If the disease is AR and homozygous gene then you should use q2 but heterozygous gene use 2pq. Chances of inheriting a trait: Disease 25%, Carrier 67%.If the question asks about the carrier of an autosomal recessive disease, do we use 2pq or pq?
e.g. if disease X (which we know is AR) has an incidence of 1/625, what is the carrier? And why?
Autosomal Recessive DiseasesSo what is the carrier? is pq or 2pq? Do you divide by 2 to get the carrier?
No, this is wrong.Many thanks for your help, guys, But that last point confused me:
So for example, if incidence of an AR disease is 1/100. then:
Carrier = 2pq = 2 x 1 x 1/100 = 1/50
Is that right?
In AD diseases, frequency of affected persons is simply equal to carrier frequency, since all carriers are also affected. Thus, 2pq or 2q (since p is approx. = 1) is used for both frequencies of carriers and affected persons.Also, why in AD do we consider affected = q`2? isn't it q`2 + 2pq?
No problem. Please refer to my post #5 above, and just memorize it as-is! It helped me a lot in the exam and in Qbanks. Just don't forget to get the root when given an incidence/prevalence of an AR disease or an XR disease in females (since both are = q^2) if the question is asking about the carrier prevalence (2q).Well that clears things, thanks a lot