A mild form of ovine dermatosparaxis

Area of Science:

• Biochemistry
• Genetics
• Veterinary Medicine

Background:

• Dermatosparaxis is an inherited connective tissue disorder.
• It stems from a deficiency in procollagen aminopropeptidase (PAP) activity.
• Previous reports detailed a severe form of dermatosparaxis in sheep.

Purpose of the Study:

• To investigate a milder form of dermatosparaxis in sheep.
• To characterize the molecular defects in affected animals.
• To quantify residual enzyme activity.

Main Methods:

• Analysis of partially processed collagen chains (pN alpha 1, pN alpha 2) using gel electrophoresis and amino acid analysis.
• Assessment of collagenase digestion susceptibility and segment-long-spacing aggregate formations.
• Enzyme assays on skin extracts to measure procollagen aminopropeptidase activity.

Main Results:

• Partially processed pN alpha 1 and pN alpha 2 chains were identified in the skin of affected sheep.
• Fully processed collagen was also detected, suggesting some residual PAP activity.
• Skin extracts from affected animals exhibited approximately 25% of the PAP activity found in normal sheep.

Conclusions:

• This study characterizes a milder form of ovine dermatosparaxis.
• The findings confirm a partial deficiency in procollagen aminopropeptidase activity.
• The presence of both partially and fully processed collagen indicates a spectrum of disease severity.