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+--- Thread: genetics question - (/showthread.php?tid=20112)
genetics question - - ArchivalUser - 08-19-2004
sebastian
dude comes in that has had no retinoblastomas (Rb), but has produced 2 kids w/ multiple Rbs. His dad also had 2 Rbs and one of his brothers has 3 Rbs. Which of the following is the most likely explanation for the abscence of the retinoblastoma in this individual?
-pleiotropy
-
0 - ArchivalUser - 08-19-2004
mash
incomplete penetrance
0 - ArchivalUser - 08-19-2004
sebastian
sorry, accidently clicked submit....
remaining 4 choices:
-highly variable expression of the disorder
-incomplete penetrance
-multiple new mutations in other family members
-a new mutation in the unaffected individual, which has corrected the disease-causing mutation
0 - ArchivalUser - 08-19-2004
sebastian
damn Mash!!!!!
0 - ArchivalUser - 08-19-2004
sebastian
one question though, Mash....if you need 2 mutations for expression of the tumor, isnt it more of a case of the guy not having suffered that 2nd mutation (while his family members have)?!? I thought imcomplete penetrance was more of having ALL the mutations necessary for the phenotypic alteration....but simply not expression it. You get what i mean?!?
0 - ArchivalUser - 08-19-2004
sebastian
as defined in 1st aid...he doesn't possess the required "2" mutations needed for altered expression, correct?!?
0 - ArchivalUser - 08-19-2004
mash
u r right but retinoblastoma is AD and as such just one mutant allele is reqd ...bcoz it is a tm suppressor gene, 2nd hit is reqd to express the ds.
incomplete penetrance is when the person inherits the mutant allele and he shud express it but he doesn't
ideally he shud ve had retinoblastoma bcoz he transmitted the mutant allele to his sons(rb being AD)
0 - ArchivalUser - 08-19-2004
sebastian
Gotcha.....Thanks Mash for your help!!