Hi Idonald,
Your mother has a type of MDS that is very uncommon.
http://www.ncbi.nlm.nih.gov/pubmed/21350094
Her spleen enlargement is maybe a symptom of the disease Myelofibrosis. Patients with Myelofibrosis can have positive effect when they are treated with the JAK2 inhibitor Jakafi, that is approved for Myelofibrosis. Hope the drug will help your mother.
Kind regards
Birgitta-A