06-22-2014, 04:48 AM
Lysosomal Storage Diseases
Glycogen Storage Disease II
This disease is characterized by the deficiency of the lysosomal acid alpha-glucosidase enzyme. It is also known by two other names: Pompe disease (named after the Dutch scientist J.C. Pompe who has discovered it in 1932) and acid maltase deficiency (because of the enzyme which can also degrade maltose). It is caused by mutations in gene on chromosome 17. There are around 200 mutations identified up to now that can cause lysosomal storage disease.
Acid alpha-glucosidase degrades glycogen, maltose and isomaltose. If it is mutated and ineffective, glycogen will accumulate in lysosomes and cytoplasm which can lead to cellular injury and may interrupt functioning of organelles.
Based on the levels of alpha glucosidase, there are two forms of Pompe disease:
- Infantile – usually diagnosed within the first 6 months of life. It is characterized by weak muscles and heart failure later on as well as respiratory weakness, which causes death.
- Late onset form – develops more slowly and causes symptoms usually after 2 years of life (or more). It is also characterized by weak muscles and respiratory failure later one. Heart muscles sometimes become enlarged.
Niemann-pick disease
This disease is in the group of sphingolipidosis (subgroup of lysosomal storage diseases) because it is caused by the accumulation of sphingomyelin in lysosomes. There are three forms of it: A, B and C. The first two ones, A and B, are caused by mutations in SMPD1 gene which codes for sphingomyelin phosphodiesterase 1. The third form, type C, is caused by mutations in genes NPC1 or NPC2 (Niemann-pick disease, type 1 and type 2, respectively). These mutations are inherited in autosomal recessive manner, meaning that both alleles have to be defective in order for the disease to be expressed.
Niemann-pick disease affects those organs in which sphingomyelin accumulates. Accumulation in spleen and liver makes them enlarged and may result in pain, thrombocytopenia, etc. Accumulation in central nervous system may lead to ataxia, dysarthria, dysphagia, dementia and seizures. Other parts of the body can be affected, like bones, for example.
Glycogen Storage Disease II
This disease is characterized by the deficiency of the lysosomal acid alpha-glucosidase enzyme. It is also known by two other names: Pompe disease (named after the Dutch scientist J.C. Pompe who has discovered it in 1932) and acid maltase deficiency (because of the enzyme which can also degrade maltose). It is caused by mutations in gene on chromosome 17. There are around 200 mutations identified up to now that can cause lysosomal storage disease.
Acid alpha-glucosidase degrades glycogen, maltose and isomaltose. If it is mutated and ineffective, glycogen will accumulate in lysosomes and cytoplasm which can lead to cellular injury and may interrupt functioning of organelles.
Based on the levels of alpha glucosidase, there are two forms of Pompe disease:
- Infantile – usually diagnosed within the first 6 months of life. It is characterized by weak muscles and heart failure later on as well as respiratory weakness, which causes death.
- Late onset form – develops more slowly and causes symptoms usually after 2 years of life (or more). It is also characterized by weak muscles and respiratory failure later one. Heart muscles sometimes become enlarged.
Niemann-pick disease
This disease is in the group of sphingolipidosis (subgroup of lysosomal storage diseases) because it is caused by the accumulation of sphingomyelin in lysosomes. There are three forms of it: A, B and C. The first two ones, A and B, are caused by mutations in SMPD1 gene which codes for sphingomyelin phosphodiesterase 1. The third form, type C, is caused by mutations in genes NPC1 or NPC2 (Niemann-pick disease, type 1 and type 2, respectively). These mutations are inherited in autosomal recessive manner, meaning that both alleles have to be defective in order for the disease to be expressed.
Niemann-pick disease affects those organs in which sphingomyelin accumulates. Accumulation in spleen and liver makes them enlarged and may result in pain, thrombocytopenia, etc. Accumulation in central nervous system may lead to ataxia, dysarthria, dysphagia, dementia and seizures. Other parts of the body can be affected, like bones, for example.
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