Acute leukemia in a patient with 15q overgrowth syndrome.

Overgrowth syndromes are rare genetic conditions which present as global or segmental hyperplasia and are sometimes associated with increased risk of malignancy. Trisomy of the terminal portion of 15q which includes the IGFR1 gene, produces a rare overgrowth phenotype that has been termed 15q overgrowth syndrome (15q OGS). Upregulation of IGF1R has long been implicated in oncogenesis of multiple cancer types, including acute leukemias, and has been shown to render cells more susceptible to other transforming events. To date, too few cases of 15q OGS have been reported to identify any cancer predisposition. We present a case of a 34-year-old female with intellectual disability, macrocephaly, and subtle dysmorphic features who was diagnosed with mixed phenotype acute leukemia (lymphoid and myeloid). Prior to initiation of therapy she was referred to medical genetics for further evaluation and was identified as having a chromosomal translocation resulting in a partial trisomy of chromosome 15q, consistent with 15q OGS. A review of the literature for cases of malignancy in individuals with increased copy number of 15q revealed only one other reported patient. Given the small number of reported individuals, we cannot rule out an increased risk of cancer associated with this chromosomal overgrowth syndrome. Although concerns have been raised regarding treatment feasibility in the setting of chromosomal disorders, the reported patient underwent successful treatment with allogeneic hematopoietic stem-cell transplant.