Hypolipoproteinemia refers to unusually low levels of fats (lipids) in the blood. Low lipid levels may be caused by rare genetic conditions, or be a sign of another disorder such as overactive thyroid, anemia, undernutrition, cancer, chronic infection, or impaired absorption of foods from the digestive tract. Associated genetic disorders includes abetalipoproteinemia, familial hypobetalipoproteinemia, and chylomicron retention disease. Signs and symptoms in the the genetic or familial form of Hypolipoproteinemia vary. In some forms, although the low density lipoprotein (LDL) cholesterol levels are very low, this syndrome may not cause any symptoms. Other forms result in absent or near absent LDL levels and can cause symptoms in infancy and early childhood.