Lysosomal-Storage Disorders (LSDs):
The clinical presentation of LSDs depends on the type, quantity and site of storage of undegraded material. However, there are a number of overlapping clinical features that are not specific for LSDs, which can make the diagnosis very challenging. The diagnosis for LSDs is established by specific enzyme assays, through urine analysis for specific undegraded macromolecules, as well as mutational analysis. Prenatal diagnosis is possible for all lysosomal storage disorders.
Griscelli Syndrome (GS):
The diagnosis of GS is usually supported by the microscopy examination of the hair shaft. The characteristic neurological symptoms and analysis of lymphocyte cytotoxic activity of patients tend to descriminate the molecular causes. Confirmation can be provided by mutation analysis of the patient’s DNA. Direct mutation-based carrier detection and prenatal diagnosis are possible in families with defined gene mutations.
Hermansky-Pudlak Syndrome (HPS):
HPS is diagnosed through clinical features, such as hypopigmentation of the skin and hair, characteristic eye findings and appearance of platelets by electron microscopy. Molecular genetic testing for mutations in the HPS1, AP3B1, HPS3, HPS4, HPS5, HPS6, DTNBP1, BLOC1S3, PLDN and AP3D1 genes is available to confirm the diagnosis.
The patient’s visual field is examined and checked for degeneration of the retina. A blood test that detects all CHM mutations is available, although a precise diagnosis depends on DNA sequencing.