Bloom's syndrome in a Japanese girl.

Clinical, cytogenetic, and immunological data of a 5-year-old Japanese girl with Bloom's syndrome are described. Growth deficiency, photosensitivity, and a very mild facial telangiectatic erythema were present. Cytological studies revealed chromosomal aberrations and the characteristic high frequency in sister chromatid exchanges. Immunological studies showed that the serum levels of IgM and IgA, but not IgG, were abnormally low as compared to the age-matched control values and that the generation of cytoplasmic immunoglobulin-producing cells in the peripheral blood lymphocytes, which was evaluated in the in vitro pokeweed mitogen-stimulated cultures, was markedly reduced.