Medically, high blood cholesterol and triglycerides are referred to as lipid disorders. You are said to have high blood cholesterol when you have too many fatty substances in your blood. High cholesterol may be due to genetic causes or, more commonly, due to lifestyle problems such as improper diet, excessive alcohol use, smoking, lack of exercise and certain medications.
Inherited High Cholesterol levels
Inherited high cholesterol levels constitute a condition known as familial hypercholesterolemia. It is an autosomal dominant disorder caused by a defect on the gene 9 of the human chromosome. Because of this, there is formation of defective or no LDL receptors, which results in the liver being unable to remove LDL, or "bad," cholesterol from the blood, thus leading to an abnormally high LDL cholesterol level. Since the defect is autosomal dominant, it means you are likely to get the disease even if one of your parents has it.
Frequency and Types of the Familial Hypercholesterolemia
Familial hypercholesterolemia can manifest in two forms: homozygous and heterozygous. Homozygous occurs when you inherit defective genes from both your parents and heterozygous occurs when you inherit one defective and one normal gene from each of your parents. According to an article published in the journal "Medicine" in March 1966, familial hypercholesterolemia in the homozygous form, has a frequency of 1 case in a million and in the heterozygous form, it increases to up to 1 case in every 500 people in the United States.
Clinical Manifestations of the Types of Familial Hypercholesterolemia
Homozygous hypercholesterolemia is severe and widespread deposit of lipids in all the major arteries and is accompanied by the presence of xanthomas, which are fat nodules under the skin from birth or early childhood. LDL cholesterol levels may be five times higher the normal, reaching 600 mg/dL. Most patients do not survive beyond the age of 30. The main cause of death is heart attacks. Heterozygous hypercholesterolemia is less severe than the homozygous variety. Premature coronary artery disease and high cholesterol levels, up to two times higher than normal are characteristic.
Management of Familial Hypercholesterolemia
Homozygous hypercholesterolemia needs heroic intervention due to uncontrollable coronary artery disease and lack of response to conventional treatments. Treatments under trial are liver transplantation and portacaval anastomoses. Heterozygous hypercholesterolemia can be managed by changes in lifestyle and a low cholesterol diet in combination with cholesterol lowering-drugs like statins.
References
- "Transplantation Proceedings"; Liver transplantation for homozygous familial hypercholesterolemia: two case reports; Kakaei F. et al; September, 2009.
- "Medicine"; Familial Hypercholesterolemia: A Genetic and Metabolic Study; William A. Harlan et al.; March, 1966.
- PubMed Health; Familial Hypercholesterolemia;; May 23, 2010
- PubMed Health; High Blood Cholesterol and Triglycerides; May 25, 2010
