1. [Gly-X-Y]n ‘R’ US READ Gelehrter et al. pages 143-150
SEE course web pages for related objectives and lecture notes

2. Collagen Disorders Acquired/Multifactorial Aging Mendelian Inheritance
Osteogenesis imperfecta (Type I Collagen)
Ehlers-Danlos syndromes (Types I, II,III, V Collagens)
Chondrodysplasias (Type II Collagen)
Alport syndrome (Type IV Collagen)
Stickler syndrome (Types II, XI Collagen)
Schmid metaphyseal dysplasia (Type X Collagen)
Dystrophic epidermolysis bullosa (Type VII Collagen)

3. Arterial rupture 32 68 60 55 53 30s 1 4 5 36 33 31 5 Aortic dissection
HTN
Splenic
Artery rupture,
Vertebral artery rupture 57,
Aortic dissection 60, 1 4 5 36 33 31
R internal carotid dissection, cerebral infarct,
R vertebral artery aneurysm, s/p repair
Abdominal aorta aneurysm/chronic dissection,
Aneurysm R common iliac 5
Arterial rupture

4. Procollagen
Proelastin
Connective tissue proteins are synthesized in a tissue specific manner by a variety of specialized cells such as fibroblasts, chondrocytes, osteoblasts.

5. What is collagen?
Major extracellular fibrous protein that provides strength and structure to tissues by organizing the extracellular matrix via supramolecular assembly functions
A ropelike structure made by intertwining three polypeptide chains into a triple helix

6. Fibrillar collagens have awesome tensile strength
Reticular collagens provide a meshwork of support

7. 25 distinct collagen molecules vary by content of genetically distinct a-chains
Type I collagen: [a1(I)]2a2(I)
Heterotrimer
two a-1 chains (COLIA1 on chromosome 17)
one a-2 chain (COLIA2 on chromosome 7)
Type III collagen: [a1(III)]3
Homotrimer
two a-1 chains (COL3A1 on chromosome 2)

8. Skin contains Type I, III, V collagens and elastic fibers
Connective tissue supporting hollow organs including colon contains Type III collagen
Connective tissue surrounding blood vessels includes type III collagen and elastic fibers

9. [Gly-X-Y]n Each polypeptide chain is wound in a left-handed helix
X: proline, lysine
Y: hydroxyproline, hydroxylysine.
Each polypeptide chain is wound in a left-handed helix
Three chains form a triple helix monomer
The helix is stabilized by hydrogen bonds in a right-handed helix.
Importantly, the third residue is glycine, as it can fit into the center of the helix.

11. disulfide bonds

15. The making of collagen…
Polypeptide chains are synthesized from ribosomes, signal peptides are removed and a series of post-translational modifications take place:
Intracellular modifications:
Hydroxylation of proline and lysines allows bonding to other molecules which requires co-factors (i.e. vitamin C).
Glycosylation of hydroxylysine residues via galactosyl transferase, lysyl hydroxylase, and glucosyl transferase controls fibrillar morphology.
The three chains align and disulfide bonds form to form triple helix.
Triple helix is packaged into a vesicle and secreted from the cell.
Extracellular modifications:
Calcium dependent N- and C-proteinases remove the propeptides
Procollagen molecules aggregate by a 1/4 staggering in respect to its neighbor and are stabilized by covalent cross links.
A polymeric fibril is formed.
Fibril is arranged in different tissue specific ways

16. By EM (50,000 X), collagen appears as regular striated bundles in longitudinal section and circles on cross section
Type I collagen fibers

17. Some collagens that form long structural fibrils
I. Skin, tendon, bone, dentin; a fetal form also exists
Mutations cause osteogenesis imperfecta, procollagen cleavage mutations cause EDS
II. Cartilage, vitreous humor
Mutations cause abnormalities of skeleton and eye, Stickler syndrome
III. With type I in skin, also in muscles, blood vessels
Mutations cause Vascular EDS
V. Fetal tissues, placenta, interstitial tissues, skin
Important for extracellular matrix assembly, mutations cause classic C Classic EDS

