This is a big pet peeve. Let’s get straight to business: the terms “homeobox” and “Hox” are not interchangeable. They do mean different things. I’m correct in saying that Amphioxus (Branchiostoma lanceolatum) has 15 Hox genes. I’m also correct in pointing out that it has over 130 homeobox genes.
Gene names can be very confusing and difficult to remember, so there are many abbreviations in biology. For example, the gene insulin-like growth factor 1 is abbreviated to Igf1. Does that make it easier to remember? Who knows. But I believe the use of abbreviations is partly responsible for the incredible confusion over homeobox and Hox genes. And I do mean incredible. It’s very obviously a confusing topic for students, or anyone new to evo-devo, developmental genetics, or gene regulation… but it’s so much worse than that. Professional publications make the mistake, academics make the mistake, and they do it often. I think the reason it keeps happening is that the word “Hox” appears to be a shortened “Homeobox”. All over the internet you will see the terms used interchangeably, and sometimes with the apparently shortened version in brackets. “Homeobox (Hox)”. This otherwise decent glossary for Epigenesys manages to dump the terms homeotic, homeobox, and Hox into one single paragraph and glossary entry, which is of little help to a confused student seeking clarity. So let’s clear this up, and I’ll keep it quick. Continue reading The difference between homeobox and Hox genes