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Study of Chediak-Higashi Syndrome

2014-08-27 03:57:37 | BioPortfolio

Summary

This study will investigate the underlying cause of Chediak-Higashi syndrome (CHS)-a rare inherited disease-and define the full spectrum of medical complications associated with it. It will study the LYST gene - the gene responsible for classic CHS-and investigate other genes that may cause milder forms of the syndrome.

Patients with CHS have a range of medical problems, including decreased pigment in the skin and eyes, a tendency toward bleeding because of a platelet dysfunction and recurrent infections due to white cell abnormalities. Some patients also have neurologic problems, such as poor sensation in the arms and legs. The only cure for CHS is bone marrow transplantation, but other measures can be taken, such as avoiding aspirin to prevent bleeding episodes.

Patients one month or older with decreased pigmentation and either a bleeding abnormality or history of excessive childhood infections may be eligible for this study, which is expected to continue for 5 to 10 years. Participants will be admitted to the NIH Clinical Center for about 5 days every 1 to 3 years, depending on the severity of their conditions, for the following procedures:

1. Medical history, physical examination, complete eye examination and consultations with infectious disease and neurology specialists

2. Blood tests, including routine tests, such as complete blood count, blood chemistries, etc.; tests to look for giant granules and platelet dense bodies; tests to examine white blood cell function; and tests to analyze DNA of the LYST gene

3. 24-hour urine collection to assess kidney function

4. Skin biopsy to study cells called fibroblasts, in which an area of skin is numbed with an anesthetic and a circular area 4 mm in diameter is then removed using a sharp punch and scissors. The wound is then dressed; healing time is usually within a week.

5. Visual evoked response test, in which small electrodes are applied to the scalp (similar to an electroencephalogram). The patient looks at a screen with changing patterns and at flashes of light while the electrical activity of the brain is recorded.

Depending on the individual patient's condition, consultations may also be arranged with hematology (blood), dermatology (skin) and pulmonology (lungs). Additional tests may include X-rays, computerized tomography (CT) or magnetic resonance imaging (MRI) of the head, pulmonary function tests to measure breathing capacity, and photographs of the face and body taken with underwear on.

Description

Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disorder characterized in its classical form by oculocutaneous albinism, a bleeding diathesis, recurrent infection due to abnormal neutrophil and natural killer cell function, and eventual progression to a lymphohistiocytic infiltration known as the "accelerated phase". Death often occurs within the first decade as a result of bleeding, infection, or development of the accelerated phase; bone marrow transplantation is curative except for the late occurrence of neurological deterioration. The basic defect is unknown, although it probably involves abnormal fusion or trafficking of intracellular vesicles. Patients with classical CHS have their disease due to mutations in the LYST gene, but mildly affected individuals have been reported whose genetic defect has not been defined. It is likely that these variants of CHS have abnormalities in proteins involved in the pathways responsible for vesicle fusion. Since the full clinical spectrum of CHS and its variants has not been characterized, and the underlying defects remain enigmatic, we plan to evaluate this group of patients clinically, biochemically, and molecularly, and perform cell biological studies on their fibroblasts, melanocytes, and transformed lymphoblasts. Routine admissions will be 5 days and occur every two years.

Study Design

N/A

Conditions

Chediak Higashi Syndrome

Location

National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda
Maryland
United States
20892

Status

Recruiting

Source

National Institutes of Health Clinical Center (CC)

Results (where available)

View Results

Links

Published on BioPortfolio: 2014-08-27T03:57:37-0400

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