6. Developmental and Genetic Disease Flashcards
What disease is known as “Brittle Bone Diseaes”?
Osteogenesis Imperfecta
What structural macromolecule is not synthesized correctly in Osteogenesis Imperfecta?
Type I Collagen
Why do patients with Type I OI appear with blue sclera?
A deficiency in collagen fibers seen in this patient prevents the translucence to the sclera
How do OI patients develop hearing loss?
Fractures and fusion of bones of the middle ear restrict their mobility.
What connective tissue protein is lacking in Marfan syndrome patients?
Fibrillin
What gene mutation is found in patients with epidermolytic hyperkeratosis?
Keratin gene
What is Fibrillin?
Large glycoproteins. They are the most common microfibrils needed for elastin assembly.
What is Anencephaly?
congenital absence of the cranial vault, with cerebral hemispheres either missing or reduced to small masses
During what days of gestation does anencephaly occur/
23rd and 26th
What structures are absent due to failure of the neural tube to close?
calvarium (the dome of the skull), skin and subutaneous tissues
What are 3 major phenotypical charactersitics of anencephaly?
Acrania, protruding eyes, long arms
Neurofibromatosis Type 1 is characterized by what clinical manifestations?
- disfiguring neurofibromas 2 . Areas of dark pigmentation of the skin (care au lai spots) 3. Pigmented lesions of the iris (Lisch nodules)
What is the protein product of the NF1 gene? What is its function?
NF1 geene produces the neurofibomin protien which is expressed in many tissues and belongs to a family of GTPase-activating proteins (GAPs) which inactivate ras protein.. NF1 is a tumor suppressor gene
What is he consequence of loss of GAP activity? What is the predisposition of this abnormality when induced by NF1 gene mutation?
Uncontrolled ras p21 activation; formation of benign neurofibromas
Nf1 is associated with the incidence of what class of tumors?
Neurogentic tumors, (ex. Meningioma, optic glioma, pheochromocytoma)
p21 is active in which form: GTP bound or GDPbound?
GTP (p21 is a membrane bound protein that binds GTPase activating protein from the cytosol)
What protein can be screened for to detect an anencephalic fetus?
Alpha-fetoprotein
What gene mutation is seen in Marfan syndrome patients?
Fibrillin-1 missense mutation
What produces the concentric crings of elastin in the aortic wall/
Deposition of elastin on microfibrillar fibers
What gene mutatikons are found in patients with muscular dystrophy?
Dystrophin
What gene mutatikons are found in patients with OI and Ehlers-Danlos syndrome?
Collagen
Marfan Syndrome follows what pattern of inheritance?
Autosomal Dominant
What unmetabolized substrate is accumulated in Tay-Sachs disease?
Gangliosdies
What molecules are neceesary for Ganglioside metabolism to prevent Tay-Sachs disease development?
Beta-hexosaminidases that require the participation of the GM2-activator protien
Tay-Sachs Disaease follows what pattern of inheritance?
Autosomal Recessive
What are 3 major phenotypical charactersitics of Cystic Fibrosis?
- Chronic Pulmonary Disease 2. Dficient exocrine pancreatic function 3. complications of inspissated mucus in a number of organs including the SI, liver, and reproductive tract
What is a key clinical manifestation in the diagnosis of CF? Describe this pathogenesis.
Increased concentrations of electrolytes in the sweat. This is caused by the decreased chloride conductance that results in a filure of Cl reabsorption by sweat gland cut cells causing NaCL to accumulate in thesweat. Other symptooms will be attributed to the presence of abnormally thick mucus.
CFTR stands for what? What membrane transporter famiily does CFTR belong to?
Cystic Fibrosis Transmembrane Conductance Regulator; ATP-binding familyu of membrane transporter proteins that constitues a chloride channel in most epithelia
Familial Hypercholestoreliam is characterized by deposition of cholesterol where?
arteries, tendons, and skin
What cgene is affected in familial hypercholesterolemia?
Genes that encodes the cell surface receptor that removes LDLs from the blood,LDLR
Due to high levels of Phenylalanine in the first few years of life, what pathology occurs?
Mental deterioration/retardation
Why would a PKU patient have fair skin, blonnd hair, and blue eyes?
the inability to convert phenylalanine to tyrosine leads to reduced melanin synthesis
What causes the “mousy” odor in PKU patients?
phenylacacetic acid formation
PKU is caused by what deficiency? What is the urine product?
Phenylalanine hydroxylase (PAH); Phenylpyruvic acid
Ehlers-Danlos syndromes follow what pattern of inheritance?
Autosomal Dominant
What are phenotype of Ehlers-Danlos syndrome patients?
Hyperelasticity, fragility of the skin, joint hypermobility (unusual extension and flexion), and often a bleeding diathesis