AMYLOIDOSIS

1. What is amyloidosis
• Amyloidosis is the term used for a group of diseases characterised by
extracellular deposition of fibrillar insoluble proteinaceous substance
called amyloid having common morphological appearance, staining
properties and physical structure but with variable protein (or bio
chemical) composition.
• It is derived from the word-amylum in Latin, amylon in Greek; means
cellulose or starch like. ◎Definition : Amyloid refers to an abnormal
deposit of insoluble polymeric protein fibrils in tissues and organs.
This condition of deposition of amyloid in tissues is known as
Amyloidosis.
• First described by Rokitansky in 1842, the substance was
subsequently named by Virchow as ‘amyloid’

2. Chemical structure of amyloid
• Ultra structural examination and chemical analysis reveal the
complex nature of amyloid.
• On the basis of morphology and physical characteristics, all
forms of amyloid are similar in appearance, but they are
chemically heterogeneous.
• Based on analysis, amyloid is com posed of 2 main types of
complex proteins
I. Fibril proteins comprise about 95% of amyloid.
II. Non-fibrillar components which together constitute the
remaining 5% of amyloid.

3. • The fibrillar amyloid can be categorised as under:
i) AL (amyloid light chain) protein
ii) AA (amyloid associated) protein
iii) Other proteins

4. Pathogenesis of amyloidosis
• The earliest observation that amyloidosis developed in experimental
animals who were injected repeatedly with antigen to raise antisera for
human use led to the concept that amyloidogenesis was the result of
immunologic mechanisms.
• Thus, AL variety of amyloid protein was isolated first. It is now
appreciated that amyloidosis or fibrillogenesis is multifactorial and
that different mechanisms are involved in various types of amyloid.

5. • Amyloidosis results from abnormal folding of proteins, which become
insoluble, aggregate, and deposit as fibrils in extracellular tissue.
• Normally, misfolded proteins are degraded intracellularly by
proteasomes or extracellularly by macrophages.
• In amyloidosis this quality control mechanism fails so,
• There is rise in level of precursor of fibrillary protein followed by
partial degradation by reticuloendothelial cells.
• Non-fibrillary proteins facilitate aggregation and protection against
solubilisation.
• So all these factors result in deposition of misfolded protein outside
the cells.

6. CLINICAL FEATURES
• Clinical features • May produce no clinical manifestations or may
cause serious problems & even death. • At first features are non
specific like weakness, weight loss, light headedness or syncope.
• Liver-hepatomegaly, ↑ alkaline phosphatase. • Spleen-splenomegaly
& splenic dysfunction. • Heart-congestive heart failure, restrictive
cardiomyopathy, constrictive pericarditis & amyloid deposits in valves.
• KIDNEYS stage phase course initial Proteinuria Slowly progressing
Clinical manifestations Nephrotic syndrome Oedema,proteinuria
Hypertensive (rare) Rapidly progressing terminal course Chronic renal
failure Relapsing

7. • Central Nervous System Dementia(Alzheimers disease) Hemorrhagic
strokes • Peripheral nervous system Peripheral neuropathy
• Endocrine organs hypothyroidism due to infiltration.
• Musculoskeletal "Shoulder pad sign" - enlargement of the anterior
shoulder due to amyloid deposition in periarticular soft tissue eg-
Carpal tunnel syndrome.
• Blood vessels - Increase susceptibility to bruising-typical Raccoon
eyes
• • Gastrointestinal amyloidosis- macrglossia which may hamper
speech.
• In stomach and intestine may lead to malabsorption

8. Types of amyloidosis and the clinical
condition associated with it.

9. ALL THE VERY BEST TO
MY DEAR STUDENTS