18. Type I collagen
90% of our collagen is type I
two a1(I) chains (COL1A1 chr 17) and one a2(I) chains (COL1A2 chr 7))
Most abundant in: Bones, skin, tendons, cornea
300nm long
1.5nm in diameter
a1(I)
a2(I)
COL1A1 and COL1A2 mutations cause Osteogenesis Imperfecta syndromes
Posttranslational modification defects cause rare Ehlers-Danlos syndromes

19. Type I collagen fibers arranged to provide structural integrity

20. Osteogenesis Imperfecta
Four major clinical sub-types (Sillence classification) vary in phenotypic characteristics and severity (I,IV,III,II)
Highly penetrant, inter- and intra-familial variable expressivity
Prognosis varies greatly depending on type

21. OI Type I (with or without DI)
Most common form
Type I collagen is decreased in amount, generally normal in structure
Normal/near normal height
Little or no bone deformity
Blue/gray sclera
Increased bruising
Joint hypermobility
Possible scoliosis
Possible dentinogenesis imperfecta/opalescent dentin
Conductive hearing loss in up to 50%
Autosomal dominant

22. Osteogenesis Imperfecta
gray/blue sclera

23. Dentinogenesis imperfecta
Opalescent dentin/
Dentinogenesis imperfecta

24. OI Type IV (with or without opalescent dentin)
Osteoporosis and bone fragility without significantly blue/gray sclerae after birth or early onset deafness
25% have fractures at birth while in some cases fractures do not occur until later in life
May be clinically confused with idiopathic juvenile
Short stature
Mild to moderate bone deformities
Scoliosis
Dentinogenesis imperfecta/opalescent dentin in some patients
Possible hearing loss, but not as common as in type I
Autosomal dominant

26. OI Type III Significant fractures at birth and/or infancy
Marked short stature
Severe kyphoscoliosis with progressive platyspondyly
Severe long bone progressive deformities, often require wheelchair
Decreased muscle mass in arms and legs
Loose joints
Whites of the eyes (sclera) have a blue, purple, or gray tint
Brittle teeth
Possible hearing loss
Possible cardiopulmonary problems
Most autosomal dominant,
? Autosomal recessive types
? Additional loci

28. OI Type II Most severe form with extreme bone fragility at birth
Continuous beaded ribs with crumpled long bones
Crumpled long bones with few rib fractures
Narrow, dysplastic beaded ribs with poorly molded long bones and fractures
Frequently lethal at or shortly after birth
Numerous fractures
Severe bone deformities
Very small stature
Underdeveloped lungs
Abnormal brain neuropathology
Diminished and structurally abnormal type I collagen
Most cases autosomal dominant mutations with germline mosaicism

30. Skeletal dysplasia classified according to the region and type of bone involved
Predominantly epiphyseal
Multiple epiphyseal dysplasia
Hereditary arthro-ophthalmopathy (Stickler syndrome)
Chondrodysplasia punctata
Predominantly metaphyseal
Lethal short limb dwarfism
Achondroplasia
Metaphyseal chondrodysplasias
Major involvement of the spine
Spondyloepiphyseal dysplasia ‘congenita’
SED (x-linked and others)
Pseudoachondroplasia
Kneist syndrome
Diastrophic dwarfism
Predominant involvement of single sites
e.g. mesomelic dwarfism
Abnormal bone density and/or modelling defects
e.g. sclerosing disorders of bone
From: Pope FM, Smith R. Color Atlas of Inherited Connective Tissue Disorders, Mosby-Wolfe, 1995

32. OI - Autosomal Dominant
If a child inherits an altered collagen allele, the child will have the same type of OI as the parent
Parent with OI Unaffected Parent
Child with OI
= Normal Gene
= altered Gene

33. ‘Protein suicide’
Normal typical Type I typical type II
okay
degraded

34. How is OI inherited when there is no family history of OI?
5-8% of families without a prior history of OI have multiple children with OI
Due to “new” or “spontaneous” alteration occurs in the gonadal cells which give rise to multiple sperm or eggs.
Germline or gonadal mosaicism - parent not affected by the condition, but mutation in certain percentage of his or her reproductive/germline cells

35. Clinical Testing Diagnostic confirmation of type
Two available tests for OI
Protein/Biochemical
DNA
Prenatal diagnosis available using ultrasound (OI type II), amniocentesis or chorionic villus sampling.

