BS - Connective Tissue Diseases - Week 4 Flashcards
Describe the three components of connective tissue structure.
Cells
ECM
-Fibre
-Ground substance
Name the types of collagen that are fibrillar (5), fibril-associated (1), and sheet-like (1).
Fibrillar - I, II, III, V, XI
Fibril-associated - IX
Sheet-like - IV
Which amino acid is particularly important for collagen and why?
Glycine because it is small and allows triple-helix packing
What kind of helical structure does collagen have, and are its subunits identical?
Is a triple helix of 3 alpha subunits.
They can be identical or distinct:
Homotrimer - identical
Heterotrimer - 2 or 3 different subunits
What 3 systems are most affected by CT disorders?
Musculoskeletal, ocular, and cardiovascular.
Name 2 heritable CT disorders, and what structures they affect.
Stickler syndrome
-Vitreous changes
Marfan syndrome
-Ectopic lens
Name an autoimmune CT disease that affects the sclera.
Scleritis, causing scleral necrosis
Name a CT condition causing high myopia.
Scleral thinning
Distinguish the numeral designation for collagen type and genes.
Type - Roman
Gene - Arabic
A small change to which category of collagen would have the most profound effect?
Fibrillar
What 3 things will an alteration in the amino acid content of a collagen fibre affect?
Structure
Stability
Biological performance
Can changes to the ECM components of collagen affect collagen structure?
Yes, small heritable or environmentally driven changes can affect collagen structure, like lumican (type V)
What effect does altering expression patterns of protein-associated macromolecules have on CT structure and/or function?
Loss of function
Distinguish the following:
Autoimmunity
Hypersensitivity
Immune deficiency
Autoimmunity - failure to distinguish self from non-self
Hypersensitivity - excessive/inappropriate response
Immune deficiency - absent/inadequate response
Describe Sjogren’s syndrome.
T-cell infiltration of the lacrimal gland
Describe the genetic transmission of Stickler syndrome (2).
Autosomal dominant
Autosomal recessive
What three collagen types are targetted by Stickler syndrom, and state its prevalence.
Type II, IX, and XI collagen
Prevalence - 1 : 7,500-9,000
There are 5 subgroups of ocular and systemic manifestations of Stickler syndrome. Describe what each one is caused by, and whether it is ocular or systemic.
Type 1 - ocular and systemic
Type 2 - ocular and systemic
Type 3 - systemic only
Type 4 - ocular and systemic (recessive form)
Ocular only - like type 1, but no systemic manifestations
Name 5 ocular manifestations of Stickler syndrome.
Vitreous abnormalities Retinal degenerations/tears/breaks Cataracts Glaucoma (open angle) High myopia
Name 5 systemic manifestations of Stickler syndrome.
Skull, joint abnormalities
Hearing loss
cleft palate
Heart problems
Name the ocular manifestations for type 1, 2, 3, and 4 forms of stickler syndrome.
Type 1 - sheet-like vitreous opacities or vitreous hypoplasia
Type 2 - beaded-string-like vitreous opacities or vitreous hypoplasia
Type 3 - no ocular phenotype
Type 4 (recessive) - premature vitreous degeneration
Describe the genetic transmission of marfans syndrome and its penetrance.
Autosomal dominant with high penetrance
Name the major ocular complication of marfans syndrome, and three conditions associated with it.
Ectopia lentis
- Flat cornea
- Increased axial length
- Hypoplastic iris or ciliary muscle, causing miosis
Name an ocular manifestation of marfans syndrome and its cause.
Lens displacement - usually superiortemporally, caused by weakened lens zonules due to impaired fibrillin-1
What is scleritis associated with?
An immune-mediated systemic inflammatory condition like rheumatoid arthritis or lupus
Name 7 conditions associated with scleritis.
Thickened sclera Intraocular sequelae Retinal detachment Glaucoma Necrosis Scleral perforation Infection
Name the four types of scleritis.
A - acute
B - nodular
C - necrotising with inflammation
D - necrotising without inflammation
What condition does scleritis often coexist with?
Episcleritis
Describe a symptom episcleritis. Is it associated with another condition like scleitis is?
Causes mild pain without discomfort
Not commonly associated with a systemic disease
Does episcleritis resolve on its own?
Yes, within weeks
Where is the sclera very thin in high myopic eyes?
Posterior pole
Name four functional significances of high myopia.
Reduced tensile strength of the sclera
Major effect at the posterior pole
Causes increased rate of eye growth under normal IOP
Feature of young and myopic eyes
