NEURODEVELOPMENTAL SIDE-EFFECTS OF BONE-MARROW TRANSPLANTATION - 2 CASE ILLUSTRATIONS OF IDENTICAL-TWINS

Purpose: Bone marrow transplantation (BMT), particularly preparative r egimens, may have a significant impact on the developing nervous syste m. However, the effects of various BMT regimens on children's growth a nd development have been poorly documented to date. Twins serve as ide al subjects to study the impact of medical treatment, since they contr ol for nonmedical (genetic and environmental) influences upon neurodev elopmental outcome. Patients and Methods: Two cases of monozygotic twi ns are presented to illustrate the impact of BMT regimens. Growth data and neurocognitive testing are presented for each patient (affected t win) in relation to his/her syngeneic BMT donor and case control (cont rol twin). Results: These mio cases illustrate the growth retardation that has been reported after BMT. However, changes in growth trends ac ross twins appear to have begun after diagnosis, rather than after BMT per se. Comparisons of cognitive test results within these twin pairs illustrate learning problems in the affected twins. However, there wa s also evidence of learning anomalies in the unaffected twins. Conclus ions: Results underscore the importance of longitudinal assessment in order to identify the side effects of BMT regimens for children. Diffe rences across the two cases highlight important research questions reg arding variables associated with patients, disease, and treatment (e.g ., age at the time of BMT, previous neurotoxic treatments, underlying disease) and emphasize the importance of controls in this line of rese arch.