Smell Like A Fish

by Jonathan Hodgkin

WHEN A GENE MAKES YOU SMELL LIKE A FISH. And other tales about the genes in your body. By Lisa Seachrist Chiu. 219pp. Oxford University Press. Pounds
15.99. (US $27). 0 19 516994 8

Body odour is part of being human. We are all smelly to some degree, but some of us are smellier than others. In extreme, and fortunately very rare cases, a person may suffer from a pathological condition that causes them to emit a fish-like stench, with catastrophic effects on their interactions with other people. Lisa Seachrist Chiu takes this condition, called fish odour syndrome or, more technically, trimethylaminuria (TMAU), as the starting point of a tour of notable human genes. TMAU is a good place to start, because it is a straightforward example of a disease caused by mutation in a single gene, which encodes an enzyme called FMO3. What FMO3 does is to break down one of the by-products of normal food digestion, trimethylamine, which is a nauseatingly fishy compound; so if someone is deficient in FMO3 production, they accumulate trimethylamine and become incurably smelly.
Chiu goes on to describe an assortment of other human genetic diseases, ranging from well-known, single-gene abnormalities like phenylketonuria, Huntingdon's disease and haemophilia, to more complex disorders involving multiple genes and environmental factors, as well as complications such as imprinting and X chromosome inactivation. She ends with a chapter on molecular studies of human evolution and development, and a brief epilogue on single nucleotide polymorphisms and their potential for a new revolution in medicine.
This survey of human genetics, written for a general audience, is readable and sometimes engaging, but it is carelessly written and inconsistent in the level of explanation used. Technical terms are introduced before being adequately explained, and several of the stories are left dangling unsatisfactorily, or ended with a laboured pun. Chiu also misses some key points -for example, she writes about the discovery of FOX2P, the first candidate for a "gene for language", but fails to mention one of its most exciting and suggestive properties, namely its remarkably rapid evolution. Better books of this type have been written, such as Matt Ridley's Genome (1999) and Armand Leroi's Mutants (2003). When a Gene Makes You Smell Like a Fish has the advantage of being reasonably up to date, but otherwise there is not much to recommend it.