Specimen:

Blood

Collection Medium:

Minimum:

3 - 4 mL EDTA

Analytic Time:

12 weeks

Comments:

Label each tube with the patient's name and date sample was obtained.

Please print, complete and submit the Retinoblastoma (RB1) Forms 
from the University of Pennsylvania - Genetic Diagnostic Laboratory to 
the lab, with the specimen and the A-1a Miscellaneous Request.

In cases of patients with unilateral RB tumor and no family history, we 
recommend testing DNA isolated from the tumor before testing for 
mutation in RB1 gene in DNA isolated from blood.  Please advise the lab 
if tumor is available but not submitted with blood sample, so that we 
hold the blood until we have received and tested the tumor.  If we are 
not notified in advance that tumor will be coming, we will sequence the 
blood sample and if tumor is subsequently sent to be tested, there will 
be another sequencing charge.

Test
Limitations:

Retinoblastoma (RB) is a malignant tumor of the developing retina that 
occurs in children, usually before the age of five years.  
Retinoblastoma may be unilateral or bilateral. About 60% of patients 
have unilateral RB with a mean age of diagnosis of 24 months; about 40%
have bilateral RB with a mean age of diagnosis of 15 months. Mutations 
in the RB gene (chromosomal location 13q14) predispose individuals to 
the disease and an increased risk of developing other RB-related 
(non-ocular) tumors.

If the patient has a mutation in the coding sequence of the RB1 gene, 
the testing will detect the mutation >99% of the time. Mutations in 
non-coding sequences, insertions, deletions or rearrangements will not 
be detected by sequencing.  The probability that an RB1 gene mutation 
will be detected in an index case depends upon whether the tumor is 
unilateral or bilateral and whether the family history is positive or 
negative.

Methodology:

Direct mutation analysis by full sequencing

CPT Code:

83891, 83894(x21), 83898(x24), 83904(x21), 83912