Transient myeloproliferative disorder as the presenting feature for mosaic trisomy 21

Area of Science:

• Genetics
• Neonatal Medicine
• Hematology

Background:

• Trisomy 21 (Down syndrome) is associated with congenital conditions, including transient myeloproliferative disorder (TMD) and increased leukemia risk.
• TMD is predominantly observed in hematopoietic cells of neonates with trisomy 21.
• Mosaic trisomy 21 also carries a risk for hematological malignancies.

Observation:

• A nondysmorphic neonate presented with ruddy skin, mild polycythemia, and thrombocytopenia.
• The neonate developed peripheral blasts, indicative of TMD.
• Noninvasive prenatal screening for trisomy 21 was negative.

Findings:

• The neonate's clinical presentation was consistent with transient myeloproliferative disorder.
• Cytogenetic studies confirmed mosaic trisomy 21 in the peripheral blood.

Implications:

• This case underscores the importance of considering trisomy 21, even mosaic forms, in neonates presenting with TMD symptoms, irrespective of prenatal screening results.
• Early identification of mosaic trisomy 21 is crucial for managing associated hematological risks.
• Highlights diagnostic challenges in neonates with congenital disorders and negative prenatal screening.