My brother has myelodysplastic syndromes. should i be worried about this?

Possibly: This would depend upon your brothers age, and his risk factors. For instance if he is elderly, and has significant chemical exposure, than no. If he is young, under the age of 50, mds is uncommon and i would seek a second opinion to confirm the diagnosis. If it turns out to actually be mds than yes, you would be at a higher risk.

Subtypes: There are subtypes. Certain types are more aggressive. There are certain genetic markers which can give you a guide to the prognosis.

Probably not: Myelodysplastic syndrome (mds) in a first degree relative may slightly increase your overall risk but this is still minimal.