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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
Niemann-Pick disease type C, or NPC, is a rare genetically inherited condition caused by mutations in either the NPC1 or NPC2 genes.
These mutations impair intracellular transport of cholesterol and other molecules, which causes progressive neurologic and developmental problems.
Now, cholesterol reaches the cells packed in lipoproteins, which bind to low density lipoprotein, or LDL, receptors on the cell membrane, to get inside the cell.
Then, cholesterol reaches the early-endosome, which is an intracellular organelle that eventually matures into a late-endosome, and finally into a lysosome.
Inside the lysosome, cholesterol is processed and recycled, so that it can be incorporated into the cell membrane.
To get out of the lysosome, first, cholesterol gets a little help from the NPC2 gene product, a protein that carries cholesterol up to the lysosomal membrane.
And on this membrane, cholesterol is greeted by the NPC1 gene product, which is a glycoprotein that moves cholesterol out of the lysosome and into the cell.
So with NPC1 or NPC2 mutations, intracellular cholesterol transport is impaired, so cholesterol accumulates inside lysosomes instead. Mutations can affect people of all ethnic backgrounds, and they’re inherited in an autosomal recessive pattern, which means that an affected individual must have two copies of the mutated gene, one from each parent.
Cholesterol buildup affects almost all cells, so it causes a variety of symptoms.
The brain and bone marrow are often affected.
The liver and spleen can be affected too, in which case, they enlarge.
Liver enlargement disrupts bile flow, causing bilirubin to accumulate in the blood.
This leads to jaundice, or yellow pigmentation of the skin and whites of the eye.
An enlarged spleen, on the other hand, may trap platelets, which causes easy bruising and bleeding issues.
Niemann-Pick disease type C is a rare genetically inherited condition, caused by mutations in the NPC1 or NPC2 genes. These mutations impair intracellular transport of cholesterol and other molecules, which causes progressive neurologic and developmental problems. This causes cholesterol to accumulate in lysosomes, resulting in brain, bone marrow, liver, spleen and lung damage.
Symptoms of Niemann-Pick disease type C typically begin in childhood and may include difficulty with movement and balance, difficulty swallowing, developmental delays, and progressive intellectual disability. There may also be hepatosplenomegaly, and liver failure.
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