever hearing the word before, either, so I looked it up. According to M-W and the OED, date the term, as it applies to genetics, to 1934. (The OED also defines penetrance as "The action of penetrating; penetration", dating from 1642, and labels it"obsolete, rare".)

I found it in a number of on-line genetics dictionaries, including Genome Glossary: "The probability of a gene or genetic trait being expressed. 'Complete' penetrance means the gene or genes for a trait are expressed in all the population who have the genes. 'Incomplete' penetrance means the genetic trait is expressed in only part of the population. The percent penetrance also may change with the age range of the population".

The shortest definition I found was on the The CancerWEB Project (Published at the Dept. of Medical Oncology, University of Newcastle upon Tyne): "The proportion of individuals with a specific genotype who express that character in the phenotype".

Tinman