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Abnormal lamellar granules in harlequin ichthyosis
M E Milner1, W M O'Guin, K A Holbrook
1Department of Medicine/Dermatology, University of Washington, Seattle.
The Journal of Investigative Dermatology
|December 1, 1992
Summary
Harlequin ichthyosis infants have abnormal lamellar granules that fail to release contents, causing skin scaling. This defect in lamellar granule function underlies the condition, impacting stratum corneum development.
Area of Science:
- Dermatology
- Cell Biology
- Genetics
Background:
- Lamellar granules are vital lipid-rich organelles in epidermal granular cells.
- These granules normally fuse with the cell surface to form intercellular lamellar sheets.
- Previous studies indicated absent or abnormal lamellar granules in harlequin ichthyosis.
Purpose of the Study:
- To investigate the presence and function of lamellar granules in harlequin ichthyosis.
- To characterize the AE17 antigen in relation to lamellar granules.
- To correlate findings with electron microscopy and understand the disease mechanism.
Main Methods:
- Immunoblotting and immunohistochemical analysis using a monoclonal antibody (AE17).
- Analysis of epidermal extracts and skin biopsies from harlequin ichthyosis and normal infants.
- Electron microscopy comparison.
Main Results:
- An immunoreactive protein of 25-28 kD was detected in both normal and harlequin epidermal extracts.
- Normal skin showed apical and intercellular AE17 staining; harlequin skin showed variable apical staining but no intercellular staining.
- Immunohistochemical results correlated with electron microscopy findings of abnormal vesicles and absent intercellular lamellae.
Conclusions:
- Lamellar granules in harlequin ichthyosis contain the AE17 antigen but are structurally abnormal.
- These abnormal granules are defective in discharging lipid and protein contents.
- This lamellar granule defect is proposed as the basis for stratum corneum retention and scaling in harlequin ichthyosis.