3270
We have determined the parental origin of the retained allele in nine retinoblastoma tumours from eight unrelated non - familial cases by using RB1 - linked genetic markers .
 retinoblastoma tumours
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease 
Text: {0} 
Answer:
 retinoblastoma tumours