Early-Onset Mucocutaneous Findings and Isolated Progressive Thrombocytopenia in a Child With a DKC1 A353V Variant.

Dyskeratosis congenita (DC) is a rare telomere biology disorder characterized by mucocutaneous abnormalities and progressive bone marrow failure. We report a 10-year-old boy with a hemizygous DKC1 c.1058C > T (p.Ala353Val) variant who presented with unusually early mucocutaneous findings, including oral leukoplakia at 2 years of age, followed by reticular skin hyperpigmentation, nail dystrophy, and later isolated, slowly progressive thrombocytopenia. Bone marrow examination revealed hypocellularity with reduced granulocytic and megakaryocytic precursors, supporting an inherited bone marrow failure syndrome, which was confirmed by genetic analysis. Hemoglobin and leukocyte counts remained stable during follow-up, and no transfusion requirement occurred. This case highlights that early mucocutaneous manifestations and isolated thrombocytopenia may represent initial features of DKC1-related DC, emphasizing the importance of early recognition and long-term multidisciplinary surveillance.