Bloom's syndrome in two Dutch families.

The clinical and cytogenetic data are presented of four children with Bloom's syndrome, who belong to two unrelated Dutch families. The patients showed, in varying degrees, the clinical features most characteristic of the syndrome: stunted growth; telangiectatic facial erythema; sun-sensitivity of the skin; and decreased immuno-competence. In one child the skin lesions were only minor and the diagnosis would probably not have been made if her sib had not been recognized as having Bloom's syndrome. The cytogenetic characteristics of the syndrome were present in all patients. Each showed a high number of chromosomal aberrations and numerous sister-chromatid exchanges per cell.