Study of Blood Samples From Newborns With Down Syndrome

Inclusion Criteria:

   - Diagnosis of transient myeloproliferative disorder (TMD) at < 90 days of age and
   meeting 1 of the following criteria:

      - A diagnosis of Down syndrome or Down syndrome mosaicism AND non-erythroid and
      non-lymphoid blasts (any amount) in the peripheral blood verified with a second
      sample

         - Patients with typical physical characteristics of Down syndrome are allowed
         before cytogenetic or FISH confirmation of the diagnosis

      - Trisomy 21-positive leukemic blasts documented by biopsy of any organ (including
      > 5% non-erythroid/non-lymphoid blasts documented by bone marrow aspirate or
      biopsy)

         - Infants with isolated trisomy 21 positivity identified only in the leukemic
         blasts are allowed

   - Institutional immunophenotype characterization is required for study enrollment