A 20-month-old female presented with a palpable abdominal mass. Imaging revealed bilateral renal masses and pulmonary nodules. The genetic evaluation identified a de novo 540kb X-chromosome deletion involving GPC3, PHF6, and HPRT1, and highly skewed X-inactivation (100:0). This clinical picture was suggestive of Wilms’ tumor in the setting of Simpson-Golabi-Behmel Syndrome.