36. How is OI treated? Bisphosphates, calcium, and Vitamin D
Prevent/control symptoms, maximize mobility, and developing optimal bone mass and muscle strength.
Physical therapy, exercise, maintain normal weight
Proper care of fractures
Activity guidance - avoid high risk of injury activities
Pain management
Surgical placement of metal rods in the bones to provide strength
Motility aids, such as wheelchairs and braces
Avoid smoking, excessive alcohol, steroids
Regular dental care
Bisphosphates, calcium, and Vitamin D

37. Ehlers-Danlos Syndrome(s)
1 in 5, ,000 people
both males and females
all racial and ethnic backgrounds

38. Skin:
soft velvety; hyperextensible; fragile - tears or bruises easily; severe parchment paper scars; slow and poor wound healing; molluscoid pseudotumors over pressure areas, striae
Joints:
hypermobile/hyperextensible, loose/unstable; prone to dislocations and/or subluxations; pain; hyperextensible joints; early osteoarthritis; chronic, early onset, debilitating musculoskeletal pain, pes planus, scoliosis
Other:
mitral valve prolapse; blue sclerae, gum disease, organ and vascular fragility

39. Six types of Ehlers-Danlos syndrome
Classic Type (types I and II) AD - Type V and type ? collagen alterations
“Parchment paper” scars, joint hypermobility,skin hyperelasticity, bruising
Hypermobility Type (type III) AD - Type ? collagen alterations
Joint hypermobility/extensibility, joint pain, premature arthritis
Vascular Type (type IV) AD - Type III collagen alterations
Arterial/intestinal/uterine fragility or rupture, bruising, translucent skin
Kyphoscoliosis Type (type VI) AR - Lysyl hydroxylase deficiency
Scoliosis at birth, scleral fragility
Arthrochalasia Type (types VII A, VII B) AD - Type I collagen alterations
Hypotonia, congenital hip dislocation
Dermatosparaxis Type (type VII C) AR - Amino proteinase deficiency
Severe skin fragility, doughy skin, blue sclerae, short stature, severe bruising

40. Diagnostic Criteria for Classic EDS (I and II)
Autosomal Dominant
Major Criteria
Skin hyperextensibility
Widened atrophic scars
Joint hypermobility
Minor Criteria
Smooth, velvety skin
Molluscoid pseudotumors
Subcutaneous spheroids
Joint complications (eg. sprains, dislocations, subluxations, pes planus)
Muscle hypotonia, gross motor delays
Easy bruising
Complications of fragile tissue (hiatal hernia, anal prolapse)
Surgical complications (postoperative hernias)
Positive family history
Laboratory Diagnosis
Type V collagen abnormalities ( < 50%, most unknown)
EM with ‘cauliflower’ fibrils

42. Diagnostic Criteria for Hypermobility Type EDS
Autosomal Dominant
Major Criteria
Generalized joint hypermobility
Skin hyperextensibility OR smooth, velvety skin (if atrophic scars are present, probably classic type)
Minor Criteria
Recurring joint dislocations (frequently shoulder, patella, and TMJ)
Chronic joint/limb pain - often early onset and possibly debilitating
Positive family history
Laboratory Diagnosis
None
Distinguish from familial hypermobility (?)

43. Hypermobility EDS

44. Diagnostic Criteria for Vascular EDS
Autosomal Dominant
Major Criteria: Two major criteria - highly indicative of the diagnosis, One - be very suspicious especially if family history
Thin, translucent skin
Arterial/intestinal/uterine fragility or rupture
Extensive bruising
Characteristic facial appearance with decreased subcutaneous adipose tissue, particularly in face and limbs, often with big eyes, pinched nose
Minor Criteria: One or more minor criteria with positive family history, be suspicious
Acrogeria
Hypermobility of small joints
Tendon and muscle rupture
Talipes equinovarus
Early onset varicose veins
Arteriovenous, carotid-cavernous sinus fistula
Pneumothorax/pneumohemothorax
Gingival recession
Positive family history or vascular or organ rupture, sudden early death in relatives
Laboratory Diagnosis: Type III collagen abnormalities in fibroblasts, COL3A1 mutation

45. Blood dissects along the media (asterisks).
Compressed carotid artery by blood dissecting upward from a dissection.
Blood dissects along the media (asterisks). *
Translucent skin

