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Rhabdoid tumors in a shared parental environment

To the Editor: Rhabdoid tumor is a highly aggressive tumor of infancy most commonly found in the kidneys and CNS [1,2]. The primary known etiologic factor is mutation of hSNF5/INI1 at chromosome 22q11.2 encoding a protein in the SWI/SNF ATP-dependent chromatin-remodeling complex [3–6]. It is unclear as to how many germ-line mutations of hSNF5/INI1 are de novo versus inherited and we read with interest the recent article by Janson et al. [7] which describes the inherited predisposition to develop atypical teratoid/ rhabdoid tumor by means of hSNF5/INI1 mutation transmitted via an asymptomatic carrier. We recently treated two unrelated children with rhabdoid tumor from the same geographic area and who each had a parent that worked at the same job site, a computer technology corporation housed in a building previously built and utilized by the government. A third case had also been noted 2 years previously with a parent from the same employment site. The first case involved a 4-month-old Caucasian female who developed an atypical teratoid/rhabdoid tumor of the posterior fossa. She was treated with two surgical resections and chemotherapy and is currently alive at 4 years from diagnosis. Upon obtaining an IRB-approved informed consent, genetic analysis was performed which demonstrated a germ-line mutation of the SNF5/INI1 gene at codon 154 (462delC) in the patient. The father worked at the job site mentioned above prior to conception and during the child’s gestation and infancy. Three years after diagnosis of the first case, a 4-month-old Asian–American male presented with a stage 1 rhabdoid tumor of the kidney. Three months after diagnosis he developed a mandibular mass encroaching upon the carotid canal, optic canal, and sphenoid bone. The patient died 1 month later. It was not known if the mandibular mass represented a metastasis or a new primary tumor. After obtaining IRB-approved informed consent, genetic analysis was performed which did not reveal a germ-line mutation of the hSNF5/INI1 gene in either the patient or the parents. The mother was employed at the same site as the father of the previous case prior to conception and during the child’s gestation and infancy. A third case of rhabdoid tumor of the kidney occurred in a child of another worker at the same facility. The diagnosis was made approximately 2 years prior to that of case 1. However, the family of this patient was not contacted and further genetic analysis and questioning was not performed. Rhabdoid tumors are extremely rare in the general population with rhabdoid tumor of the kidney representing only 1.6% of childhood renal tumors [8] corresponding to a frequency of approximately 1 in 600,000 children. The rarity and the difficulty in determining common environmental exposures amongst widely dispersed cases present a challenge to further studies. Our cluster of cases, however, suggest that environmental factors may also be involved in the development of rhabdoid tumors, although we are unable to identify specific factors. Further research on the role of environment in the etiology of rhabdoid tumors needs to be explored.