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Evolution and natural selection
Independent assortment of genes and linkage
Mendelian genetics and punnett squares
Alagille syndrome (NORD)
Familial adenomatous polyposis
Multiple endocrine neoplasia
Polycystic kidney disease
Treacher Collins syndrome
von Hippel-Lindau disease
Gaucher disease (NORD)
Glycogen storage disease type I
Glycogen storage disease type II (NORD)
Glycogen storage disease type III
Glycogen storage disease type IV
Glycogen storage disease type V
Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)
Niemann-Pick disease type C
Niemann-Pick disease types A and B (NORD)
Primary ciliary dyskinesia
Sickle cell disease (NORD)
Tay-Sachs disease (NORD)
Cri du chat syndrome
Fragile X syndrome
Down syndrome (Trisomy 21)
Edwards syndrome (Trisomy 18)
Patau syndrome (Trisomy 13)
Fabry disease (NORD)
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)
Ornithine transcarbamylase deficiency
Autosomal trisomies: Pathology review
Miscellaneous genetic disorders: Pathology review
Muscular dystrophies and mitochondrial myopathies: Pathology review
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mps awareness 2011.wmv
Mucopolysaccharidosis type I, or MPS I, is a rare genetic metabolic disorder caused by deficiency of a lysosomal enzyme required to break down mucopolysaccharides.
The disorder presents as a spectrum ranging from severe forms, classically known as Hurler syndrome, which are associated with life-threatening complications, to attenuated forms, classically known as Scheie syndrome or Hurler-Scheie syndrome.
This disease can cause significant disability but it can also have a near-normal life expectancy.
However, since presentation varies greatly between individuals, these designations are imprecise, so Hurler syndrome is generally used for severely affected individuals and attenuated mucopolysaccharidosis type I is used for all others.
Mucopolysaccharides, also known as glycosaminoglycans, are complex sugars produced by cells and exported to the extracellular space.
They include various molecules including heparan sulfate and dermatan sulfate, and they can be found on almost all cell surfaces as well as in the basement membrane, which separates epithelial cells from the connective tissue underneath.
Mucopolysaccharides are degraded inside the cell, where they’re engulfed by a lysosome, that releases enzymes, which breakdown mucopolysaccharides.
Each mucopolysaccharide requires multiple enzymes to fully degrade, and some mucopolysaccharides are degraded by the same enzymes.
For example, both heparan sulfate and dermatan sulfate need the lysosomal enzymes iduronate sulfatase and alpha-L-iduronidase to be broken down.
MPS I is an autosomal recessive disorder, caused by a variation in the IDUA gene, which results in alpha-L-iduronidase deficiency.
This deficiency prevents heparan sulfate and dermatan sulfate from being degraded, and as a result they build up in various tissues, leading to many complications as well as distinctive facial features, like a prominent forehead, a flat nose bridge, and enlarged lips, tongue, and gums.
MPS I is also classically associated with corneal clouding, where the corneas turns opaque, leading to visual problems and even blindness.
Skeletal malformations like short stature, kyphosis, hip dysplasia, and joint disease are also common, as well as other complications like hernias, respiratory problems, cardiomyopathy, thickened heart valves, hydrocephalus, and neurosensorial hearing loss.
Mucopolysaccharide storage disease type 1 also known as Hurler syndrome, is an inherited disorder caused by a deficiency of the enzyme alpha-L-iduronidase. This enzyme is necessary for breaking down complex molecules called mucopolysaccharides.
When alpha-L-iduronidase is deficient, the mucopolysaccharides are not broken down properly, leading to a buildup of these molecules in the body's cells. This causes a wide range of symptoms, including physical abnormalities, cognitive disabilities, and corneal clouding. Treatment for this condition includes enzyme replacement therapy, bone marrow transplant, and physical and occupational therapy.
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