Griscelli syndrome is an autosomal recessively inherited disease characterised by reduced pigmentation of the skin and hair (hypomelanosis), the presence of large
clumps of pigment in hair shafts. In Griscelli syndrome melanosomes accumulates in
melanocytes. Disorders of the immune system are not always present: some patients develop neurologic signs without immunological involvement, while some others develop a hemophagocytic syndrome that requires bone marrow transplantation. Patients present with partial albinism with characteristic silver-grey hair. Patients with mutations in MYO5A (Griscelli syndrome type 1, GS1) develop neurological but no immunologic problems, whereas patients with mutations in RAB27A (Griscelli syndrome type 2, GS2) develop immunologic abnormalities with or without neurologic impairment. A third form of Griscelli syndrome (GS3) is limited to hypopigmentation: mutations occur in the MLPH gene. Also GS3 is autosomal recessive, like the other two. As the three different types present important differences in treatment options and prognosis, molecular testing is pivotal for Griscelly syndrome patients.
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