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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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Sturge-Weber & Tuberous Sclerosis
tuberous sclerosis p. 541
tumor suppressor genes and p. 220
Tuberous sclerosis is a genetic condition that causes growths to form in various body organs. Most commonly affecting the brain, skin, kidneys, lungs, and eyes.
Normally, there are two genes called TSC1 and TSC2 that help control the growth and division of cells in the body.
TSC1 encodes the protein hamartin and TSC2 encodes the protein tuberin.
Both of these proteins, are tumor suppressors, meaning they help slow down cell growth and prevent tumors.
They do this by combining to form a hamartin-tuberin protein complex, which binds to and inhibits another protein called mechanistic target of rapamycin, or mTOR.
mTOR activity speeds up the cell cycle and increases cell proliferation mainly thanks to its effect on protein synthesis.
So when mTOR is switched off by the hamartin-tuberin protein complex, it slows growth and division of cells throughout the body.
Individuals with tuberous sclerosis have a mutation in either the gene TSC1 or TSC2, and these mutations have an autosomal dominant inheritance pattern.
The mutations lead to an altered hamartin-tuberin protein complex that’s unable to switch off mTOR.
Because of that, benign tumors and growths called hamartomas form throughout the body.
Hamartomas are kind of like tumors, but they’re made of a variety of cell types from the tissue where they arise, rather than a single cell type.
In fact, if we think of the tissue like a sheet of fabric, a hamartoma is like a knot in the sheet.
Benign tumors and hamartomas can form in any tissue, but the brain and the skin are usually affected the most, along with the kidneys, lungs and eyes.
On top of that the lifetime risk of cancer is increased in individuals with tuberous sclerosis.
That’s because the rapidly dividing cells can develop additional mutations that eventually make these growths expand beyond the basement membrane and invade neighboring tissues.
In the brain, the most common growths are glioneural hamartomas, also known as a cortical tubers. They arise from supportive glial cells as well as neurons.
Next most common are subependymal nodules, which are hamartomas that form under the ependyma, the thin membrane that lines the ventricles in the brain.
Tuberous sclerosis, also known as tuberous sclerosis complex (TSC), is a rare genetic disorder that causes noncancerous tumors to grow in various parts of the body. The condition is caused by mutations in one of two genes, TSC1 or TSC2, which are responsible for regulating cell growth and division.
TSC can affect multiple organs, including the brain, skin, kidneys, heart, and lungs. Symptoms vary widely depending on the location and size of the tumors but may include seizures, intellectual disability, developmental delays, skin lesions, kidney problems, and lung complications.
Diagnosis of TSC typically involves a combination of clinical evaluation, imaging studies, and genetic testing. Treatment may involve a variety of interventions depending on the specific symptoms and organ involvement, such as antiepileptic medications for seizures, surgical removal of tumors, or targeted therapies to block cell growth in affected organs.
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