Polar lipids of membranes consistently undergo metabolic turnover. The rate of the synthesis is equal to the rate of the breakdown. The breakdown is generally promotedy by hydrolytic enzymes in lysosoms. However, a serious disese can occur if there is an accumulation of the partial breakdown products in the tissue caused by a dfect in the enzymes that is responsible for sphingolipid degradation.
An example of this is the Niemann-Pick disease that is caused by a genetic defect in sphingomyelinase, an enzyme that cleaves phosphocholine from sphingomyelin. Sphingomyelin is found in the brain, spleen, and liver. The disease causes infants to have mental retardation and may result in an early death. Another example is the Tay-Sachs disease, where the body has a lack of enzyme hexosaminidase. The lack of the enzyme causes the build up of ganglioside GM2, which ultimately leads to the Tay-sachs disease. The symptoms of this disease includes progressive retardation in development, paralysis, lindness, and death in three or four years.
A way to detect these diseases is by testing prospective parents and then testing their DNA to determine the exact nature of the defect and the probability it would be passed on to the offspring. If the female is pregnant then doctors would test the cells inside the placenta or the fluid surrounding the baby.
== Reference ==
1. Nelson, David L., Michael M. Cox, and Albert L. Lehninger. "Inherited Human Diseases Resulting from Abnormal Accumulations of Membrane Lipids." Lehninger: Principles of Biochemistry. New York: W. H. Freeman and, 2005. N. pag. Print.