MOLECULAR ANALYSIS OF MEDULLOBLASTOMAS OCCURRING SIMULTANEOUSLY IN MONOZYGOTIC TWINS

We report male monocygotic twins with concordant desmoplastic medullob lastoma diagnosed al the age of 20 months, Both tumours were completel y removed. As chromosomal loci 17p13 and 9q31 are frequently altered i n medulloblastoma these regions were analysed in both tumours in detai l using restriction fragment length polymorphism and microsatellite an alysis. No common aberration was found. The c-myc gene on chromosome 8 q21 was not amplified. Conclusion Although a common genetic defect has not been found in our patients' tumours the clinical presentation sup ports the assumption of an inherited genetic predisposition to develop medulloblastoma in at least some cases.