Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia, and X-linked congenital neutropenia collectively are designated WAS-related disorders. All are attributable to pathogenic variants of the WAS protein (WASp) and present a broad spectrum of hematopoietic cellular defects that chiefly involve platelets and lymphocytes. Pathogenic mutations in the WAS gene (located at Xp11.22-23) are implicated, affecting 12 exons.
Herein, we describe a neonate with congenital thrombocytopenia and platelet dysfunction due to a novel c.1500_1504dup (p.Asp502Gly) variant of the WAS gene. This mutation produces a frameshift, with substitution of aspartic acid for glycine at position 502 of the protein, and causes a downstream stop-loss codon. Clinically, the infant displayed severe thrombocytopenia and thrombasthenia, in the absence of other WAS-related traits (i.e., immune deficiency, eczema). Once a multigene panel analysis was complete, conditioning and then successful hematopoietic stem-cell transplantation took place at the age of 8 months. This case highlights the importance of genetic testing in instances where other diagnostics prove inconclusive.