The condition is caused by a loss-of-function mutation. It’s a statement about a protein, not about the whole person.
Edit: ChatGPT explains it better than I can.
The ABCC11 gene encodes an apical efflux pump that helps transport fatty compounds, or lipids, from cells into sweat. When the gene is non-functional, these lipids can’t cross the membrane barrier to reach the armpit. This prevents bacteria from accessing and metabolizing the organic compounds in sweat, which in turn reduces the production of odorant substances.