Expression of fra(10)(q25) in peripheral blood and bone marrow in familial neutropenia.

We report on the expression of fra(10)(q25) in a mother and daughter with familial chronic neutropenia. Differences in expression of the fragile site in bone marrow cells compared with peripheral blood lymphocytes were observed. Short term bone marrow cultures in complete medium showed high levels of spontaneous expression, whereas in 72 hour stimulated blood cultures it was virtually absent. There were also differences in the types of lesions found; chromosome type lesions predominated in the marrow and chromatid type in the blood. Apparent folate sensitivity of the fra(10)(q25) is also discussed.