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Difference between Types of Niemann-Pick Disease

There are two main types of Niemann-Pick disease and theseare type A and type B, which are commonly referred to as NPA and NPB,respectively. This disease is actually some sort of an umbrella term used for agroup of specific metabolic diseases which are medically classified aslysosomal storage disorders. Both types of Niemann-Pick disease are triggeredby mutations in a gene located on the chromosome 11. In order to develop thedisease, one needs to inherit two faulty genes, each located on separatechromosomes 11. Such pattern of inheritance is classified as an autosomalrecessive pattern. These gene defects affect a certain enzyme which is referredto as acid sphingomyelinase. This enzyme is in charge of breaking down acertain lipid (a fatty substance) which is known as sphingomyelin. This lipidis one of the main molecules of the cellular membranes. It gets produced in thecell before being transported, used and then recycled in an organelle calledlysosome. This is why this medical condition is referred to as a lysosomalstorage disorder. Other types of lysosomal storage disorders beside theNiemann-Pick disease include the Gaucher’s disorders, the Sandhoff disorder andthe Tay-Sachs disorder. Once the substrate cannot be broken down in the lysosomeit may lead to a vast array of different medical problems. In most cases, thelysosome gradually gets filled up with sphingomyeline and it gets swollen. When this occurs, other substrates cannot be broken down the way they should be. Thebreakdown products are always required for some functions in the cell, and whenthere is a shortage it all has a very detrimental effect on differentoperations in the cell. This medical problem affects all cells alike, so thedeterioration and the failure of entire organs occurs due to the disease. It ultimatelyleads to death. The type A is characterized by clinical effects which commonlyoccur at early stages of life and most children affected by it do not livelonger than 5 years. The biggest problem with Niemann-Pick disease type Ais that it has a rather severe impact on the brain. Type B is much moredifferent, as those who suffer from it may reach adulthood without everexperiencing any related medical problems. The exact cause of such differencesbetween the two types of Niemann-Pick disease is largely unknown. Somemutations may come off as quite aggressive, while some others may not. This iswhy in some cases the breakdown of sphingomyeline still can be carried out at aslightly reduced efficiency rate.

Statistical Data

Fortunately enough, Niemann-Pick type B is considered to bea very rare disease. According to certain estimates it affects one in 5 millionpeople on the Earth. Neurological involvement occurs only in about 10 percent ofall cases of Niemann-Pick type B. Some patients who suffer from Niemann-Picktype B may experience certain respiratory problems, increased levels of badcholesterol in the blood and cardiovascular disease, but those occur only in asmall number of cases. There have also been a few cases of Niemann-pick type Bdisease which involved development of certain bone diseases.

Diagnosis and Treatment Options

The main method of diagnosing Niemann-Pick type B disease isto measure the activity of the acid sphingomyelinase in white blood cells.In most cases, such tests are performed simply by taking a small blood sampleand identifying the person who has two mutated genes. Those who have twomutated genes are diagnosed with the type B disease. Carriers who have only onemutated gene cannot be detected that easily. Carriers can only be detected byutilizing DNA testing. This is mainly due to the fact that the blueprint of theacid sphingomyelinase has been cloned and there are many of its mutationspresent. As far as treatment options go, there are certain new advances inmedical science which could provide all those who suffer from Niemann-Pick typeB disease with new hope. Early diagnosis of the disease can be of great helpin some cases because it may provide sufficient amounts of time required for propermanagement of the disease. Those affected also need some time in order to cometo terms with all the problems which may occur due to the disease. A certaincompany which specializes in lysosomal disorders has already started somestudies which involve the traditional enzyme replacement therapy. Its firstphase is underway and it is soon to be followed by the second one.

Pulmonary Function Tests

Pulmonary function tests for those who suffer from thedreadful Niemann-Pick type B disease involve a group of tests such asspirometry, forced expiratory volume in 1 second and a diffusing capacity oflung for carnon monoxide. Spirometry is commonly performed so that the forcedvital capacity can be assessed.

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