Conditions with abnormally low levels of lipoproteins in the blood. This may involve any of the lipoprotein subclasses, including alpha-lipoproteins (high-density lipoproteins); beta-lipoproteins (low-density lipoproteins); and prebeta-lipoproteins (very-low-density lipoproteins). The disease is Monarch Disease Ontology id MONDO_0001822 (hypolipoproteinemia). Also known as: hypolipoproteinaemia, hypolipoproteinemia (disease).