question about genetics

Shorty11, BSN, RN · Oct 26, 2012

As per the Terms of Service of allnurses, we aren't supposed to answer the question outright for you. But we defiantly are willing to help if you provide what you have so far...

Genetics Basics Simplified:

Pedigrees are listed typically as males being squares and females being circles.

Mating denoted by a line horizontally connecting a male and female. A line connecting to squares/circles below (vertically) denoting offspring.

Allele- one form of a particular gene (genetic locus) that a person has.

Humans are diploid organisms meaning that they have (typically) two alleles (or copies) of each gene. One from mom and one from dad. These two alleles together form the genotype. The genotype is the set of two alleles that a human has.

If the two alleles for a gene are the same, the individual is homozygous for that trait.

If the two alleles for a gene are different, the individual is heterozygous for that trait.

The phenotype is the observable expression of the genotype.

Basically, Alleles are dominant, recessive, or sex-linked.

I use an "A" to denote a dominate allele and an "a" to denote a recessive allele (or whatever letters you want, just make the dominant capital and the recessive lower-case.)

A person has two alleles (one from each parent), either an AA, Aa, or aa.

A person that is "AA" is homozygous dominant (genotype) and will express the dominant trait as the phenotype.

A person that is "Aa" is heterozygous dominant (genotype) and will express the dominant trait as the phenotype.

A person that is "aa" is homozygous recessive (genotype) and will express the recessive trait as the phenotype.

Use a Punnet Square if you have problems. I can't really demonstrate that here but there are great help websites out there...

Sex-linked traits:

Sex-linked traits are carried on the X-chromosome. (Females have two X's, Males has an X and a Y.)

Since females have two X chromosomes, if the trait is sex-linked, the female has two copies of the chromosome so dominance can occur, resulting in a symptomless CARRIER.

Males only have one X chromosome, so they are either affected or unaffected. There are NO CARRIER males for sex-linked traits.

If the condition is not shown in any of the first generation offspring, but reappears in the second, it must be recessive.

This is obviously not everything (Just a simple Intro.)... Genetics is complicated!... but maybe that cleared a few things up..

If you specifically ask what question you have versus just analyzing the entire pedigree for you, more help can probably be offered.

Tell me what you have so far and I'll try to help!

Esme12, ASN, BSN, RN · Oct 26, 2012

It isn't really a "Terms of Service" issue really. It's an ethical thing. allnurses and I promote the profession and making those who want to enter the best nurse they can be....me doing their work won't accomplish that goal.

Genetics??? Soooooo NOT my forte......All yours shorty.....

Shorty11, BSN, RN · Oct 26, 2012

Esme is right (as usual : ) ) I was just trying to think of a reason to not just flat out answer the problem. Lol. Analyzing the pedigree for you really won't help you in the long run..

All Nurses is an amazing support system, but not a homework service. If you provide what you have so far, we would be happy to help though! What in particular are you struggling with?

Esme12, ASN, BSN, RN · Oct 26, 2012

GO for it shorty..... :yes: . Answer away...outta my league.

ps......I just call it as I seem em politely. :)

Shorty11, BSN, RN · Oct 26, 2012

Trying to pay it forward when possible...

(Can't tell you enough have you have helped me with care plans and nursing dx just from reading your responses, Esme!)

Esme12, ASN, BSN, RN · Oct 26, 2012

...you're welcome.((HUGS))