Ehlers Danlos Syndrome

From Iusmgenetics

Contents 1 Ehlers Danlos Syndrome 1.1 General background information 1.2 Mode of inheritance 1.3 Single important gene 1.4 Etiology 1.5 Pathogenesis 1.6 Phenotypic information 1.7 Diagnosis 1.8 Treatment 1.9 Recent research 1.10 5 important facts 1.11 Not to be confused with 1.12 Questions and answers

[edit] Ehlers Danlos Syndrome

[edit] General background information

• Like Achondroplasia and Osteogenesis imperfecta, a disorder of collagen / connective tissue.
• Like OI, there are a number of different types.
  • Types 1, 4, 6, and 9 are the ones on which we will focus.

[edit] Mode of inheritance

• Type 1: AD (abnormal type 5 collagen)
• Type 4: AD (abnormal type 3 collagen)
• Type 6: AR (decreased crosslinking)
• Type 9: XR (decreased crosslinking)
• As is often the case, recessive conditions reflect a deficiency of some sort.
  • Here there is a deficiency in lysyl hydroxylase (type 6) or copper binding / lysyl oxidase (type 9).

[edit] Single important gene

• Type 1: col5a; abnormal type 5 collagen (abnormal type 5 collagen)
• Type 4: col3a1; abnormal type 3 collagen (homotrimer, mutations in glycines, dominant negative effect)
• Type 6: plod; lysyl hydroxylase deficiency (decreased crosslinking)
• Type 9: mnk; copper binding / lysyl oxidase (decreased crosslinking)

[edit] Etiology

• Type 1: abnormal type 5 collagen
• Type 4: abnormal type 3 collagen
  • homotrimer
  • mutations in glycines
  • dominant negative effect
• Type 6: decreased crosslinking
• Type 9: decreased crosslinking

[edit] Pathogenesis

[edit] Phenotypic information

• Increased elasticity of skin (hyperextensibility).
• Increased fragility.
• Thin skin.
• Abnormal scarring ("cigarette paper" scars).
• Joint laxity (hypermobility).
• Fragility of major arteries
  • May predispose pts to increased surgical risk and / or sudden death.
• Type 4: arteries and colon especially affected

[edit] Diagnosis

[edit] Treatment

[edit] Recent research

[edit] 5 important facts

[edit] Not to be confused with

• Osteogenesis imperfecta
• Achondroplasia
• Marfan syndrome

[edit] Questions and answers