I need help on this biology problem...relating to Dwarfism?

Question

How do you do this problem? THe answer I got was 100%..but i think that is wrong....What are the paretns and gametes?

Achondroplastic dwarfism is duw to a lethal dominant trait. Two achondroplastic dwarfs marry each other and decide to have hcildren. What is the probabililty of a cenceoption resulting in a normal child?

Answer 1

You have to consider that it is a lethal dominant trait, so the parents both MUST be heterozygous for the trait.

Then just do a punnet square with DdxDd.

The trick is that DD is, again, lethal. 1/4 of the time you get DD which is lethal. 2/4 you get Dd, and 1/4 you get dd. Taking the lethality into account, 2/3 of the time you get dwarfism, and 1/3 of the time the child is unaffected.

Answer 2

If the parents are homozygous (both DD)for the dwarfism trait then there is a 100% probability the children will exhibit dwarfism and will be homozygous for the trait.

If the parents are both heterozygous (Dd) for the dwarfism trait then there is a 75% probability the children will inherit (do your punnit square) with a 33% chance of being homozygous for the trait.

If one parent is homozygous9DD) and one parent is heterozygous (Dd) there is a 100% probability the children will exhibit dwarfism but the CHILDREN will be either homozygous or heterozygous (50% probability).

Answer 3

Homozygous FGFR3 mutations usually result in death from achondroplasia in utero or during infancy. Therefore, nobody who is homozygous for achondroplasia can survive to reproduce. The parents would HAVE to both be heterozygous for the FGFR3 mutation, meaning the genotpes will be 1:2:1, (meaning 3:1 phenotypic ratio of affected vs unaffected) and there is a 1/4 chance they will have a normal child.

Answer 4

please. next time, run your question through spell check. i kind of had problems in fully understanding your question. if i read your question correctly & assuming each dwarf were reproductive possible, chances of having a child reflective of both parents are 100%. first, however, and to be accurate, check the parents of the parents, etc. go back as far as you can with both sides. dna is not a simple case of shooting craps & a fairly accurate prediction is possible but only if all info (as possible) is present. when not, then immediate dna of first & second generations would be needed. see, the key word in your question is "dominent". if it was recessive, well then... but dominent speaks for itself. nature, however, and as cruel as it sounds, takes care of its mistakes by shortening the lifespan of such birth 'problems' or will make it so that furthering the 'mistake' can not be by making one or both parents sterile. now, to clarify my answer, you ask about conceiving a 'normal' child to such parents, the probability is 100% of not happening. both parents are of this dwarfism ? both carry this dominent dwarfism gene? normal child? only if they adopt but realistic chances of a normal child is , as stated, 100% NOT!

Answer 5

G'day Hellokid,

Thank you for your question.

A lethal dominant trait is one that when expressed means that the child will die of it. There is a high chance that the child of achrondoplastic dwarfs will die shortly after birth. However, you can now get tests done.

I have attached sources for your reference.

Regards

Answer 6

If it is due to a dominant trait, then I would assume it would depend on their genes. They could both carry two dominant traits (DD, DD) a dominant and recessive (Dd, Dd) or one of each (DD, Dd). Only the (Dd, Dd) could possibly result in not passing dwarfism (25% chance)

Answer 7

About 50%, you wouldhave to consider ancestral DNA. You would have to look at the grandparents DNA took make any kind of decision.

Answer 8

thats easy....... u have 2 dwarf people who make a child....... 1 child..... the child has a 2 out of 3 chance of becoming a dwarf.....