Autosomal Disorders

[bucket]

Can they be passed on to offspring??
I've seen pedigrees that clearly depict autosomal diseases, and then I get questions true/false questions such as "II-2 is heterozygous" in multiple choice!
How would you work this out?!

[bturville]

Diseases on autosomal chromosomes can still be passed on...

[bucket]

how do you work out whether or not a particular member of the next generation has the disease then?

[JL_91]

You need to look at the individual's parents and siblings. Work out their genotypes. It would be easier to explain if you had a sample question - do you have one on you?

[bucket]

ill scan one, sec.

[bturville]

Can they be passed on to offspring??
I've seen pedigrees that clearly depict autosomal diseases, and then I get questions true/false questions such as "II-2 is heterozygous" in multiple choice!
How would you work this out?!

You would only be able to tell if it was heterozygous if (for eg, it was an auto. rec. disorder) one parent had the disease, the other didn't, and the individual didn't.

[BA22]

This might seems a bit basic, but this is how i used to do it

First i would just look at the pedigree and kinda workout what type of inheritence it was






This image shows a dominant autosomal condition
The indications are:
 - Males and females affected equally, therefore sex-linked is not indicated
 - At least one person in every generation is affected 

So now we can workout genotypes based on the information we are given.

Genotypes: (N) disease (n) normal

I-1 Heterozygote (Nn) Has the disease but not all children are affected, therefore he must have one normal gene
I-2 Homozygote (nn) Does not display the disease and since the condition is dominant, must have both normal genes
II-1 Homozygote (nn) Not family, but has no affected children and does not display disease
II-2 Homozygote (nn) Does not display disease
  . . . .


You would keep on applying these principles until you worked out the genotype of the required individual. The most important thing you have to do is work out the type of inheritence

[bucket]

how about with autosomal recessive, how would you determine of one of the offspring was a carrier?

[BA22]

Autosomal recessive means that both parents contributed one allele leading to the disease

So if both parents are unaffected, then they most both be heterozygote carriers (Nn)

If one parent has the disease then they will be (nn), but the other parent must still be (Nn)

In short, if two parents produce any children that display an autosomal recessive condition, they they are both carriers

Determining the genotypes of offspring should be done mainly by considering the generations above and below. If the parents are both carriers, then it is impossible to distinguish (using simply the pedigree) whether the offspring is a carrier or not until they have offspring of their own

[bucket]

ah k thanks a lot