corticobasal syndrome symptomscorticobasal degeneration syndromecorticobasal diseasecorticobasal syndrome mayo clinicmds syndrome prognosismyelodysplasia prognosismyelodysplastic syndrome survival ratecorticobasal degeneration prognosisdown's syndrome informationcarcinoid syndrome prognosiscure for myelodysplastic syndromemyeloproliferative syndromes