Retinoblastoma in Navajo Indian children.

Retinoblastoma occurs with an observed incidence of one in 18,000 live births, and 35% to 45% of cases are transmitted genetically in a dominant fashion. A retrospective analysis of Navajo Indian children during the past 15 years disclosed an incidence 21/2 to three times the expected. This observation raises the possibility that silent expression of the gene for retinoblastoma occurs more frequently among the Navajo population compared with the population at large.