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March 27, 2004

Genetic priorities

In an earlier post one commenter suggested that focusing on simple genetic diseases is more fruitful than exploring complex polygenic traits & diseases.

1) The causative factor beneath a disease like cystic fibrosis is pretty easy to communicate to the uninterested lay person.
2) Knocking one bird down can basically ameliorate the problem.

But...consider that only 1 in 1500 people of European descent are impacted by cystic fibrosis (1 in 20 are carriers-ie; heterozygous, with one normally functional gene). Compare this to schizophrenia, a disease that affects about ~1% of the human population. The genetic component of schizophrenia is divided between as many as 100 genes.

Unlike CF, there will never be one "smoking gun" that shows the path to defeating schizophrenia, advances will be incremental because genetic causative factors are so numerous. On the other hand, seeing as how as many as 60 million people world-wide might be afflicted, from a utilitarian perspective, one could very well justify advances in relation to large monetary outlays.

Simple dominant-recessive traits are easy to understand for the public theoretically, and practical concerns like greviously debilitating diseases put a human face to the theory. On the other hand, polygenic traits are more difficult to characterize since they are partitioned into many genetic, environmental & gene-environment interaction components. But, the normal distribution of these traits have great social relevance, and increments are worth being pursued. (schizophrenia is a multifactorial "threshold" trait, those who exhibit the disease are at the extreme tail of the distribution)

Aphoristic update: A small good for the many is equivalent to a great good for the few.

Posted by razib at 03:18 PM