Author: Dr Harriet Cheng, Dermatology Registrar, Greenlane Hospital, Auckland. Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, June 2014.
Hermanksy-Pudlak syndrome is an inherited disorder due to an abnormality of lysosome-related organelles. Nine subtypes are described. It is characterised by:
Lysosomes are organelles (structures found within cells) that contain substances capable of breaking down various structures such as proteins, lipids, carbohydrates and nucleic acids (components of DNA).
Lysosome-related organelles are structures found within specific types of cells (eg melanocytes) that share some similarities with lysosomes. They have various functions, including involvement in processes of pigmentation, blood clotting and immunity.
Cutaneous findings in Hermansky-Pudlak syndrome include:
Visual disorders in Hermanksy-Pudlak syndrome include:
Systemic conditions associated with Hermansky-Pudlak syndrome include:
Hermansky-Pudlak syndrome is inherited. The pattern of inheritance is autosomal recessive, so the parents of affected children rarely have the disease themselves. Each parent carries at least one copy of the disease gene. If each parent is a carrier, the chance of their offspring having Hermasnky-Pudlak syndrome is 1 in 4.
Presently (2014), at least 7 different genes causing Hermansky-Pudlak syndrome have been identified. Affected genes (BLOC genes) encode components of the biogenesis of lysosomal organelles complexes.
The diagnosis of Hermansky-Pudlak syndrome may be suspected on clinical grounds when a child presents with unexpectedly light-coloured hair, skin and eyes associated with a tendency to bleeding. Electron microscopy of platelets demonstrates virtual absence of dense bodies, which are required for normal platelet aggregation. Genetic linkage studies may identify the underlying mutation.
As this syndrome is the result of a defective gene no curative treatment is possible.
Important management considerations include:
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