46. Confirmed by DNA testing 3 16 15 1431
90s
Ruptured renal artery
“Marfan disease” 35 32 43 17
Vertebral aneurysm
Spontaneous pneumothorax
Sigmoidal perforation
Ruptured thoracic artery
Unaffected
Probable EDS IV
EDS IV- Vascular type
Confirmed by DNA testing 3 16 15 14
Bilateral inguinal hernias
Easy bruising
Soft, translucent skin
Increased bleeding

47. Type III Collagen Consists of 3 a1(III) chains (COL3A1 on chr 2)
Thin collagen fibers created
Forms a loosely woven meshwork of reticular fibers
Largely in: skin (with type I and type V collagens)
blood vessels
internal organs (e.g. smooth muscle layers GI tract, uterus, bladder)

48. Vascular EDS Manifestations (Pepin et al, NEJM, 2000)
220 patients, 199 relatives
Mean age at ascertainment: 28.7
Patients: (M , F );
Relatives:
Family history present:
Yes: %
No: 41.4%
Age of first complication in index patients (n=136)
(M , F )
25% had significant complication before 20 years
80% had significant complications before 40 years
Age at death ranged from years, median = 48

49. Vascular EDS Manifestations (Pepin et al, NEJM, 2000)
Type of first complication in index patients

50. Vascular EDS Manifestations (Pepin et al, NEJM, 2000)
Causes of death (n =131)

51. Vascular EDS Manifestations (Pepin et al, NEJM, 2000)
Cause of pregnancy related deaths in 12 of 81 women (167 live births)
Maternal death rate 1 in 23 (11.5%)
Arterial rupture at delivery
Uterine rupture during labor
Arterial rupture in postpartum period

52. Treatment/Management of Vascular EDS
No specific therapies delay onset of complications.
No proven medical surveillance for
complications of Vascular EDS.
The diagnosis should be established to provide genetic counseling, anticipatory guidance and education, and appropriate management strategies for surgeries and pregnancies.

53. Defect in N-Proteinase

54. Diagnostic Criteria for Dermatosparaxis Type EDS
Autosomal recessive
Major Criteria
Severe skin fragility
Sagging redundant skin
Minor Criteria
Soft, doughy skin texture
Easy bruising
Premature rupture of fetal membranes
Large hernias
Laboratory diagnosis
Biochemical confirmation of procollagen N-terminal peptidase (N-proteinase) by analysis of pNa1(I) and pNa2(I) in fibroblasts
Determine level of N-proteinase activity

56. Patient 1 Patient 2 Normal
Dermatosparaxis

57. Genetics of Ehlers-Danlos syndrome
Classic Type (types I and II)
AD - Type V and type ? collagen alterations
Vascular Type (type IV)
AD - Type III collagen alterations
Dermatosparaxis Type (type VII C)
AR - Amino proteinase deficiency

58. Treatment/Management of EDS
Joint care
Skin care
Medications:
Pain medications (avoid excessive NSAIDS in vascular type)
Ascorbic acid (vitamin C) g/day in adults, 0.5 to 1.0 mg/day in children
Consider risks/benefits of anticoagulation in vascular type
Medical and Surgical Care:
Be sure all health care providers know about the diagnosis (medic alert tag)
Obtain emergent care for any new onset of pain and/or neurological systems
Proceed with caution - tissue fragility leads to tears, excessive bleeding
Manage hypertension, avoid constipation, carefully consider risks of pregnancy
Lifestyle:
Avoid contact sports and other high risk activities
Maintain ideal body weight

59. Collagen Disorders - Summary
Collagen - main structural protein in body
Many genetically distinct types of collagen
all have triple helix structure
polypeptide chains with large (Gly -X-Y)n domain
post translational modifications and extracellular processing critical
Type I collagen: Heterotrimer
abundant in skin, bones and ligaments.
mutations in associated genes cause autosomal dominant OI
point mutations in glycine can causing structural collagen abnormality can be more severe than haploinsufficincy (protien suicide)
multiple severely affected children with normal parent can arise due to germline mosaicism
Type III collagen: Homotrimer,
mutations in gene encoding tyope III collagen associated with Vascular EDS (type IV EDS) characterized by vascular and tissue fragility
Many types of EDS but classic EDS usually has skin and joint manifestations