[Two adult siblings with Chédiak-Higashi syndrome presenting as hyperpigmentation of the skin and the iris].

We report two adult siblings with Chédiak-Higashi syndrome presenting as hyperpigmentation of the skin and the iris. Patient 1 was a 30-year-old man who had generalized hyperpigmentation from one month of age, developed mental deterioration at age 9 years, and gait difficulty at age 20 years. On admission, he showed hyperpigmentation of the skin and the iris without partial albinism. Skin pigmentation was predominated at the face and the extremities. Neurologic examinations revealed mental dysfunction with IQ of 60 by WAIS, cerebellar ataxia, pyramidal signs, extrapyramidal signs, and polyneuropathy. Hematologic examination revealed peroxidase-positive giant granules in leukocytes and decreased activity of natural killer cells, leading to the diagnosis of Chédiak-Higashi syndrome. Patient 2, a younger brother of patient 1, was a 28 year-old man who also had hyperpigmentation of the skin and the iris with similar neurologic findings with patient 1. Both had no episodes of systemic infections. In Japanese cases of Chédiak-Higashi syndrome, more than 50% of them showed hyperpigmentation of the skin from the early stage of the disease. We pointed out that hyperpigmentation of the skin may be a good diagnostic help of Chédiak-Higashi syndrome in Japanese cases.