What are the genetic changes related to Griscelli syndrome ?
The three types of Griscelli syndrome are caused by mutations in different genes: Type 1 results from mutations in the MYO5A gene, type 2 is caused by mutations in the RAB27A gene, and type 3 results from mutations in the MLPH gene.  The proteins produced from these genes are found in pigment-producing cells called melanocytes. Within these cells, the proteins work together to transport structures called melanosomes. These structures produce a pigment called melanin, which is the substance that gives skin, hair, and eyes their color (pigmentation). Melanosomes are formed near the center of melanocytes, but they must be transported to the outer edge of these cells and then transferred into other types of cells to provide normal pigmentation.  Mutations in any of the three genes, MYO5A, RAB27A, or MLPH, impair the normal transport of melanosomes within melanocytes. As a result, these structures clump near the center of melanocytes, trapping melanin within these cells and preventing normal pigmentation of skin and hair. The clumps of pigment, which can be seen in hair shafts when viewed under a microscope, are a hallmark feature of the condition.  In addition to their roles in melanosome transport, the MYO5A and RAB27A genes have functions elsewhere in the body. Specifically, the protein produced from the MYO5A gene transports materials within nerve cells (neurons) that appear to be critical for cell function. The protein produced from the RAB27A gene is found in immune system cells, where it is involved in the release of certain compounds that kill foreign invaders (such as viruses and bacteria). Mutations in these genes impair these critical cell activities, leading to the neurological problems and immune system abnormalities found in Griscelli syndrome types 1 and 2, respectively.