Griscelli syndrome type 1 (GS1) is a rare autosomal recessive disorder that results in pigmentary dilution of the skin and hair, the presence of large clumps of pigment in hair shafts, and an accumulation of melanosomes in melanocytes. In addition to the characteristic silvery-gray appearance of hair and pigmentary defects of skin, GS1 is characterized by primary neurologic deficits that usually are apparent in early infancy and include hypotonia, developmental delay, intellectual disability, and seizures. Immune impairment is not present (summary by Abd Elmaksoud et al., 2020).
Bahadoran et al. (2003) characterized GS1 as comprising hypomelanosis and severe central nervous system dysfunction, corresponding to the 'dilute' phenotype in the mouse, and GS2 as comprising hypomelanosis and lymphohistiocytic hemophagocytosis, corresponding to the 'ashen' phenotype in mouse.
Anikster et al. (2002), Menasche et al. (2002), Huizing et al. (2002), and Bahadoran et al. (2003, 2003) suggested that Elejalde neuroectodermal melanolysosomal syndrome (256710) in some patients and GS1 represent the same entity.
Genetic Heterogeneity of Griscelli Syndrome
Griscelli syndrome type 2 (GS2; 607624), characterized by hypomelanosis with immunologic impairment, is caused by mutation in the RAB27A gene (603868). Griscelli syndrome type 3 (GS3; 609227), characterized by hypomelanosis with no immunologic or neurologic manifestations, is caused by mutation in the melanophilin (MLPH; 606526) gene. [from
OMIM]