Final answer:
A person unable to produce glucagon may experience hypoglycemia as they lack the hormone that raises blood sugar levels during times of need, disrupting the glucose homeostasis maintained by the negative feedback loop.
Step-by-step explanation:
If a person were not able to produce glucagon due to a genetic defect, the likely outcome would be difficulty in maintaining normal blood glucose levels, particularly during times of fasting or low carbohydrate intake. Glucagon is a hormone produced by the alpha cells of the pancreas and plays a critical role in glucose metabolism. It is responsible for stimulating the liver to convert stored glycogen into glucose, which is then released into the bloodstream, thereby raising blood glucose levels. Without glucagon, an individual may experience episodes of hypoglycemia (low blood sugar), since the regulatory mechanism to increase blood glucose levels in response to a drop would be compromised.
Moreover, without the counter-regulatory action of glucagon, insulin's effect on lowering blood sugar may go unchecked, leading to a risk of insulin-induced hypoglycemia. In normal physiology, glucagon and insulin work together in a negative feedback loop to maintain glucose homeostasis. While insulin lowers blood glucose levels by promoting its uptake by cells, glucagon works to prevent blood glucose from dropping too low by promoting glycogen breakdown and glucose release.