roopashri
Forum Elite
Topics: 16
Posts: 190
|
A man is affected with tyrosinase-negative oculocutaneous albinism (autosomal recessive). Based on this information alone, what is the probability that his grandson and his great-granddaughter are both heterozygous carriers of the albinism gene?
|
| sturge_weber
Forum Guru
Topics: 77
Posts: 1,042
|
one fourth, and one eighth chances
|
| drk1980
Forum Guru
Topics: 147
Posts: 1,038
|
sturge_weber, do u hv literature u can share for the confirmation of ur answer?
thanks
|
| roopashri
Forum Elite
Topics: 16
Posts: 190
|
sturge_weber, i dont have answer for this qn. I too think the same. it would be helpful if u can explain
|
| sturge_weber
Forum Guru
Topics: 77
Posts: 1,042
|
well there re too types of oculocutaneous albinism, tyrosinase negative and tyrosinase positive, well u just need to know that if someone has one gene for the tyrosinase negative and the other for the tyrosinase positiv, he will be a carrier fr both types , but will not manifest the disease
this was n0ot related to the q, in this q they re asking about the coeffecient of relationship, and u need to know only this much for it, real brothers and sisters share half of their genes, mother and child also half of their genes, uncle and neice and grandparents and grandchildren share 1/4 of their genes, and first cousins share 1/8 of their genes.. and so on
most of the answers relating to the coeffecient of relationship can be derived fronm only this relationship...
|
| roopashri
Forum Elite
Topics: 16
Posts: 190
|
thanks !
|
| roopashri
Forum Elite
Topics: 16
Posts: 190
|
this is how i did.... man to son - 1/2, son to grandson 1/2 so probability of grand son is 1/4
man to daughter is 1/2, daughter to grand daughter is 1/2, grand daughter to great grand daughter is 1/2 , so the probabilty of great grand daughter being carrier is 1/8
but here the q is about co efficient of relationship i.e the degree of heterozygosity shared between the grandson and great grand daughter , now i have a doubt... is co-eff of relationship same as the probability??
pls help me out
|
| elisamik
Forum Senior
Topics: 2
Posts: 39
|
some modifications to the answer:
prob to pass the gene to the grandson: 1/4x1/2=1/8. you take into account that the qt is asking about the 'grandSon', ie 1/2 prob of being a male.
same with the greatgranddaughter: 1/8x1/2x1/2=1/32
if qt is asking about combined probab: 1/8x1/32=1/256
anybody agrees?
|
|
| |
| | | | | | | | |
