MEDizzy - An 8-month-old infant boy presents with an enlarging

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Urinary System

An 8-month-old infant boy presents with an enlarging abdominal mass. Laboratory evaluation finds normal urinary levels of vanillylmandelic acid (VMA). The mass is removed surgically and microscopic sections reveal undifferentiated mesenchymal cells, immature tubules, and abortive glomerular formation. This tumor is most closely associated with abnormalities involving which one of the listed genes?

ExplanationMalignant tumors of the kidney in children are called nephroblastomas (Wilms tumor) and histologically reveal a combination of metanephric blastema, undifferentiated mesenchymal cells, and immature tubule or glomerular formation. Children present with an enlarging abdominal mass that, in contrast to adrenal neuroblastoma, is associated with normal urinary vanillylmandelic acid (VMA) levels. Deletions involving WT1, located on chromosome 11, are associated with the development of Wilms tumor (nephroblastoma). Several syndromes are associated with genetic deletions of WT1, that lead to an increased incidence of Wilms tumor. These include WAGR syndrome (characterized by aniridia, genital abnormalities, and mental retardation) and Denys-Drash syndrome (characterized by gonadal dysgenesis and renal failure). Deletions involving a second Wilms tumor gene (WT2) are associated with Beckwith-Wiedemann syndrome (characterized by hemihypertrophy, renal medullary cysts, and adrenal cytomegaly).