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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
Leukodystrophy can be broken down. Leuko- means “white”, -dys means “abnormal” and -troph means “growth”.
So, leukodystrophy means degeneration of the white matter of the brain, and that’s the part of the cerebral cortex that’s filled with myelinated axons.
Myelin refers to the electrical insulation sheath around axons which allows neurons to quickly send electrical impulses to one another.
Leukodystrophy is a dysmyelinating disease, meaning the structure of the myelin is abnormal, and it’s usually due to a genetic mutation.
In contrast, in a demyelinating diseases, previously normal myelin is damaged, like in multiple sclerosis where the immune cells attack the myelin.
There are many different kinds of leukodystrophy, but the most common ones are Krabbe disease, metachromatic leukodystrophy, and adrenoleukodystrophy.
The cerebral cortex is the largest region of the brain and it’s responsible for sensory and motor functions.
The cerebral cortex has an outer grey area and an inner white area.
The grey area, referred to as grey matter, houses neuron cell bodies.
And the white area, referred to as white matter, houses myelinated axons.
It is lighter because of the high fat content in myelin.
Neurons are the key cells that transmit neural impulses to one another through synapses.
Each neuron has dendrites, a cell body, and an axon.
Dendrites are the branches that first receive a neural impulse at a synapse with another neuron.
The neural impulse passes through the cell body and goes through an axon, which projects information away from the cell body to another cell.
Glial cells are support cells for neurons and they produce myelin to coat the axons.
Leukodystrophy refers to a group of dysmyelinating diseases of the central and peripheral nervous system caused by genetic mutations in enzymes necessary for myelin production. The most common types are metachromatic leukodystrophy, Krabbe disease, and adrenoleukodystrophy. Symptoms are due to neurodegeneration, like decreased motor function, muscular rigidity, and later, blindness and hearing loss.
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