Work

Noonan Syndrome Presenting With Severe Transient Thrombocytopenia and Hemolytic Anemia in a Neonate With a Germline PTPN11 Pathogenic Variant

Year: 2026

Type: article

Abstract: ABSTRACT Noonan syndrome (NS) is a RASopathy that can have hematological presentations, most commonly NS‐related myeloproliferative disorder (NS/MPD) and juvenile myelomonocytic leukemia. Other neonatal hematologic presentations remain poorly defined. We describe a neonate presenting with profound thrombocytopenia and hemolytic anemia, extensive evaluation excluding immune, infectious, and thrombotic microangiopathic etiologies. Subsequent trio whole‐genome sequencing identified a pathogenic heterozygous germline PTPN11 variant, confirming NS. The variant, NM_002834.5 c.794G>A (p.Arg265Gln), was inherited from an apparently asymptomatic parent. The patient had complete hematologic recovery over the first year of life. This case broadens the hematologic phenotype of NS and underscores the importance of considering RASopathies in neonatal cytopenias. Early molecular diagnosis informs management and surveillance in early childhood.

Source: eJHaem

DOI: 10.1002/jha2.70272

Authors: Ariel Gershon, Tanvi Anandampillai, Elaine Suk‐Ying Goh, Caroline Malcolmson, Yiming Wang

Institutions: Hospital for Sick Children, University of Toronto, Trillium Health Centre

Language: English

Topic: Protein Tyrosine Phosphatases

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,860