Griscelli syndrome is a rare, sometimes fatal disorder that associates partial albinism with immunodeficiency. Partial albinism is characterized by a partial lack of melanin (pigment) in the eyes, hair, and skin. The partial albinism found in patients with Griscelli syndrome is caused by an abnormal melanosome distribution. Immunodeficiency refers to an immune system in which restance to infection is lowered.
In addition to having silvery hair, most people with Griscelli syndrome develop hemophagocytic syndrome, which causes some blood cells in the body to engulf and destroy other blood cells. Hemophagocytic syndrome leads to death unless the patient undergoes a bone marrow transplant.
Some people with Griscelli syndrome are severely impaired neurologically but have no apparent immune abnormalities. Neurologic problems may be spasticity (in which a patient has uncontrolled muscular contractions), rigidity (in which a patient is inflexible or stiff), and convulsions. Through 1994 only 19 patients were reported in the medical literature as having the disorder.
Griscelli syndrome is an autosomal recessive disorder that sometimes occurs in children with parents who are related by blood. There is evidence that the disorder is caused by mutations in the gene that encodes myosin VA, a protein in muscle tissue. (The gene encoding myosin VA is MYO5A.) The gene associated with Griscelli syndrome has been mapped to the long end of chromosome 15 at location 15q21. A second gene, RAB27A, maps very close to the same region (15q21) as MYO5A.
Both males and females are born with Griscelli syndrome.
Signs and symptoms
Griscelli syndrome causes pigmentary dilution of the skin and hair, and clumps of pigment in hair shafts. Griscelli syndrome also causes an accumulation of melanosomes in melanocytes.
People with Griscelli syndrome may also have frequent infections in which pus is present, fever, an abnormal decrease in the number of white blood cells, and a reduction in the number of platelets in the blood.
Griscelli syndrome can be diagnosed in fetuses in the womb by microscopically examining the hair shaft. After birth, patients are diagnosed with Griscelli syndrome based on the signs and symptoms.
Griscelli syndrome is similar to Chediak-Higashi syndrome. For example, both are autosomal recessive disorders in which partial albinism and immunodeficiency are associated. And patients with either disorder are likely to have frequent infections.
However, patients with Chediak-Higashi syndrome are likely to have giant granules in their leukocytes, a type of white blood cell. And leukocyte-specific protease activity is typically low in patients with Chediak-Higashi sydrome, and typically normal in patients with Griscelli syndrome.
Treatment and management
In patients who have hemophagocytic syndrome associated with Gricselli syndrome, treatment may be in the form of bone marrow transplantation.
The prognosis for babies with Griscelli syndrome is poor without bone marrow transplantation.
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"Griscelli Syndrome." Online Mendelian Inheritance in Man. <www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=214450>.