7-Dehydrocholesterol is a biosynthetic precursor to previtamin D 3 in human skin and to cholesterol in tissues. Although the level of 7-dehydrocholesterol is normally low in human tissues and fluids, it is significantly elevated in a number of human disorders, including Smith Lemli-Opitz syndrome (SLOS) and cerebrotendinous xanthomatosis.
The Smith-Lemli-Opitz syndrome (SLOS) is a common birth defect syndrome characterized biochemically by low plasma cholesterol levels and high concentrations of the cholesterol precursor 7dehydrocholesterol. It is a metabolic and developmental disorder caused by mutations in the gene encoding the enzyme 7-dehydrocholesterol reductase (Dhcr7).
In SLOS, the tissue cholesterol and total sterol levels are markedly reduced while the concentrations of 7-dehydrocholesterol are greatly elevated. This elevation in 7-dehydrocholesterol inhibits the activity of Hmgcr, thus further exacerbating the cholesterol deficit.
Cholesterol in mammals is synthesized from acetate with the final two steps being the conversion of lathosterol to 7-dehydrocholesterol and 7-dehydrocholesterol to cholesterol.
7-Dehydrocholesterol
Vitamins are defined as a group of complex organic compounds present in minute amounts in natural foodstuff that are essential to normal metabolism and lack of which in the diet causes deficiency diseases. Vitamins are required in trace amounts (micrograms to milligrams per day) in the diet for health, growth and reproduction.
Friday, August 17, 2018
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