Detection of microsatellite instability in sporadic cardiac myxomas

Microsatellite instability (MIN) is an early event in DNA repair-deficient associated diseases and reflects an elevated mutation rate in the genome of neoplastic cells. Sporadic cardiac myxomas are the most common primary heart tumours and their aetiopathology remains obscure. This study investigates the incidence of MIN in sporadic cardiac myxomas as a possible genetic mechanism of tumour pathogenesis.

Eleven surgically excised sporadic cardiac myxomas were assessed for MI using twenty-two highly polymorphic microsatellite markers, located on a wide range of chromosomal arms. DNA was extracted from myxoma tissue specimens as well as the respective normal tissue and subjected to polymerase chain reaction.

The microsatellite analysis revealed that seven myxoma specimens (64%) exhibited MIN in at least one marker. One tumour specimen exhibited evidence of MIN in four microsatellite markers, while the most frequently affected marker was D17S855 (27%), located on chromosome 17q.

We have detected a considerable incidence of MIN in sporadic cardiac myxomas indicating that decreased fidelity in DNA replication and repair is common in these tumours. To the best of our knowledge this is the first report describing MIN in sporadic cardiac myxomas, as a possible pathogenetic mechanism of these rare neoplasms.