Question: What is (are) Hypolipoproteinemia ?
Answer: 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, hypobetalipoproteinemia, and chylomicron retention disease. Symptoms of the genetic or familial form of hypolipoproteinemia varies. In hypobetalipoproteinemia the low density lipoprotein (LDL) cholesterol levels are very low, yet people with this syndrome typically have no symptoms nor require treatment. Other forms result in absent or near absent LDL levels and can cause serious symptoms in infancy and early childhood.
Source: GARD

Question: What are the symptoms of Hypolipoproteinemia ?
Answer: Are there other symptoms associated with hypolipoproteinemia? Some reports suggest that hypolipoproteinemia (low cholesterol levels) in general may increase the risk for development of fatty livers.
Source: GARD

Question: What causes Hypolipoproteinemia ?
Answer: What causes familial or genetic hypolipoproteinemia? Cholesterol levels in general are thought to be influenced by genetic factors. Very low levels of lipids (hypolipoproteinemia) is known to be caused by certain genetic conditions, including hypobetalipoproteinemia, abetalipoproteinemia, and chylomicron retention disease. Hypobetalipoproteinemia is inherited in an autosomal dominant fashion. Autosomal dominant inheritance is when one mutated copy of the gene that causes a disorder in each cell is needed for a person to be affected. Each affected person usually has one affected parent. Autosomal dominant disorders tend to occur in every generation of an affected family. When a person with an autosomal dominant disorder has a child, there is a 50% chance that their child will inherit the condition. In some families the condition is due to mutations in a gene called APOB, in other families the underlying mutation has not been identified. People with this condition usually do not experience symptoms. People who inherit two hypobetalipoproteinemia gene mutations may have extremely low levels of low-density lipoprotein cholesterol (LDL-C) and apolipoprotein B (apoB). Some of these individuals have no symptoms while others have developed fatty liver, intestinal fat malabsorption, and neurological problems. Abetalipoproteinemia is a rare disorder with approximately 100 cases described worldwide. Mutations in the MTTP gene cause abetalipoproteinemia. It is passed through families in an autosomal recessive pattern. Click here to learn more about autosomal recessive inheritance. The signs and symptoms of abetalipoproteinemia may include failure to thrive, diarrhea, abnormal star-shaped red blood cells, and fatty, foul-smelling stools in infants, nervous system impairment in children, retinitis pigmentosa and difficulty with balance and walking in childhood or adulthood. Chylomicron retention disease is a rare condition with approximately 40 cases described worldwide and is also inherited in an autosomal recessive pattern. The signs and symptoms appear in the first few months of life and may include failure to thrive, diarrhea, fatty, foul-smelling stools, and later nervous system impairment. Other genetic conditions characterized by hypolipoproteinemia include, but is not limited to: Lecithin acyltransferase deficiency Tangier Disease
Source: GARD